Make the round participants sign the vtxo tree (#271)

* [proto] add APIs to send and receive musig2 signing data

* [common] add serialization functions for nonces and signatures

* [application] implements tree signing

* fix: remove old debug logs

* [proto] cleaning

* [common] fix musig2.go

* [application] fixes and logs

* [interface] fix: stop forwarding 2 times the events

* [client] add musig2 support + sign the tree when joining a round

* [interface] add new APIs into permissions.go

* [application][proto] rework PingResponse (return all events type)

* [common] split SetKeys into 2 distinct methods

* [client] fixes according to musig2.go changes

* [sdk] support tree signing + new PingResponse

* [sdk] fixes

* [application] revert event channel type

* [application] use domain.RoundEvent as lastEvent type

* [application] remove IsCovenantLess

* comments

* [application] revert roundAborted changes

* [interface] remove bitcointree dependencie

api-spec/openapi/swagger/ark/v1/service.swagger.json

@@ -261,6 +261,70 @@
         ]
       }
     },
+    "/v1/payment/tree/nonces": {
+      "post": {
+        "operationId": "ArkService_SendTreeNonces",
+        "responses": {
+          "200": {
+            "description": "A successful response.",
+            "schema": {
+              "$ref": "#/definitions/v1SendTreeNoncesResponse"
+            }
+          },
+          "default": {
+            "description": "An unexpected error response.",
+            "schema": {
+              "$ref": "#/definitions/rpcStatus"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "name": "body",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/v1SendTreeNoncesRequest"
+            }
+          }
+        ],
+        "tags": [
+          "ArkService"
+        ]
+      }
+    },
+    "/v1/payment/tree/signatures": {
+      "post": {
+        "operationId": "ArkService_SendTreeSignatures",
+        "responses": {
+          "200": {
+            "description": "A successful response.",
+            "schema": {
+              "$ref": "#/definitions/v1SendTreeSignaturesResponse"
+            }
+          },
+          "default": {
+            "description": "An unexpected error response.",
+            "schema": {
+              "$ref": "#/definitions/rpcStatus"
+            }
+          }
+        },
+        "parameters": [
+          {
+            "name": "body",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/v1SendTreeSignaturesRequest"
+            }
+          }
+        ],
+        "tags": [
+          "ArkService"
+        ]
+      }
+    },
     "/v1/ping/{paymentId}": {
       "get": {
         "operationId": "ArkService_Ping",
@@ -323,7 +387,6 @@
     },
     "/v1/round/{txid}": {
       "get": {
-        "summary": "TODO BTC: signTree rpc",
         "operationId": "ArkService_GetRound",
         "responses": {
           "200": {
@@ -502,14 +565,19 @@
       "type": "object",
       "properties": {
         "roundFinalization": {
-          "$ref": "#/definitions/v1RoundFinalizationEvent",
+          "$ref": "#/definitions/v1RoundFinalizationEvent"
-          "title": "TODO: BTC add \"signTree\" event"
         },
         "roundFinalized": {
           "$ref": "#/definitions/v1RoundFinalizedEvent"
         },
         "roundFailed": {
           "$ref": "#/definitions/v1RoundFailed"
+        },
+        "roundSigning": {
+          "$ref": "#/definitions/v1RoundSigningEvent"
+        },
+        "roundSigningNoncesGenerated": {
+          "$ref": "#/definitions/v1RoundSigningNoncesGeneratedEvent"
         }
       }
     },
@@ -649,14 +717,20 @@
     "v1PingResponse": {
       "type": "object",
       "properties": {
-        "forfeitTxs": {
+        "roundFinalization": {
-          "type": "array",
-          "items": {
-            "type": "string"
-          }
-        },
-        "event": {
           "$ref": "#/definitions/v1RoundFinalizationEvent"
+        },
+        "roundFinalized": {
+          "$ref": "#/definitions/v1RoundFinalizedEvent"
+        },
+        "roundFailed": {
+          "$ref": "#/definitions/v1RoundFailed"
+        },
+        "roundSigning": {
+          "$ref": "#/definitions/v1RoundSigningEvent"
+        },
+        "roundSigningNoncesGenerated": {
+          "$ref": "#/definitions/v1RoundSigningNoncesGeneratedEvent"
         }
       }
     },
@@ -669,6 +743,9 @@
             "type": "object",
             "$ref": "#/definitions/v1Input"
           }
+        },
+        "ephemeralPubkey": {
+          "type": "string"
         }
       }
     },
@@ -766,6 +843,34 @@
         }
       }
     },
+    "v1RoundSigningEvent": {
+      "type": "object",
+      "properties": {
+        "id": {
+          "type": "string"
+        },
+        "cosignersPubkeys": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "unsignedTree": {
+          "$ref": "#/definitions/v1Tree"
+        }
+      }
+    },
+    "v1RoundSigningNoncesGeneratedEvent": {
+      "type": "object",
+      "properties": {
+        "id": {
+          "type": "string"
+        },
+        "treeNonces": {
+          "type": "string"
+        }
+      }
+    },
     "v1RoundStage": {
       "type": "string",
       "enum": [
@@ -777,6 +882,40 @@
       ],
       "default": "ROUND_STAGE_UNSPECIFIED"
     },
+    "v1SendTreeNoncesRequest": {
+      "type": "object",
+      "properties": {
+        "roundId": {
+          "type": "string"
+        },
+        "publicKey": {
+          "type": "string"
+        },
+        "treeNonces": {
+          "type": "string"
+        }
+      }
+    },
+    "v1SendTreeNoncesResponse": {
+      "type": "object"
+    },
+    "v1SendTreeSignaturesRequest": {
+      "type": "object",
+      "properties": {
+        "roundId": {
+          "type": "string"
+        },
+        "publicKey": {
+          "type": "string"
+        },
+        "treeSignatures": {
+          "type": "string"
+        }
+      }
+    },
+    "v1SendTreeSignaturesResponse": {
+      "type": "object"
+    },
     "v1Tree": {
       "type": "object",
       "properties": {

api-spec/protobuf/ark/v1/service.proto

@@ -17,13 +17,24 @@ service ArkService {
       body: "*"
     };
   };
+  rpc SendTreeNonces(SendTreeNoncesRequest) returns (SendTreeNoncesResponse) {
+    option (google.api.http) = {
+      post: "/v1/payment/tree/nonces"
+      body: "*"
+    };
+  }
+  rpc SendTreeSignatures(SendTreeSignaturesRequest) returns (SendTreeSignaturesResponse) {
+    option (google.api.http) = {
+      post: "/v1/payment/tree/signatures"
+      body: "*"
+    };
+  }
   rpc FinalizePayment(FinalizePaymentRequest) returns (FinalizePaymentResponse) {
     option (google.api.http) = {
       post: "/v1/payment/finalize"
       body: "*"
     };
   };
-  // TODO BTC: signTree rpc 
   rpc GetRound(GetRoundRequest) returns (GetRoundResponse) {
     option (google.api.http) = {
       get: "/v1/round/{txid}"
@@ -91,6 +102,7 @@ message CompletePaymentResponse {}
 
 message RegisterPaymentRequest {
   repeated Input inputs = 1;
+  optional string ephemeral_pubkey = 2;
 }
 message RegisterPaymentResponse {
   // Mocks wabisabi's credentials.
@@ -128,10 +140,11 @@ message GetRoundByIdResponse {
 message GetEventStreamRequest {}
 message GetEventStreamResponse {
   oneof event {
-    // TODO: BTC add "signTree" event
     RoundFinalizationEvent round_finalization = 1;
     RoundFinalizedEvent round_finalized = 2;
     RoundFailed round_failed = 3;
+    RoundSigningEvent round_signing = 4;
+    RoundSigningNoncesGeneratedEvent round_signing_nonces_generated = 5; 
   }
 }
 
@@ -139,8 +152,13 @@ message PingRequest {
   string payment_id = 1;
 }
 message PingResponse {
-  repeated string forfeit_txs = 1;
+  oneof event {
-  RoundFinalizationEvent event = 2;
+    RoundFinalizationEvent round_finalization = 1;
+    RoundFinalizedEvent round_finalized = 2;
+    RoundFailed round_failed = 3;
+    RoundSigningEvent round_signing = 4;
+    RoundSigningNoncesGeneratedEvent round_signing_nonces_generated = 5; 
+  }
 }
 
 message ListVtxosRequest {
@@ -189,6 +207,17 @@ message RoundFailed {
   string reason = 2;
 }
 
+message RoundSigningEvent {
+  string id = 1;
+  repeated string cosigners_pubkeys = 2;
+  Tree unsigned_tree = 3;
+}
+
+message RoundSigningNoncesGeneratedEvent {
+  string id = 1;
+  string tree_nonces = 2;
+}
+
 // TYPES
 
 enum RoundStage {
@@ -252,3 +281,19 @@ message PendingPayment {
   string redeem_tx = 1;
   repeated string unconditional_forfeit_txs =2;
 }
+
+message SendTreeNoncesRequest {
+  string round_id = 1;
+  string public_key = 2;
+  string tree_nonces = 3;
+}
+
+message SendTreeNoncesResponse {}
+
+message SendTreeSignaturesRequest {
+  string round_id = 1;
+  string public_key = 2;
+  string tree_signatures = 3;
+}
+
+message SendTreeSignaturesResponse {}

api-spec/protobuf/gen/ark/v1/service.pb.gw.go

@@ -83,6 +83,58 @@ func local_request_ArkService_ClaimPayment_0(ctx context.Context, marshaler runt
 
 }
 
+func request_ArkService_SendTreeNonces_0(ctx context.Context, marshaler runtime.Marshaler, client ArkServiceClient, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq SendTreeNoncesRequest
+	var metadata runtime.ServerMetadata
+
+	if err := marshaler.NewDecoder(req.Body).Decode(&protoReq); err != nil && err != io.EOF {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+
+	msg, err := client.SendTreeNonces(ctx, &protoReq, grpc.Header(&metadata.HeaderMD), grpc.Trailer(&metadata.TrailerMD))
+	return msg, metadata, err
+
+}
+
+func local_request_ArkService_SendTreeNonces_0(ctx context.Context, marshaler runtime.Marshaler, server ArkServiceServer, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq SendTreeNoncesRequest
+	var metadata runtime.ServerMetadata
+
+	if err := marshaler.NewDecoder(req.Body).Decode(&protoReq); err != nil && err != io.EOF {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+
+	msg, err := server.SendTreeNonces(ctx, &protoReq)
+	return msg, metadata, err
+
+}
+
+func request_ArkService_SendTreeSignatures_0(ctx context.Context, marshaler runtime.Marshaler, client ArkServiceClient, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq SendTreeSignaturesRequest
+	var metadata runtime.ServerMetadata
+
+	if err := marshaler.NewDecoder(req.Body).Decode(&protoReq); err != nil && err != io.EOF {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+
+	msg, err := client.SendTreeSignatures(ctx, &protoReq, grpc.Header(&metadata.HeaderMD), grpc.Trailer(&metadata.TrailerMD))
+	return msg, metadata, err
+
+}
+
+func local_request_ArkService_SendTreeSignatures_0(ctx context.Context, marshaler runtime.Marshaler, server ArkServiceServer, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq SendTreeSignaturesRequest
+	var metadata runtime.ServerMetadata
+
+	if err := marshaler.NewDecoder(req.Body).Decode(&protoReq); err != nil && err != io.EOF {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+
+	msg, err := server.SendTreeSignatures(ctx, &protoReq)
+	return msg, metadata, err
+
+}
+
 func request_ArkService_FinalizePayment_0(ctx context.Context, marshaler runtime.Marshaler, client ArkServiceClient, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
 	var protoReq FinalizePaymentRequest
 	var metadata runtime.ServerMetadata
@@ -486,6 +538,56 @@ func RegisterArkServiceHandlerServer(ctx context.Context, mux *runtime.ServeMux,
 
 	})
 
+	mux.Handle("POST", pattern_ArkService_SendTreeNonces_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(req.Context())
+		defer cancel()
+		var stream runtime.ServerTransportStream
+		ctx = grpc.NewContextWithServerTransportStream(ctx, &stream)
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		var err error
+		var annotatedContext context.Context
+		annotatedContext, err = runtime.AnnotateIncomingContext(ctx, mux, req, "/ark.v1.ArkService/SendTreeNonces", runtime.WithHTTPPathPattern("/v1/payment/tree/nonces"))
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := local_request_ArkService_SendTreeNonces_0(annotatedContext, inboundMarshaler, server, req, pathParams)
+		md.HeaderMD, md.TrailerMD = metadata.Join(md.HeaderMD, stream.Header()), metadata.Join(md.TrailerMD, stream.Trailer())
+		annotatedContext = runtime.NewServerMetadataContext(annotatedContext, md)
+		if err != nil {
+			runtime.HTTPError(annotatedContext, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_ArkService_SendTreeNonces_0(annotatedContext, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
+	mux.Handle("POST", pattern_ArkService_SendTreeSignatures_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(req.Context())
+		defer cancel()
+		var stream runtime.ServerTransportStream
+		ctx = grpc.NewContextWithServerTransportStream(ctx, &stream)
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		var err error
+		var annotatedContext context.Context
+		annotatedContext, err = runtime.AnnotateIncomingContext(ctx, mux, req, "/ark.v1.ArkService/SendTreeSignatures", runtime.WithHTTPPathPattern("/v1/payment/tree/signatures"))
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := local_request_ArkService_SendTreeSignatures_0(annotatedContext, inboundMarshaler, server, req, pathParams)
+		md.HeaderMD, md.TrailerMD = metadata.Join(md.HeaderMD, stream.Header()), metadata.Join(md.TrailerMD, stream.Trailer())
+		annotatedContext = runtime.NewServerMetadataContext(annotatedContext, md)
+		if err != nil {
+			runtime.HTTPError(annotatedContext, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_ArkService_SendTreeSignatures_0(annotatedContext, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
 	mux.Handle("POST", pattern_ArkService_FinalizePayment_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
 		ctx, cancel := context.WithCancel(req.Context())
 		defer cancel()
@@ -803,6 +905,50 @@ func RegisterArkServiceHandlerClient(ctx context.Context, mux *runtime.ServeMux,
 
 	})
 
+	mux.Handle("POST", pattern_ArkService_SendTreeNonces_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(req.Context())
+		defer cancel()
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		var err error
+		var annotatedContext context.Context
+		annotatedContext, err = runtime.AnnotateContext(ctx, mux, req, "/ark.v1.ArkService/SendTreeNonces", runtime.WithHTTPPathPattern("/v1/payment/tree/nonces"))
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := request_ArkService_SendTreeNonces_0(annotatedContext, inboundMarshaler, client, req, pathParams)
+		annotatedContext = runtime.NewServerMetadataContext(annotatedContext, md)
+		if err != nil {
+			runtime.HTTPError(annotatedContext, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_ArkService_SendTreeNonces_0(annotatedContext, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
+	mux.Handle("POST", pattern_ArkService_SendTreeSignatures_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(req.Context())
+		defer cancel()
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		var err error
+		var annotatedContext context.Context
+		annotatedContext, err = runtime.AnnotateContext(ctx, mux, req, "/ark.v1.ArkService/SendTreeSignatures", runtime.WithHTTPPathPattern("/v1/payment/tree/signatures"))
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := request_ArkService_SendTreeSignatures_0(annotatedContext, inboundMarshaler, client, req, pathParams)
+		annotatedContext = runtime.NewServerMetadataContext(annotatedContext, md)
+		if err != nil {
+			runtime.HTTPError(annotatedContext, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_ArkService_SendTreeSignatures_0(annotatedContext, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
 	mux.Handle("POST", pattern_ArkService_FinalizePayment_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
 		ctx, cancel := context.WithCancel(req.Context())
 		defer cancel()
@@ -1031,6 +1177,10 @@ var (
 
 	pattern_ArkService_ClaimPayment_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2}, []string{"v1", "payment", "claim"}, ""))
 
+	pattern_ArkService_SendTreeNonces_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2, 2, 3}, []string{"v1", "payment", "tree", "nonces"}, ""))
+
+	pattern_ArkService_SendTreeSignatures_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2, 2, 3}, []string{"v1", "payment", "tree", "signatures"}, ""))
+
 	pattern_ArkService_FinalizePayment_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2}, []string{"v1", "payment", "finalize"}, ""))
 
 	pattern_ArkService_GetRound_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 1, 0, 4, 1, 5, 2}, []string{"v1", "round", "txid"}, ""))
@@ -1057,6 +1207,10 @@ var (
 
 	forward_ArkService_ClaimPayment_0 = runtime.ForwardResponseMessage
 
+	forward_ArkService_SendTreeNonces_0 = runtime.ForwardResponseMessage
+
+	forward_ArkService_SendTreeSignatures_0 = runtime.ForwardResponseMessage
+
 	forward_ArkService_FinalizePayment_0 = runtime.ForwardResponseMessage
 
 	forward_ArkService_GetRound_0 = runtime.ForwardResponseMessage

api-spec/protobuf/gen/ark/v1/service_grpc.pb.go

@@ -20,8 +20,9 @@ const _ = grpc.SupportPackageIsVersion7
 type ArkServiceClient interface {
 	RegisterPayment(ctx context.Context, in *RegisterPaymentRequest, opts ...grpc.CallOption) (*RegisterPaymentResponse, error)
 	ClaimPayment(ctx context.Context, in *ClaimPaymentRequest, opts ...grpc.CallOption) (*ClaimPaymentResponse, error)
+	SendTreeNonces(ctx context.Context, in *SendTreeNoncesRequest, opts ...grpc.CallOption) (*SendTreeNoncesResponse, error)
+	SendTreeSignatures(ctx context.Context, in *SendTreeSignaturesRequest, opts ...grpc.CallOption) (*SendTreeSignaturesResponse, error)
 	FinalizePayment(ctx context.Context, in *FinalizePaymentRequest, opts ...grpc.CallOption) (*FinalizePaymentResponse, error)
-	// TODO BTC: signTree rpc
 	GetRound(ctx context.Context, in *GetRoundRequest, opts ...grpc.CallOption) (*GetRoundResponse, error)
 	GetRoundById(ctx context.Context, in *GetRoundByIdRequest, opts ...grpc.CallOption) (*GetRoundByIdResponse, error)
 	GetEventStream(ctx context.Context, in *GetEventStreamRequest, opts ...grpc.CallOption) (ArkService_GetEventStreamClient, error)
@@ -59,6 +60,24 @@ func (c *arkServiceClient) ClaimPayment(ctx context.Context, in *ClaimPaymentReq
 	return out, nil
 }
 
+func (c *arkServiceClient) SendTreeNonces(ctx context.Context, in *SendTreeNoncesRequest, opts ...grpc.CallOption) (*SendTreeNoncesResponse, error) {
+	out := new(SendTreeNoncesResponse)
+	err := c.cc.Invoke(ctx, "/ark.v1.ArkService/SendTreeNonces", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *arkServiceClient) SendTreeSignatures(ctx context.Context, in *SendTreeSignaturesRequest, opts ...grpc.CallOption) (*SendTreeSignaturesResponse, error) {
+	out := new(SendTreeSignaturesResponse)
+	err := c.cc.Invoke(ctx, "/ark.v1.ArkService/SendTreeSignatures", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 func (c *arkServiceClient) FinalizePayment(ctx context.Context, in *FinalizePaymentRequest, opts ...grpc.CallOption) (*FinalizePaymentResponse, error) {
 	out := new(FinalizePaymentResponse)
 	err := c.cc.Invoke(ctx, "/ark.v1.ArkService/FinalizePayment", in, out, opts...)
@@ -178,8 +197,9 @@ func (c *arkServiceClient) CompletePayment(ctx context.Context, in *CompletePaym
 type ArkServiceServer interface {
 	RegisterPayment(context.Context, *RegisterPaymentRequest) (*RegisterPaymentResponse, error)
 	ClaimPayment(context.Context, *ClaimPaymentRequest) (*ClaimPaymentResponse, error)
+	SendTreeNonces(context.Context, *SendTreeNoncesRequest) (*SendTreeNoncesResponse, error)
+	SendTreeSignatures(context.Context, *SendTreeSignaturesRequest) (*SendTreeSignaturesResponse, error)
 	FinalizePayment(context.Context, *FinalizePaymentRequest) (*FinalizePaymentResponse, error)
-	// TODO BTC: signTree rpc
 	GetRound(context.Context, *GetRoundRequest) (*GetRoundResponse, error)
 	GetRoundById(context.Context, *GetRoundByIdRequest) (*GetRoundByIdResponse, error)
 	GetEventStream(*GetEventStreamRequest, ArkService_GetEventStreamServer) error
@@ -201,6 +221,12 @@ func (UnimplementedArkServiceServer) RegisterPayment(context.Context, *RegisterP
 func (UnimplementedArkServiceServer) ClaimPayment(context.Context, *ClaimPaymentRequest) (*ClaimPaymentResponse, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method ClaimPayment not implemented")
 }
+func (UnimplementedArkServiceServer) SendTreeNonces(context.Context, *SendTreeNoncesRequest) (*SendTreeNoncesResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method SendTreeNonces not implemented")
+}
+func (UnimplementedArkServiceServer) SendTreeSignatures(context.Context, *SendTreeSignaturesRequest) (*SendTreeSignaturesResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method SendTreeSignatures not implemented")
+}
 func (UnimplementedArkServiceServer) FinalizePayment(context.Context, *FinalizePaymentRequest) (*FinalizePaymentResponse, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method FinalizePayment not implemented")
 }
@@ -279,6 +305,42 @@ func _ArkService_ClaimPayment_Handler(srv interface{}, ctx context.Context, dec
 	return interceptor(ctx, in, info, handler)
 }
 
+func _ArkService_SendTreeNonces_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(SendTreeNoncesRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ArkServiceServer).SendTreeNonces(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/ark.v1.ArkService/SendTreeNonces",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ArkServiceServer).SendTreeNonces(ctx, req.(*SendTreeNoncesRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _ArkService_SendTreeSignatures_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(SendTreeSignaturesRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(ArkServiceServer).SendTreeSignatures(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/ark.v1.ArkService/SendTreeSignatures",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(ArkServiceServer).SendTreeSignatures(ctx, req.(*SendTreeSignaturesRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 func _ArkService_FinalizePayment_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
 	in := new(FinalizePaymentRequest)
 	if err := dec(in); err != nil {
@@ -477,6 +539,14 @@ var ArkService_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "ClaimPayment",
 			Handler:    _ArkService_ClaimPayment_Handler,
 		},
+		{
+			MethodName: "SendTreeNonces",
+			Handler:    _ArkService_SendTreeNonces_Handler,
+		},
+		{
+			MethodName: "SendTreeSignatures",
+			Handler:    _ArkService_SendTreeSignatures_Handler,
+		},
 		{
 			MethodName: "FinalizePayment",
 			Handler:    _ArkService_FinalizePayment_Handler,

client/covenantless/claim.go

@@ -1,8 +1,11 @@
 package covenantless
 
 import (
+	"encoding/hex"
+
 	arkv1 "github.com/ark-network/ark/api-spec/protobuf/gen/ark/v1"
 	"github.com/ark-network/ark/client/utils"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/urfave/cli/v2"
 )
 
@@ -69,8 +72,19 @@ func selfTransferAllPendingPayments(
 		return err
 	}
 
+	ephemeralKey, err := secp256k1.GeneratePrivateKey()
+	if err != nil {
+		return err
+	}
+
+	pubkey := hex.EncodeToString(ephemeralKey.PubKey().SerializeCompressed())
+
 	registerResponse, err := client.RegisterPayment(
-		ctx.Context, &arkv1.RegisterPaymentRequest{Inputs: inputs},
+		ctx.Context,
+		&arkv1.RegisterPaymentRequest{
+			Inputs:          inputs,
+			EphemeralPubkey: &pubkey,
+		},
 	)
 	if err != nil {
 		return err
@@ -86,7 +100,7 @@ func selfTransferAllPendingPayments(
 
 	poolTxID, err := handleRoundStream(
 		ctx, client, registerResponse.GetId(),
-		pendingVtxos, secKey, receiversOutput,
+		pendingVtxos, secKey, receiversOutput, ephemeralKey,
 	)
 	if err != nil {
 		return err

client/covenantless/client.go

@@ -3,6 +3,7 @@ package covenantless
 import (
 	"bytes"
 	"context"
+	"encoding/hex"
 	"fmt"
 	"io"
 	"strings"
@@ -14,6 +15,7 @@ import (
 	"github.com/ark-network/ark/common/tree"
 	"github.com/btcsuite/btcd/btcec/v2/schnorr"
 	"github.com/btcsuite/btcd/btcutil/psbt"
+	"github.com/btcsuite/btcd/txscript"
 	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/urfave/cli/v2"
 	"google.golang.org/grpc"
@@ -220,12 +222,15 @@ func castCongestionTree(congestionTree tree.CongestionTree) *arkv1.Tree {
 func handleRoundStream(
 	ctx *cli.Context, client arkv1.ArkServiceClient, paymentID string,
 	vtxosToSign []vtxo, secKey *secp256k1.PrivateKey, receivers []*arkv1.Output,
+	ephemeralKey *secp256k1.PrivateKey,
 ) (poolTxID string, err error) {
 	stream, err := client.GetEventStream(ctx.Context, &arkv1.GetEventStreamRequest{})
 	if err != nil {
 		return "", err
 	}
 
+	myEphemeralPublicKey := hex.EncodeToString(ephemeralKey.PubKey().SerializeCompressed())
+
 	var pingStop func()
 	pingReq := &arkv1.PingRequest{
 		PaymentId: paymentID,
@@ -236,6 +241,8 @@ func handleRoundStream(
 
 	defer pingStop()
 
+	var treeSignerSession bitcointree.SignerSession
+
 	for {
 		event, err := stream.Recv()
 		if err == io.EOF {
@@ -250,6 +257,143 @@ func handleRoundStream(
 			return "", fmt.Errorf("round failed: %s", e.GetReason())
 		}
 
+		if e := event.GetRoundSigning(); e != nil {
+			pingStop()
+			fmt.Println("tree created, generating nonces...")
+
+			cosignersPubKeysHex := e.GetCosignersPubkeys()
+
+			cosigners := make([]*secp256k1.PublicKey, 0, len(cosignersPubKeysHex))
+
+			for _, pubkeyHex := range cosignersPubKeysHex {
+				pubkeyBytes, err := hex.DecodeString(pubkeyHex)
+				if err != nil {
+					return "", err
+				}
+
+				pubkey, err := secp256k1.ParsePubKey(pubkeyBytes)
+				if err != nil {
+					return "", err
+				}
+
+				cosigners = append(cosigners, pubkey)
+			}
+
+			congestionTree, err := toCongestionTree(e.GetUnsignedTree())
+			if err != nil {
+				return "", err
+			}
+
+			minRelayFee, err := utils.GetMinRelayFee(ctx)
+			if err != nil {
+				return "", err
+			}
+
+			aspPubkey, err := utils.GetAspPublicKey(ctx)
+			if err != nil {
+				return "", err
+			}
+
+			lifetime, err := utils.GetRoundLifetime(ctx)
+			if err != nil {
+				return "", err
+			}
+
+			sweepClosure := bitcointree.CSVSigClosure{
+				Pubkey:  aspPubkey,
+				Seconds: uint(lifetime),
+			}
+
+			sweepTapLeaf, err := sweepClosure.Leaf()
+			if err != nil {
+				return "", err
+			}
+
+			sweepTapTree := txscript.AssembleTaprootScriptTree(*sweepTapLeaf)
+			root := sweepTapTree.RootNode.TapHash()
+
+			treeSignerSession = bitcointree.NewTreeSignerSession(
+				ephemeralKey, congestionTree, int64(minRelayFee), root.CloneBytes(),
+			)
+
+			nonces, err := treeSignerSession.GetNonces()
+			if err != nil {
+				return "", err
+			}
+
+			if err := treeSignerSession.SetKeys(cosigners); err != nil {
+				return "", err
+			}
+
+			var nonceBuffer bytes.Buffer
+
+			if err := nonces.Encode(&nonceBuffer); err != nil {
+				return "", err
+			}
+
+			serializedNonces := hex.EncodeToString(nonceBuffer.Bytes())
+
+			if _, err := client.SendTreeNonces(ctx.Context, &arkv1.SendTreeNoncesRequest{
+				RoundId:    e.GetId(),
+				PublicKey:  myEphemeralPublicKey,
+				TreeNonces: serializedNonces,
+			}); err != nil {
+				return "", err
+			}
+
+			fmt.Println("nonces sent")
+
+			continue
+		}
+
+		if e := event.GetRoundSigningNoncesGenerated(); e != nil {
+			pingStop()
+			fmt.Println("nonces generated, signing the tree...")
+
+			if treeSignerSession == nil {
+				return "", fmt.Errorf("tree signer session not set")
+			}
+
+			combinedNoncesBytes, err := hex.DecodeString(e.GetTreeNonces())
+			if err != nil {
+				return "", err
+			}
+
+			combinedNonces, err := bitcointree.DecodeNonces(bytes.NewReader(combinedNoncesBytes))
+			if err != nil {
+				return "", err
+			}
+
+			if err := treeSignerSession.SetAggregatedNonces(combinedNonces); err != nil {
+				return "", err
+			}
+
+			sigs, err := treeSignerSession.Sign()
+			if err != nil {
+				return "", err
+			}
+
+			var sigBuffer bytes.Buffer
+
+			if err := sigs.Encode(&sigBuffer); err != nil {
+				return "", err
+			}
+
+			serializedSigs := hex.EncodeToString(sigBuffer.Bytes())
+
+			if _, err := client.SendTreeSignatures(ctx.Context, &arkv1.SendTreeSignaturesRequest{
+				RoundId:        e.GetId(),
+				TreeSignatures: serializedSigs,
+				PublicKey:      myEphemeralPublicKey,
+			}); err != nil {
+				return "", err
+			}
+
+			fmt.Println("tree signed")
+
+			continue
+		}
+
 		if e := event.GetRoundFinalization(); e != nil {
 			// stop pinging as soon as we receive some forfeit txs
 			pingStop()

client/covenantless/onboard.go

@@ -168,7 +168,11 @@ func (c *clArkBitcoinCLI) Onboard(ctx *cli.Context) error {
 		return err
 	}
 
-	if err := signer.SetKeys(cosigners, aggregatedNonces); err != nil {
+	if err := signer.SetKeys(cosigners); err != nil {
+		return err
+	}
+
+	if err := signer.SetAggregatedNonces(aggregatedNonces); err != nil {
 		return err
 	}
 

client/covenantless/redeem.go

@@ -2,6 +2,7 @@ package covenantless
 
 import (
 	"bufio"
+	"encoding/hex"
 	"fmt"
 	"log"
 	"os"
@@ -11,6 +12,7 @@ import (
 	arkv1 "github.com/ark-network/ark/api-spec/protobuf/gen/ark/v1"
 	"github.com/ark-network/ark/client/utils"
 	"github.com/btcsuite/btcd/btcutil"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/urfave/cli/v2"
 )
 
@@ -80,8 +82,16 @@ func collaborativeRedeem(
 		return err
 	}
 
+	ephemeralKey, err := secp256k1.GeneratePrivateKey()
+	if err != nil {
+		return err
+	}
+
+	pubkey := hex.EncodeToString(ephemeralKey.PubKey().SerializeCompressed())
+
 	registerResponse, err := client.RegisterPayment(ctx.Context, &arkv1.RegisterPaymentRequest{
-		Inputs: inputs,
+		Inputs:          inputs,
+		EphemeralPubkey: &pubkey,
 	})
 	if err != nil {
 		return err
@@ -102,6 +112,7 @@ func collaborativeRedeem(
 		selectedCoins,
 		secKey,
 		receivers,
+		ephemeralKey,
 	)
 	if err != nil {
 		return err

common/bitcointree/musig2.go

@@ -1,7 +1,9 @@
 package bitcointree
 
 import (
+	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"strings"
 
@@ -12,20 +14,45 @@ import (
 	"github.com/btcsuite/btcd/btcutil/psbt"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 )
 
 var (
 	ErrCongestionTreeNotSet = errors.New("congestion tree not set")
 	ErrAggregateKeyNotSet   = errors.New("aggregate key not set")
+
+	columnSeparator = byte('|')
+	rowSeparator    = byte('/')
 )
 
-type TreeNonces [][][66]byte // public nonces
+type Musig2Nonce struct {
+	PubNonce [66]byte
+}
+
+func (n *Musig2Nonce) Encode(w io.Writer) error {
+	_, err := w.Write(n.PubNonce[:])
+	return err
+}
+
+func (n *Musig2Nonce) Decode(r io.Reader) error {
+	bytes := make([]byte, 66)
+	_, err := r.Read(bytes)
+	if err != nil {
+		return err
+	}
+
+	n.PubNonce = [66]byte(bytes)
+	return nil
+}
+
+type TreeNonces [][]*Musig2Nonce // public nonces
 type TreePartialSigs [][]*musig2.PartialSignature
 
 type SignerSession interface {
-	GetNonces() (TreeNonces, error)               // generate of return cached nonce for this session
+	GetNonces() (TreeNonces, error)       // generate tree nonces for this session
-	SetKeys([]*btcec.PublicKey, TreeNonces) error // set the keys for this session (with the combined nonces)
+	SetKeys([]*btcec.PublicKey) error     // set the cosigner public keys for this session
-	Sign() (TreePartialSigs, error)               // sign the tree
+	SetAggregatedNonces(TreeNonces) error // set the aggregated nonces
+	Sign() (TreePartialSigs, error)       // sign the tree
 }
 
 type CoordinatorSession interface {
@@ -36,6 +63,34 @@ type CoordinatorSession interface {
 	SignTree() (tree.CongestionTree, error)
 }
 
+func (n TreeNonces) Encode(w io.Writer) error {
+	matrix, err := encodeMatrix(n)
+	if err != nil {
+		return err
+	}
+
+	_, err = w.Write(matrix)
+	return err
+}
+
+func DecodeNonces(r io.Reader) (TreeNonces, error) {
+	return decodeMatrix(func() *Musig2Nonce { return new(Musig2Nonce) }, r)
+}
+
+func (s TreePartialSigs) Encode(w io.Writer) error {
+	matrix, err := encodeMatrix(s)
+	if err != nil {
+		return err
+	}
+
+	_, err = w.Write(matrix)
+	return err
+}
+
+func DecodeSignatures(r io.Reader) (TreePartialSigs, error) {
+	return decodeMatrix(func() *musig2.PartialSignature { return new(musig2.PartialSignature) }, r)
+}
+
 func AggregateKeys(
 	pubkeys []*btcec.PublicKey,
 	scriptRoot []byte,
@@ -100,62 +155,6 @@ func ValidateTreeSigs(
 	return nil
 }
 
-func (n TreeNonces) Decode(r io.Reader, matrixFormat []int) error {
-	for i := 0; i < len(matrixFormat); i++ {
-		for j := 0; j < matrixFormat[i]; j++ {
-			// read 66 bytes
-			nonce := make([]byte, 66)
-			_, err := r.Read(nonce)
-			if err != nil {
-				return err
-			}
-
-			n[i][j] = [66]byte(nonce)
-		}
-	}
-
-	return nil
-}
-
-func (n TreeNonces) Encode(w io.Writer) error {
-	for i := 0; i < len(n); i++ {
-		for j := 0; j < len(n[i]); j++ {
-			nonce := n[i][j][:]
-			_, err := w.Write(nonce)
-			if err != nil {
-				return err
-			}
-		}
-	}
-
-	return nil
-}
-
-func (n TreePartialSigs) Decode(r io.Reader, matrixFormat []int) error {
-	for i := 0; i < len(matrixFormat); i++ {
-		for j := 0; j < matrixFormat[i]; j++ {
-			sig := &musig2.PartialSignature{}
-			if err := sig.Decode(r); err != nil {
-				return err
-			}
-		}
-	}
-
-	return nil
-}
-
-func (n TreePartialSigs) Encode(w io.Writer) error {
-	for i := 0; i < len(n); i++ {
-		for j := 0; j < len(n[i]); j++ {
-			if err := n[i][j].Encode(w); err != nil {
-				return err
-			}
-		}
-	}
-
-	return nil
-}
-
 func NewTreeSignerSession(
 	signer *btcec.PrivateKey,
 	congestionTree tree.CongestionTree,
@@ -221,9 +220,9 @@ func (t *treeSignerSession) GetNonces() (TreeNonces, error) {
 	nonces := make(TreeNonces, 0)
 
 	for _, level := range t.myNonces {
-		levelNonces := make([][66]byte, 0)
+		levelNonces := make([]*Musig2Nonce, 0)
 		for _, nonce := range level {
-			levelNonces = append(levelNonces, nonce.PubNonce)
+			levelNonces = append(levelNonces, &Musig2Nonce{nonce.PubNonce})
 		}
 		nonces = append(nonces, levelNonces)
 	}
@@ -231,15 +230,11 @@ func (t *treeSignerSession) GetNonces() (TreeNonces, error) {
 	return nonces, nil
 }
 
-func (t *treeSignerSession) SetKeys(keys []*btcec.PublicKey, nonces TreeNonces) error {
+func (t *treeSignerSession) SetKeys(keys []*btcec.PublicKey) error {
 	if t.keys != nil {
 		return errors.New("keys already set")
 	}
 
-	if t.aggregateNonces != nil {
-		return errors.New("nonces already set")
-	}
-
 	aggregateKey, err := AggregateKeys(keys, t.scriptRoot)
 	if err != nil {
 		return err
@@ -251,12 +246,20 @@ func (t *treeSignerSession) SetKeys(keys []*btcec.PublicKey, nonces TreeNonces)
 	}
 
 	t.prevoutFetcher = prevoutFetcher
-	t.aggregateNonces = nonces
 	t.keys = keys
 
 	return nil
 }
 
+func (t *treeSignerSession) SetAggregatedNonces(nonces TreeNonces) error {
+	if t.aggregateNonces != nil {
+		return errors.New("nonces already set")
+	}
+
+	t.aggregateNonces = nonces
+	return nil
+}
+
 func (t *treeSignerSession) Sign() (TreePartialSigs, error) {
 	if t.tree == nil {
 		return nil, ErrCongestionTreeNotSet
@@ -313,7 +316,7 @@ func (t *treeSignerSession) signPartial(partialTx *psbt.Packet, posx int, posy i
 	}
 
 	return musig2.Sign(
-		myNonce.SecNonce, seckey, aggregatedNonce, t.keys, [32]byte(message),
+		myNonce.SecNonce, seckey, aggregatedNonce.PubNonce, t.keys, [32]byte(message),
 		musig2.WithSortedKeys(), musig2.WithTaprootSignTweak(t.scriptRoot),
 	)
 }
@@ -390,12 +393,11 @@ func (t *treeCoordinatorSession) AggregateNonces() (TreeNonces, error) {
 	aggregatedNonces := make(TreeNonces, 0)
 
 	for i, level := range t.tree {
-		levelNonces := make([][66]byte, 0)
+		levelNonces := make([]*Musig2Nonce, 0)
 		for j := range level {
-
 			nonces := make([][66]byte, 0)
 			for _, n := range t.nonces {
-				nonces = append(nonces, n[i][j])
+				nonces = append(nonces, n[i][j].PubNonce)
 			}
 
 			aggregatedNonce, err := musig2.AggregateNonces(nonces)
@@ -403,7 +405,7 @@ func (t *treeCoordinatorSession) AggregateNonces() (TreeNonces, error) {
 				return nil, err
 			}
 
-			levelNonces = append(levelNonces, aggregatedNonce)
+			levelNonces = append(levelNonces, &Musig2Nonce{aggregatedNonce})
 		}
 
 		aggregatedNonces = append(aggregatedNonces, levelNonces)
@@ -414,12 +416,17 @@ func (t *treeCoordinatorSession) AggregateNonces() (TreeNonces, error) {
 
 // SignTree implements CoordinatorSession.
 func (t *treeCoordinatorSession) SignTree() (tree.CongestionTree, error) {
+	var missingSigs int
 	for _, sig := range t.sigs {
 		if sig == nil {
-			return nil, errors.New("signatures not set")
+			missingSigs++
 		}
 	}
 
+	if missingSigs > 0 {
+		return nil, fmt.Errorf("missing %d signature(s)", missingSigs)
+	}
+
 	aggregatedKey, err := AggregateKeys(t.keys, t.scriptRoot)
 	if err != nil {
 		return nil, err
@@ -432,9 +439,18 @@ func (t *treeCoordinatorSession) SignTree() (tree.CongestionTree, error) {
 				return nil, err
 			}
 
+			var combinedNonce *secp256k1.PublicKey
 			sigs := make([]*musig2.PartialSignature, 0)
 			for _, sig := range t.sigs {
-				sigs = append(sigs, sig[i][j])
+				s := sig[i][j]
+				if s.R != nil {
+					combinedNonce = s.R
+				}
+				sigs = append(sigs, s)
+			}
+
+			if combinedNonce == nil {
+				return nil, errors.New("missing combined nonce")
 			}
 
 			inputFetcher := t.prevoutFetcher(partialTx)
@@ -448,7 +464,7 @@ func (t *treeCoordinatorSession) SignTree() (tree.CongestionTree, error) {
 			)
 
 			combinedSig := musig2.CombineSigs(
-				sigs[0].R, sigs,
+				combinedNonce, sigs,
 				musig2.WithTaprootTweakedCombine([32]byte(message), t.keys, t.scriptRoot, true),
 			)
 			if err != nil {
@@ -507,3 +523,71 @@ type treePrevOutFetcher struct {
 func (f *treePrevOutFetcher) FetchPrevOutput(wire.OutPoint) *wire.TxOut {
 	return f.prevout
 }
+
+type writable interface {
+	Encode(w io.Writer) error
+}
+
+type readable interface {
+	Decode(r io.Reader) error
+}
+
+// encodeMatrix encode a matrix of serializable objects into a byte stream
+func encodeMatrix[T writable](matrix [][]T) ([]byte, error) {
+	var buf bytes.Buffer
+
+	for _, row := range matrix {
+		for _, cell := range row {
+			if err := buf.WriteByte(columnSeparator); err != nil {
+				return nil, err
+			}
+
+			if err := cell.Encode(&buf); err != nil {
+				return nil, err
+			}
+		}
+
+		if err := buf.WriteByte(rowSeparator); err != nil {
+			return nil, err
+		}
+	}
+
+	return buf.Bytes(), nil
+}
+
+// decodeMatrix decode a byte stream into a matrix of serializable objects
+func decodeMatrix[T readable](factory func() T, data io.Reader) ([][]T, error) {
+	matrix := make([][]T, 0)
+	row := make([]T, 0)
+
+	for {
+		separator := make([]byte, 1)
+
+		if _, err := data.Read(separator); err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, err
+		}
+
+		b := separator[0]
+
+		if b == rowSeparator {
+			matrix = append(matrix, row)
+			row = make([]T, 0)
+			continue
+		}
+
+		cell := factory()
+
+		if err := cell.Decode(data); err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, err
+		}
+		row = append(row, cell)
+	}
+
+	return matrix, nil
+}

common/bitcointree/musig2_test.go

@@ -1,7 +1,9 @@
 package bitcointree_test
 
 import (
+	"bytes"
 	"encoding/json"
+	"fmt"
 	"os"
 	"testing"
 
@@ -85,6 +87,31 @@ func TestRoundTripSignTree(t *testing.T) {
 		aspNonces, err := aspSession.GetNonces()
 		require.NoError(t, err)
 
+		s := bytes.NewBuffer(nil)
+
+		err = aspNonces[0][0].Encode(s)
+		require.NoError(t, err)
+
+		bitcointreeNonce := new(bitcointree.Musig2Nonce)
+		err = bitcointreeNonce.Decode(s)
+		require.NoError(t, err)
+
+		require.Equal(t, aspNonces[0][0], bitcointreeNonce)
+
+		var serializedNonces bytes.Buffer
+
+		err = aspNonces.Encode(&serializedNonces)
+		require.NoError(t, err)
+
+		decodedNonces, err := bitcointree.DecodeNonces(&serializedNonces)
+		require.NoError(t, err)
+
+		for i, nonces := range aspNonces {
+			for j, nonce := range nonces {
+				require.Equal(t, nonce.PubNonce, decodedNonces[i][j].PubNonce, fmt.Sprintf("matrix nonce not equal at index i: %d, j: %d", i, j))
+			}
+		}
+
 		err = aspCoordinator.AddNonce(alice.PubKey(), aliceNonces)
 		require.NoError(t, err)
 
@@ -101,18 +128,30 @@ func TestRoundTripSignTree(t *testing.T) {
 
 		err = aliceSession.SetKeys(
 			cosigners,
+		)
+		require.NoError(t, err)
+
+		err = aliceSession.SetAggregatedNonces(
 			aggregatedNonce,
 		)
 		require.NoError(t, err)
 
 		err = bobSession.SetKeys(
 			cosigners,
+		)
+		require.NoError(t, err)
+
+		err = bobSession.SetAggregatedNonces(
 			aggregatedNonce,
 		)
 		require.NoError(t, err)
 
 		err = aspSession.SetKeys(
 			cosigners,
+		)
+		require.NoError(t, err)
+
+		err = aspSession.SetAggregatedNonces(
 			aggregatedNonce,
 		)
 		require.NoError(t, err)
@@ -126,6 +165,22 @@ func TestRoundTripSignTree(t *testing.T) {
 		aspSig, err := aspSession.Sign()
 		require.NoError(t, err)
 
+		// check that the sigs are serializable
+
+		serializedSigs := bytes.NewBuffer(nil)
+
+		err = aspSig.Encode(serializedSigs)
+		require.NoError(t, err)
+
+		decodedSigs, err := bitcointree.DecodeSignatures(serializedSigs)
+		require.NoError(t, err)
+
+		for i, sigs := range aspSig {
+			for j, sig := range sigs {
+				require.Equal(t, sig.S, decodedSigs[i][j].S, fmt.Sprintf("matrix sig not equal at index i: %d, j: %d", i, j))
+			}
+		}
+
 		// coordinator receives the signatures and combines them
 		err = aspCoordinator.AddSig(alice.PubKey(), aliceSig)
 		require.NoError(t, err)

pkg/client-sdk/Makefile

@@ -3,7 +3,7 @@
 ## genrest: compiles rest client from stub with https://github.com/go-swagger/go-swagger
 genrest:
 	@echo "Generating rest client from stub..."
-	@swagger generate client -f ../../server/api-spec/openapi/swagger/ark/v1/service.swagger.json -t ./client/rest/service --client-package=arkservice
+	@swagger generate client -f ../../api-spec/openapi/swagger/ark/v1/service.swagger.json -t ./client/rest/service --client-package=arkservice
 
 ## test: runs unit tests
 test:

pkg/client-sdk/client/client.go

@@ -4,7 +4,9 @@ import (
 	"context"
 	"time"
 
+	"github.com/ark-network/ark/common/bitcointree"
 	"github.com/ark-network/ark/common/tree"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 )
 
 const (
@@ -25,7 +27,7 @@ type ASPClient interface {
 		ctx context.Context, tx, userPubkey string, congestionTree tree.CongestionTree,
 	) error
 	RegisterPayment(
-		ctx context.Context, inputs []VtxoKey,
+		ctx context.Context, inputs []VtxoKey, ephemeralPublicKey string,
 	) (string, error)
 	ClaimPayment(
 		ctx context.Context, paymentID string, outputs []Output,
@@ -33,7 +35,7 @@ type ASPClient interface {
 	GetEventStream(
 		ctx context.Context, paymentID string,
 	) (<-chan RoundEventChannel, error)
-	Ping(ctx context.Context, paymentID string) (*RoundFinalizationEvent, error)
+	Ping(ctx context.Context, paymentID string) (RoundEvent, error)
 	FinalizePayment(
 		ctx context.Context, signedForfeitTxs []string,
 	) error
@@ -43,6 +45,12 @@ type ASPClient interface {
 	CompletePayment(
 		ctx context.Context, signedRedeemTx string, signedUnconditionalForfeitTxs []string,
 	) error
+	SendTreeNonces(
+		ctx context.Context, roundID, cosignerPubkey string, nonces bitcointree.TreeNonces,
+	) error
+	SendTreeSignatures(
+		ctx context.Context, roundID, cosignerPubkey string, signatures bitcointree.TreePartialSigs,
+	) error
 	Close()
 }
 
@@ -139,3 +147,18 @@ type RoundFailedEvent struct {
 }
 
 func (e RoundFailedEvent) isRoundEvent() {}
+
+type RoundSigningStartedEvent struct {
+	ID                  string
+	UnsignedTree        tree.CongestionTree
+	CosignersPublicKeys []*secp256k1.PublicKey
+}
+
+func (e RoundSigningStartedEvent) isRoundEvent() {}
+
+type RoundSigningNoncesGeneratedEvent struct {
+	ID     string
+	Nonces bitcointree.TreeNonces
+}
+
+func (e RoundSigningNoncesGeneratedEvent) isRoundEvent() {}

pkg/client-sdk/client/grpc/client.go

@@ -1,15 +1,19 @@
 package grpcclient
 
 import (
+	"bytes"
 	"context"
+	"encoding/hex"
 	"fmt"
 	"strings"
 	"time"
 
 	arkv1 "github.com/ark-network/ark/api-spec/protobuf/gen/ark/v1"
+	"github.com/ark-network/ark/common/bitcointree"
 	"github.com/ark-network/ark/common/tree"
 	"github.com/ark-network/ark/pkg/client-sdk/client"
 	"github.com/ark-network/ark/pkg/client-sdk/internal/utils"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
@@ -73,7 +77,13 @@ func (a *grpcClient) GetEventStream(
 				return
 			}
 
-			a.eventsCh <- client.RoundEventChannel{Event: event{resp}.toRoundEvent()}
+			ev, err := event{resp}.toRoundEvent()
+			if err != nil {
+				a.eventsCh <- client.RoundEventChannel{Err: err}
+				return
+			}
+
+			a.eventsCh <- client.RoundEventChannel{Event: ev}
 		}
 	}()
 
@@ -146,11 +156,15 @@ func (a *grpcClient) Onboard(
 }
 
 func (a *grpcClient) RegisterPayment(
-	ctx context.Context, inputs []client.VtxoKey,
+	ctx context.Context, inputs []client.VtxoKey, ephemeralPublicKey string,
 ) (string, error) {
 	req := &arkv1.RegisterPaymentRequest{
 		Inputs: ins(inputs).toProto(),
 	}
+	if len(ephemeralPublicKey) > 0 {
+		req.EphemeralPubkey = &ephemeralPublicKey
+	}
+
 	resp, err := a.svc.RegisterPayment(ctx, req)
 	if err != nil {
 		return "", err
@@ -171,7 +185,7 @@ func (a *grpcClient) ClaimPayment(
 
 func (a *grpcClient) Ping(
 	ctx context.Context, paymentID string,
-) (*client.RoundFinalizationEvent, error) {
+) (client.RoundEvent, error) {
 	req := &arkv1.PingRequest{
 		PaymentId: paymentID,
 	}
@@ -179,14 +193,8 @@ func (a *grpcClient) Ping(
 	if err != nil {
 		return nil, err
 	}
-	event := resp.GetEvent()
+
-	return &client.RoundFinalizationEvent{
+	return event{resp}.toRoundEvent()
-		ID:         event.GetId(),
-		Tx:         event.GetPoolTx(),
-		ForfeitTxs: event.GetForfeitTxs(),
-		Tree:       treeFromProto{event.GetCongestionTree()}.parse(),
-		Connectors: event.GetConnectors(),
-	}, nil
 }
 
 func (a *grpcClient) FinalizePayment(
@@ -252,6 +260,54 @@ func (a *grpcClient) GetRoundByID(
 	}, nil
 }
 
+func (a *grpcClient) SendTreeNonces(
+	ctx context.Context, roundID, cosignerPubkey string, nonces bitcointree.TreeNonces,
+) error {
+	var nonceBuffer bytes.Buffer
+
+	if err := nonces.Encode(&nonceBuffer); err != nil {
+		return err
+	}
+
+	serializedNonces := hex.EncodeToString(nonceBuffer.Bytes())
+
+	req := &arkv1.SendTreeNoncesRequest{
+		RoundId:    roundID,
+		PublicKey:  cosignerPubkey,
+		TreeNonces: serializedNonces,
+	}
+
+	if _, err := a.svc.SendTreeNonces(ctx, req); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (a *grpcClient) SendTreeSignatures(
+	ctx context.Context, roundID, cosignerPubkey string, signatures bitcointree.TreePartialSigs,
+) error {
+	var sigsBuffer bytes.Buffer
+
+	if err := signatures.Encode(&sigsBuffer); err != nil {
+		return err
+	}
+
+	serializedSigs := hex.EncodeToString(sigsBuffer.Bytes())
+
+	req := &arkv1.SendTreeSignaturesRequest{
+		RoundId:        roundID,
+		PublicKey:      cosignerPubkey,
+		TreeSignatures: serializedSigs,
+	}
+
+	if _, err := a.svc.SendTreeSignatures(ctx, req); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 type out client.Output
 
 func (o out) toProto() *arkv1.Output {
@@ -271,16 +327,25 @@ func (o outs) toProto() []*arkv1.Output {
 	return list
 }
 
-type event struct {
+// wrapper for GetEventStreamResponse and PingResponse
-	*arkv1.GetEventStreamResponse
+type eventResponse interface {
+	GetRoundFailed() *arkv1.RoundFailed
+	GetRoundFinalization() *arkv1.RoundFinalizationEvent
+	GetRoundFinalized() *arkv1.RoundFinalizedEvent
+	GetRoundSigning() *arkv1.RoundSigningEvent
+	GetRoundSigningNoncesGenerated() *arkv1.RoundSigningNoncesGeneratedEvent
 }
 
-func (e event) toRoundEvent() client.RoundEvent {
+type event struct {
+	eventResponse
+}
+
+func (e event) toRoundEvent() (client.RoundEvent, error) {
 	if ee := e.GetRoundFailed(); ee != nil {
 		return client.RoundFailedEvent{
 			ID:     ee.GetId(),
 			Reason: ee.GetReason(),
-		}
+		}, nil
 	}
 	if ee := e.GetRoundFinalization(); ee != nil {
 		tree := treeFromProto{ee.GetCongestionTree()}.parse()
@@ -290,13 +355,49 @@ func (e event) toRoundEvent() client.RoundEvent {
 			ForfeitTxs: ee.GetForfeitTxs(),
 			Tree:       tree,
 			Connectors: ee.GetConnectors(),
+		}, nil
+	}
+
+	if ee := e.GetRoundFinalized(); ee != nil {
+		return client.RoundFinalizedEvent{
+			ID:   ee.GetId(),
+			Txid: ee.GetPoolTxid(),
+		}, nil
+	}
+
+	if ee := e.GetRoundSigning(); ee != nil {
+		pubkeys := make([]*secp256k1.PublicKey, 0, len(ee.GetCosignersPubkeys()))
+		for _, pubkey := range ee.GetCosignersPubkeys() {
+			p, err := hex.DecodeString(pubkey)
+			if err != nil {
+				return nil, err
+			}
+			pk, err := secp256k1.ParsePubKey(p)
+			if err != nil {
+				return nil, err
+			}
+			pubkeys = append(pubkeys, pk)
 		}
+
+		return client.RoundSigningStartedEvent{
+			ID:                  ee.GetId(),
+			UnsignedTree:        treeFromProto{ee.GetUnsignedTree()}.parse(),
+			CosignersPublicKeys: pubkeys,
+		}, nil
 	}
-	ee := e.GetRoundFinalized()
+
-	return client.RoundFinalizedEvent{
+	if ee := e.GetRoundSigningNoncesGenerated(); ee != nil {
-		ID:   ee.GetId(),
+		nonces, err := bitcointree.DecodeNonces(hex.NewDecoder(strings.NewReader(ee.GetTreeNonces())))
-		Txid: ee.GetPoolTxid(),
+		if err != nil {
+			return nil, err
+		}
+		return client.RoundSigningNoncesGeneratedEvent{
+			ID:     ee.GetId(),
+			Nonces: nonces,
+		}, nil
 	}
+
+	return nil, fmt.Errorf("unknown event")
 }
 
 type vtxo struct {

pkg/client-sdk/client/rest/client.go

@@ -1,7 +1,9 @@
 package restclient
 
 import (
+	"bytes"
 	"context"
+	"encoding/hex"
 	"fmt"
 	"net/url"
 	"strconv"
@@ -9,16 +11,16 @@ import (
 	"time"
 
 	arkv1 "github.com/ark-network/ark/api-spec/protobuf/gen/ark/v1"
+	"github.com/ark-network/ark/common/bitcointree"
 	"github.com/ark-network/ark/common/tree"
 	"github.com/ark-network/ark/pkg/client-sdk/client"
 	"github.com/ark-network/ark/pkg/client-sdk/client/rest/service/arkservice"
 	"github.com/ark-network/ark/pkg/client-sdk/client/rest/service/arkservice/ark_service"
 	"github.com/ark-network/ark/pkg/client-sdk/client/rest/service/models"
 	"github.com/ark-network/ark/pkg/client-sdk/internal/utils"
-	"github.com/btcsuite/btcd/btcutil/psbt"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	httptransport "github.com/go-openapi/runtime/client"
 	"github.com/go-openapi/strfmt"
-	"github.com/vulpemventures/go-elements/psetv2"
 )
 
 type restClient struct {
@@ -71,39 +73,7 @@ func (a *restClient) GetEventStream(
 
 				if event != nil {
 					a.eventsCh <- client.RoundEventChannel{
-						Event: *event,
+						Event: event,
-					}
-
-					for {
-						roundID := event.ID
-						round, err := a.GetRoundByID(ctx, roundID)
-						if err != nil {
-							a.eventsCh <- client.RoundEventChannel{
-								Err: err,
-							}
-							return
-						}
-
-						if round.Stage == client.RoundStageFinalized {
-							a.eventsCh <- client.RoundEventChannel{
-								Event: client.RoundFinalizedEvent{
-									ID:   roundID,
-									Txid: getTxid(round.Tx),
-								},
-							}
-							return
-						}
-
-						if round.Stage == client.RoundStageFailed {
-							a.eventsCh <- client.RoundEventChannel{
-								Event: client.RoundFailedEvent{
-									ID: roundID,
-								},
-							}
-							return
-						}
-
-						time.Sleep(1 * time.Second)
 					}
 				}
 
@@ -286,7 +256,7 @@ func (a *restClient) Onboard(
 }
 
 func (a *restClient) RegisterPayment(
-	ctx context.Context, inputs []client.VtxoKey,
+	ctx context.Context, inputs []client.VtxoKey, ephemeralPublicKey string,
 ) (string, error) {
 	ins := make([]*models.V1Input, 0, len(inputs))
 	for _, i := range inputs {
@@ -295,11 +265,15 @@ func (a *restClient) RegisterPayment(
 			Vout: int64(i.VOut),
 		})
 	}
-	body := models.V1RegisterPaymentRequest{
+	body := &models.V1RegisterPaymentRequest{
 		Inputs: ins,
 	}
+	if len(ephemeralPublicKey) > 0 {
+		body.EphemeralPubkey = ephemeralPublicKey
+	}
+
 	resp, err := a.svc.ArkServiceRegisterPayment(
-		ark_service.NewArkServiceRegisterPaymentParams().WithBody(&body),
+		ark_service.NewArkServiceRegisterPaymentParams().WithBody(body),
 	)
 	if err != nil {
 		return "", err
@@ -331,7 +305,7 @@ func (a *restClient) ClaimPayment(
 
 func (a *restClient) Ping(
 	ctx context.Context, paymentID string,
-) (*client.RoundFinalizationEvent, error) {
+) (client.RoundEvent, error) {
 	r := ark_service.NewArkServicePingParams()
 	r.SetPaymentID(paymentID)
 	resp, err := a.svc.ArkServicePing(r)
@@ -339,18 +313,65 @@ func (a *restClient) Ping(
 		return nil, err
 	}
 
-	var event *client.RoundFinalizationEvent
+	payload := resp.Payload
-	if resp.Payload.Event != nil {
+
-		event = &client.RoundFinalizationEvent{
+	if e := payload.RoundFailed; e != nil {
-			ID:         resp.Payload.Event.ID,
+		return client.RoundFailedEvent{
-			Tx:         resp.Payload.Event.PoolTx,
+			ID:     e.ID,
-			ForfeitTxs: resp.Payload.Event.ForfeitTxs,
+			Reason: e.Reason,
-			Tree:       treeFromProto{resp.Payload.Event.CongestionTree}.parse(),
+		}, nil
-			Connectors: resp.Payload.Event.Connectors,
+	}
-		}
+	if e := payload.RoundFinalization; e != nil {
+		tree := treeFromProto{e.CongestionTree}.parse()
+		return client.RoundFinalizationEvent{
+			ID:         e.ID,
+			Tx:         e.PoolTx,
+			ForfeitTxs: e.ForfeitTxs,
+			Tree:       tree,
+			Connectors: e.Connectors,
+		}, nil
 	}
 
-	return event, nil
+	if e := payload.RoundFinalized; e != nil {
+		return client.RoundFinalizedEvent{
+			ID:   e.ID,
+			Txid: e.PoolTxid,
+		}, nil
+	}
+
+	if e := payload.RoundSigning; e != nil {
+		pubkeys := make([]*secp256k1.PublicKey, 0, len(e.CosignersPubkeys))
+		for _, pubkey := range e.CosignersPubkeys {
+			p, err := hex.DecodeString(pubkey)
+			if err != nil {
+				return nil, err
+			}
+			pk, err := secp256k1.ParsePubKey(p)
+			if err != nil {
+				return nil, err
+			}
+			pubkeys = append(pubkeys, pk)
+		}
+
+		return client.RoundSigningStartedEvent{
+			ID:                  e.ID,
+			UnsignedTree:        treeFromProto{e.UnsignedTree}.parse(),
+			CosignersPublicKeys: pubkeys,
+		}, nil
+	}
+
+	if e := payload.RoundSigningNoncesGenerated; e != nil {
+		nonces, err := bitcointree.DecodeNonces(hex.NewDecoder(strings.NewReader(e.TreeNonces)))
+		if err != nil {
+			return nil, err
+		}
+		return client.RoundSigningNoncesGeneratedEvent{
+			ID:     e.ID,
+			Nonces: nonces,
+		}, nil
+	}
+
+	return nil, nil
 }
 
 func (a *restClient) FinalizePayment(
@@ -454,6 +475,58 @@ func (a *restClient) GetRoundByID(
 	}, nil
 }
 
+func (a *restClient) SendTreeNonces(
+	ctx context.Context, roundID, cosignerPubkey string, nonces bitcointree.TreeNonces,
+) error {
+	var nonceBuffer bytes.Buffer
+
+	if err := nonces.Encode(&nonceBuffer); err != nil {
+		return err
+	}
+
+	serializedNonces := hex.EncodeToString(nonceBuffer.Bytes())
+
+	body := &models.V1SendTreeNoncesRequest{
+		RoundID:    roundID,
+		PublicKey:  cosignerPubkey,
+		TreeNonces: serializedNonces,
+	}
+
+	if _, err := a.svc.ArkServiceSendTreeNonces(
+		ark_service.NewArkServiceSendTreeNoncesParams().WithBody(body),
+	); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (a *restClient) SendTreeSignatures(
+	ctx context.Context, roundID, cosignerPubkey string, signatures bitcointree.TreePartialSigs,
+) error {
+	var sigsBuffer bytes.Buffer
+
+	if err := signatures.Encode(&sigsBuffer); err != nil {
+		return err
+	}
+
+	serializedSigs := hex.EncodeToString(sigsBuffer.Bytes())
+
+	body := &models.V1SendTreeSignaturesRequest{
+		RoundID:        roundID,
+		PublicKey:      cosignerPubkey,
+		TreeSignatures: serializedSigs,
+	}
+
+	if _, err := a.svc.ArkServiceSendTreeSignatures(
+		ark_service.NewArkServiceSendTreeSignaturesParams().WithBody(body),
+	); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func newRestClient(
 	serviceURL string,
 ) (ark_service.ClientService, error) {
@@ -551,13 +624,3 @@ func (t treeToProto) parse() *models.V1Tree {
 		Levels: levels,
 	}
 }
-
-func getTxid(tx string) string {
-	if ptx, _ := psetv2.NewPsetFromBase64(tx); ptx != nil {
-		utx, _ := ptx.UnsignedTx()
-		return utx.TxHash().String()
-	}
-
-	ptx, _ := psbt.NewFromRawBytes(strings.NewReader(tx), true)
-	return ptx.UnsignedTx.TxID()
-}

pkg/client-sdk/client/rest/service/arkservice/ark_service/ark_service_client.go

@@ -78,6 +78,10 @@ type ClientService interface {
 
 	ArkServiceRegisterPayment(params *ArkServiceRegisterPaymentParams, opts ...ClientOption) (*ArkServiceRegisterPaymentOK, error)
 
+	ArkServiceSendTreeNonces(params *ArkServiceSendTreeNoncesParams, opts ...ClientOption) (*ArkServiceSendTreeNoncesOK, error)
+
+	ArkServiceSendTreeSignatures(params *ArkServiceSendTreeSignaturesParams, opts ...ClientOption) (*ArkServiceSendTreeSignaturesOK, error)
+
 	SetTransport(transport runtime.ClientTransport)
 }
 
@@ -304,7 +308,7 @@ func (a *Client) ArkServiceGetInfo(params *ArkServiceGetInfoParams, opts ...Clie
 }
 
 /*
-ArkServiceGetRound ts o d o b t c sign tree rpc
+ArkServiceGetRound ark service get round API
 */
 func (a *Client) ArkServiceGetRound(params *ArkServiceGetRoundParams, opts ...ClientOption) (*ArkServiceGetRoundOK, error) {
 	// TODO: Validate the params before sending
@@ -525,6 +529,80 @@ func (a *Client) ArkServiceRegisterPayment(params *ArkServiceRegisterPaymentPara
 	return nil, runtime.NewAPIError("unexpected success response: content available as default response in error", unexpectedSuccess, unexpectedSuccess.Code())
 }
 
+/*
+ArkServiceSendTreeNonces ark service send tree nonces API
+*/
+func (a *Client) ArkServiceSendTreeNonces(params *ArkServiceSendTreeNoncesParams, opts ...ClientOption) (*ArkServiceSendTreeNoncesOK, error) {
+	// TODO: Validate the params before sending
+	if params == nil {
+		params = NewArkServiceSendTreeNoncesParams()
+	}
+	op := &runtime.ClientOperation{
+		ID:                 "ArkService_SendTreeNonces",
+		Method:             "POST",
+		PathPattern:        "/v1/payment/tree/nonces",
+		ProducesMediaTypes: []string{"application/json"},
+		ConsumesMediaTypes: []string{"application/json"},
+		Schemes:            []string{"http"},
+		Params:             params,
+		Reader:             &ArkServiceSendTreeNoncesReader{formats: a.formats},
+		Context:            params.Context,
+		Client:             params.HTTPClient,
+	}
+	for _, opt := range opts {
+		opt(op)
+	}
+
+	result, err := a.transport.Submit(op)
+	if err != nil {
+		return nil, err
+	}
+	success, ok := result.(*ArkServiceSendTreeNoncesOK)
+	if ok {
+		return success, nil
+	}
+	// unexpected success response
+	unexpectedSuccess := result.(*ArkServiceSendTreeNoncesDefault)
+	return nil, runtime.NewAPIError("unexpected success response: content available as default response in error", unexpectedSuccess, unexpectedSuccess.Code())
+}
+
+/*
+ArkServiceSendTreeSignatures ark service send tree signatures API
+*/
+func (a *Client) ArkServiceSendTreeSignatures(params *ArkServiceSendTreeSignaturesParams, opts ...ClientOption) (*ArkServiceSendTreeSignaturesOK, error) {
+	// TODO: Validate the params before sending
+	if params == nil {
+		params = NewArkServiceSendTreeSignaturesParams()
+	}
+	op := &runtime.ClientOperation{
+		ID:                 "ArkService_SendTreeSignatures",
+		Method:             "POST",
+		PathPattern:        "/v1/payment/tree/signatures",
+		ProducesMediaTypes: []string{"application/json"},
+		ConsumesMediaTypes: []string{"application/json"},
+		Schemes:            []string{"http"},
+		Params:             params,
+		Reader:             &ArkServiceSendTreeSignaturesReader{formats: a.formats},
+		Context:            params.Context,
+		Client:             params.HTTPClient,
+	}
+	for _, opt := range opts {
+		opt(op)
+	}
+
+	result, err := a.transport.Submit(op)
+	if err != nil {
+		return nil, err
+	}
+	success, ok := result.(*ArkServiceSendTreeSignaturesOK)
+	if ok {
+		return success, nil
+	}
+	// unexpected success response
+	unexpectedSuccess := result.(*ArkServiceSendTreeSignaturesDefault)
+	return nil, runtime.NewAPIError("unexpected success response: content available as default response in error", unexpectedSuccess, unexpectedSuccess.Code())
+}
+
 // SetTransport changes the transport on the client
 func (a *Client) SetTransport(transport runtime.ClientTransport) {
 	a.transport = transport

pkg/client-sdk/client/rest/service/arkservice/ark_service/ark_service_send_tree_nonces_parameters.go

@@ -0,0 +1,150 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package ark_service
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"github.com/go-openapi/errors"
+	"github.com/go-openapi/runtime"
+	cr "github.com/go-openapi/runtime/client"
+	"github.com/go-openapi/strfmt"
+
+	"github.com/ark-network/ark/pkg/client-sdk/client/rest/service/models"
+)
+
+// NewArkServiceSendTreeNoncesParams creates a new ArkServiceSendTreeNoncesParams object,
+// with the default timeout for this client.
+//
+// Default values are not hydrated, since defaults are normally applied by the API server side.
+//
+// To enforce default values in parameter, use SetDefaults or WithDefaults.
+func NewArkServiceSendTreeNoncesParams() *ArkServiceSendTreeNoncesParams {
+	return &ArkServiceSendTreeNoncesParams{
+		timeout: cr.DefaultTimeout,
+	}
+}
+
+// NewArkServiceSendTreeNoncesParamsWithTimeout creates a new ArkServiceSendTreeNoncesParams object
+// with the ability to set a timeout on a request.
+func NewArkServiceSendTreeNoncesParamsWithTimeout(timeout time.Duration) *ArkServiceSendTreeNoncesParams {
+	return &ArkServiceSendTreeNoncesParams{
+		timeout: timeout,
+	}
+}
+
+// NewArkServiceSendTreeNoncesParamsWithContext creates a new ArkServiceSendTreeNoncesParams object
+// with the ability to set a context for a request.
+func NewArkServiceSendTreeNoncesParamsWithContext(ctx context.Context) *ArkServiceSendTreeNoncesParams {
+	return &ArkServiceSendTreeNoncesParams{
+		Context: ctx,
+	}
+}
+
+// NewArkServiceSendTreeNoncesParamsWithHTTPClient creates a new ArkServiceSendTreeNoncesParams object
+// with the ability to set a custom HTTPClient for a request.
+func NewArkServiceSendTreeNoncesParamsWithHTTPClient(client *http.Client) *ArkServiceSendTreeNoncesParams {
+	return &ArkServiceSendTreeNoncesParams{
+		HTTPClient: client,
+	}
+}
+
+/*
+ArkServiceSendTreeNoncesParams contains all the parameters to send to the API endpoint
+
+	for the ark service send tree nonces operation.
+
+	Typically these are written to a http.Request.
+*/
+type ArkServiceSendTreeNoncesParams struct {
+
+	// Body.
+	Body *models.V1SendTreeNoncesRequest
+
+	timeout    time.Duration
+	Context    context.Context
+	HTTPClient *http.Client
+}
+
+// WithDefaults hydrates default values in the ark service send tree nonces params (not the query body).
+//
+// All values with no default are reset to their zero value.
+func (o *ArkServiceSendTreeNoncesParams) WithDefaults() *ArkServiceSendTreeNoncesParams {
+	o.SetDefaults()
+	return o
+}
+
+// SetDefaults hydrates default values in the ark service send tree nonces params (not the query body).
+//
+// All values with no default are reset to their zero value.
+func (o *ArkServiceSendTreeNoncesParams) SetDefaults() {
+	// no default values defined for this parameter
+}
+
+// WithTimeout adds the timeout to the ark service send tree nonces params
+func (o *ArkServiceSendTreeNoncesParams) WithTimeout(timeout time.Duration) *ArkServiceSendTreeNoncesParams {
+	o.SetTimeout(timeout)
+	return o
+}
+
+// SetTimeout adds the timeout to the ark service send tree nonces params
+func (o *ArkServiceSendTreeNoncesParams) SetTimeout(timeout time.Duration) {
+	o.timeout = timeout
+}
+
+// WithContext adds the context to the ark service send tree nonces params
+func (o *ArkServiceSendTreeNoncesParams) WithContext(ctx context.Context) *ArkServiceSendTreeNoncesParams {
+	o.SetContext(ctx)
+	return o
+}
+
+// SetContext adds the context to the ark service send tree nonces params
+func (o *ArkServiceSendTreeNoncesParams) SetContext(ctx context.Context) {
+	o.Context = ctx
+}
+
+// WithHTTPClient adds the HTTPClient to the ark service send tree nonces params
+func (o *ArkServiceSendTreeNoncesParams) WithHTTPClient(client *http.Client) *ArkServiceSendTreeNoncesParams {
+	o.SetHTTPClient(client)
+	return o
+}
+
+// SetHTTPClient adds the HTTPClient to the ark service send tree nonces params
+func (o *ArkServiceSendTreeNoncesParams) SetHTTPClient(client *http.Client) {
+	o.HTTPClient = client
+}
+
+// WithBody adds the body to the ark service send tree nonces params
+func (o *ArkServiceSendTreeNoncesParams) WithBody(body *models.V1SendTreeNoncesRequest) *ArkServiceSendTreeNoncesParams {
+	o.SetBody(body)
+	return o
+}
+
+// SetBody adds the body to the ark service send tree nonces params
+func (o *ArkServiceSendTreeNoncesParams) SetBody(body *models.V1SendTreeNoncesRequest) {
+	o.Body = body
+}
+
+// WriteToRequest writes these params to a swagger request
+func (o *ArkServiceSendTreeNoncesParams) WriteToRequest(r runtime.ClientRequest, reg strfmt.Registry) error {
+
+	if err := r.SetTimeout(o.timeout); err != nil {
+		return err
+	}
+	var res []error
+	if o.Body != nil {
+		if err := r.SetBodyParam(o.Body); err != nil {
+			return err
+		}
+	}
+
+	if len(res) > 0 {
+		return errors.CompositeValidationError(res...)
+	}
+	return nil
+}

pkg/client-sdk/client/rest/service/arkservice/ark_service/ark_service_send_tree_nonces_responses.go

@@ -0,0 +1,185 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package ark_service
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+
+	"github.com/go-openapi/runtime"
+	"github.com/go-openapi/strfmt"
+
+	"github.com/ark-network/ark/pkg/client-sdk/client/rest/service/models"
+)
+
+// ArkServiceSendTreeNoncesReader is a Reader for the ArkServiceSendTreeNonces structure.
+type ArkServiceSendTreeNoncesReader struct {
+	formats strfmt.Registry
+}
+
+// ReadResponse reads a server response into the received o.
+func (o *ArkServiceSendTreeNoncesReader) ReadResponse(response runtime.ClientResponse, consumer runtime.Consumer) (interface{}, error) {
+	switch response.Code() {
+	case 200:
+		result := NewArkServiceSendTreeNoncesOK()
+		if err := result.readResponse(response, consumer, o.formats); err != nil {
+			return nil, err
+		}
+		return result, nil
+	default:
+		result := NewArkServiceSendTreeNoncesDefault(response.Code())
+		if err := result.readResponse(response, consumer, o.formats); err != nil {
+			return nil, err
+		}
+		if response.Code()/100 == 2 {
+			return result, nil
+		}
+		return nil, result
+	}
+}
+
+// NewArkServiceSendTreeNoncesOK creates a ArkServiceSendTreeNoncesOK with default headers values
+func NewArkServiceSendTreeNoncesOK() *ArkServiceSendTreeNoncesOK {
+	return &ArkServiceSendTreeNoncesOK{}
+}
+
+/*
+ArkServiceSendTreeNoncesOK describes a response with status code 200, with default header values.
+
+A successful response.
+*/
+type ArkServiceSendTreeNoncesOK struct {
+	Payload models.V1SendTreeNoncesResponse
+}
+
+// IsSuccess returns true when this ark service send tree nonces o k response has a 2xx status code
+func (o *ArkServiceSendTreeNoncesOK) IsSuccess() bool {
+	return true
+}
+
+// IsRedirect returns true when this ark service send tree nonces o k response has a 3xx status code
+func (o *ArkServiceSendTreeNoncesOK) IsRedirect() bool {
+	return false
+}
+
+// IsClientError returns true when this ark service send tree nonces o k response has a 4xx status code
+func (o *ArkServiceSendTreeNoncesOK) IsClientError() bool {
+	return false
+}
+
+// IsServerError returns true when this ark service send tree nonces o k response has a 5xx status code
+func (o *ArkServiceSendTreeNoncesOK) IsServerError() bool {
+	return false
+}
+
+// IsCode returns true when this ark service send tree nonces o k response a status code equal to that given
+func (o *ArkServiceSendTreeNoncesOK) IsCode(code int) bool {
+	return code == 200
+}
+
+// Code gets the status code for the ark service send tree nonces o k response
+func (o *ArkServiceSendTreeNoncesOK) Code() int {
+	return 200
+}
+
+func (o *ArkServiceSendTreeNoncesOK) Error() string {
+	payload, _ := json.Marshal(o.Payload)
+	return fmt.Sprintf("[POST /v1/payment/tree/nonces][%d] arkServiceSendTreeNoncesOK %s", 200, payload)
+}
+
+func (o *ArkServiceSendTreeNoncesOK) String() string {
+	payload, _ := json.Marshal(o.Payload)
+	return fmt.Sprintf("[POST /v1/payment/tree/nonces][%d] arkServiceSendTreeNoncesOK %s", 200, payload)
+}
+
+func (o *ArkServiceSendTreeNoncesOK) GetPayload() models.V1SendTreeNoncesResponse {
+	return o.Payload
+}
+
+func (o *ArkServiceSendTreeNoncesOK) readResponse(response runtime.ClientResponse, consumer runtime.Consumer, formats strfmt.Registry) error {
+
+	// response payload
+	if err := consumer.Consume(response.Body(), &o.Payload); err != nil && err != io.EOF {
+		return err
+	}
+
+	return nil
+}
+
+// NewArkServiceSendTreeNoncesDefault creates a ArkServiceSendTreeNoncesDefault with default headers values
+func NewArkServiceSendTreeNoncesDefault(code int) *ArkServiceSendTreeNoncesDefault {
+	return &ArkServiceSendTreeNoncesDefault{
+		_statusCode: code,
+	}
+}
+
+/*
+ArkServiceSendTreeNoncesDefault describes a response with status code -1, with default header values.
+
+An unexpected error response.
+*/
+type ArkServiceSendTreeNoncesDefault struct {
+	_statusCode int
+
+	Payload *models.RPCStatus
+}
+
+// IsSuccess returns true when this ark service send tree nonces default response has a 2xx status code
+func (o *ArkServiceSendTreeNoncesDefault) IsSuccess() bool {
+	return o._statusCode/100 == 2
+}
+
+// IsRedirect returns true when this ark service send tree nonces default response has a 3xx status code
+func (o *ArkServiceSendTreeNoncesDefault) IsRedirect() bool {
+	return o._statusCode/100 == 3
+}
+
+// IsClientError returns true when this ark service send tree nonces default response has a 4xx status code
+func (o *ArkServiceSendTreeNoncesDefault) IsClientError() bool {
+	return o._statusCode/100 == 4
+}
+
+// IsServerError returns true when this ark service send tree nonces default response has a 5xx status code
+func (o *ArkServiceSendTreeNoncesDefault) IsServerError() bool {
+	return o._statusCode/100 == 5
+}
+
+// IsCode returns true when this ark service send tree nonces default response a status code equal to that given
+func (o *ArkServiceSendTreeNoncesDefault) IsCode(code int) bool {
+	return o._statusCode == code
+}
+
+// Code gets the status code for the ark service send tree nonces default response
+func (o *ArkServiceSendTreeNoncesDefault) Code() int {
+	return o._statusCode
+}
+
+func (o *ArkServiceSendTreeNoncesDefault) Error() string {
+	payload, _ := json.Marshal(o.Payload)
+	return fmt.Sprintf("[POST /v1/payment/tree/nonces][%d] ArkService_SendTreeNonces default %s", o._statusCode, payload)
+}
+
+func (o *ArkServiceSendTreeNoncesDefault) String() string {
+	payload, _ := json.Marshal(o.Payload)
+	return fmt.Sprintf("[POST /v1/payment/tree/nonces][%d] ArkService_SendTreeNonces default %s", o._statusCode, payload)
+}
+
+func (o *ArkServiceSendTreeNoncesDefault) GetPayload() *models.RPCStatus {
+	return o.Payload
+}
+
+func (o *ArkServiceSendTreeNoncesDefault) readResponse(response runtime.ClientResponse, consumer runtime.Consumer, formats strfmt.Registry) error {
+
+	o.Payload = new(models.RPCStatus)
+
+	// response payload
+	if err := consumer.Consume(response.Body(), o.Payload); err != nil && err != io.EOF {
+		return err
+	}
+
+	return nil
+}

pkg/client-sdk/client/rest/service/arkservice/ark_service/ark_service_send_tree_signatures_parameters.go

@@ -0,0 +1,150 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package ark_service
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+import (
+	"context"
+	"net/http"
+	"time"
+
+	"github.com/go-openapi/errors"
+	"github.com/go-openapi/runtime"
+	cr "github.com/go-openapi/runtime/client"
+	"github.com/go-openapi/strfmt"
+
+	"github.com/ark-network/ark/pkg/client-sdk/client/rest/service/models"
+)
+
+// NewArkServiceSendTreeSignaturesParams creates a new ArkServiceSendTreeSignaturesParams object,
+// with the default timeout for this client.
+//
+// Default values are not hydrated, since defaults are normally applied by the API server side.
+//
+// To enforce default values in parameter, use SetDefaults or WithDefaults.
+func NewArkServiceSendTreeSignaturesParams() *ArkServiceSendTreeSignaturesParams {
+	return &ArkServiceSendTreeSignaturesParams{
+		timeout: cr.DefaultTimeout,
+	}
+}
+
+// NewArkServiceSendTreeSignaturesParamsWithTimeout creates a new ArkServiceSendTreeSignaturesParams object
+// with the ability to set a timeout on a request.
+func NewArkServiceSendTreeSignaturesParamsWithTimeout(timeout time.Duration) *ArkServiceSendTreeSignaturesParams {
+	return &ArkServiceSendTreeSignaturesParams{
+		timeout: timeout,
+	}
+}
+
+// NewArkServiceSendTreeSignaturesParamsWithContext creates a new ArkServiceSendTreeSignaturesParams object
+// with the ability to set a context for a request.
+func NewArkServiceSendTreeSignaturesParamsWithContext(ctx context.Context) *ArkServiceSendTreeSignaturesParams {
+	return &ArkServiceSendTreeSignaturesParams{
+		Context: ctx,
+	}
+}
+
+// NewArkServiceSendTreeSignaturesParamsWithHTTPClient creates a new ArkServiceSendTreeSignaturesParams object
+// with the ability to set a custom HTTPClient for a request.
+func NewArkServiceSendTreeSignaturesParamsWithHTTPClient(client *http.Client) *ArkServiceSendTreeSignaturesParams {
+	return &ArkServiceSendTreeSignaturesParams{
+		HTTPClient: client,
+	}
+}
+
+/*
+ArkServiceSendTreeSignaturesParams contains all the parameters to send to the API endpoint
+
+	for the ark service send tree signatures operation.
+
+	Typically these are written to a http.Request.
+*/
+type ArkServiceSendTreeSignaturesParams struct {
+
+	// Body.
+	Body *models.V1SendTreeSignaturesRequest
+
+	timeout    time.Duration
+	Context    context.Context
+	HTTPClient *http.Client
+}
+
+// WithDefaults hydrates default values in the ark service send tree signatures params (not the query body).
+//
+// All values with no default are reset to their zero value.
+func (o *ArkServiceSendTreeSignaturesParams) WithDefaults() *ArkServiceSendTreeSignaturesParams {
+	o.SetDefaults()
+	return o
+}
+
+// SetDefaults hydrates default values in the ark service send tree signatures params (not the query body).
+//
+// All values with no default are reset to their zero value.
+func (o *ArkServiceSendTreeSignaturesParams) SetDefaults() {
+	// no default values defined for this parameter
+}
+
+// WithTimeout adds the timeout to the ark service send tree signatures params
+func (o *ArkServiceSendTreeSignaturesParams) WithTimeout(timeout time.Duration) *ArkServiceSendTreeSignaturesParams {
+	o.SetTimeout(timeout)
+	return o
+}
+
+// SetTimeout adds the timeout to the ark service send tree signatures params
+func (o *ArkServiceSendTreeSignaturesParams) SetTimeout(timeout time.Duration) {
+	o.timeout = timeout
+}
+
+// WithContext adds the context to the ark service send tree signatures params
+func (o *ArkServiceSendTreeSignaturesParams) WithContext(ctx context.Context) *ArkServiceSendTreeSignaturesParams {
+	o.SetContext(ctx)
+	return o
+}
+
+// SetContext adds the context to the ark service send tree signatures params
+func (o *ArkServiceSendTreeSignaturesParams) SetContext(ctx context.Context) {
+	o.Context = ctx
+}
+
+// WithHTTPClient adds the HTTPClient to the ark service send tree signatures params
+func (o *ArkServiceSendTreeSignaturesParams) WithHTTPClient(client *http.Client) *ArkServiceSendTreeSignaturesParams {
+	o.SetHTTPClient(client)
+	return o
+}
+
+// SetHTTPClient adds the HTTPClient to the ark service send tree signatures params
+func (o *ArkServiceSendTreeSignaturesParams) SetHTTPClient(client *http.Client) {
+	o.HTTPClient = client
+}
+
+// WithBody adds the body to the ark service send tree signatures params
+func (o *ArkServiceSendTreeSignaturesParams) WithBody(body *models.V1SendTreeSignaturesRequest) *ArkServiceSendTreeSignaturesParams {
+	o.SetBody(body)
+	return o
+}
+
+// SetBody adds the body to the ark service send tree signatures params
+func (o *ArkServiceSendTreeSignaturesParams) SetBody(body *models.V1SendTreeSignaturesRequest) {
+	o.Body = body
+}
+
+// WriteToRequest writes these params to a swagger request
+func (o *ArkServiceSendTreeSignaturesParams) WriteToRequest(r runtime.ClientRequest, reg strfmt.Registry) error {
+
+	if err := r.SetTimeout(o.timeout); err != nil {
+		return err
+	}
+	var res []error
+	if o.Body != nil {
+		if err := r.SetBodyParam(o.Body); err != nil {
+			return err
+		}
+	}
+
+	if len(res) > 0 {
+		return errors.CompositeValidationError(res...)
+	}
+	return nil
+}

pkg/client-sdk/client/rest/service/arkservice/ark_service/ark_service_send_tree_signatures_responses.go

@@ -0,0 +1,185 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package ark_service
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+
+	"github.com/go-openapi/runtime"
+	"github.com/go-openapi/strfmt"
+
+	"github.com/ark-network/ark/pkg/client-sdk/client/rest/service/models"
+)
+
+// ArkServiceSendTreeSignaturesReader is a Reader for the ArkServiceSendTreeSignatures structure.
+type ArkServiceSendTreeSignaturesReader struct {
+	formats strfmt.Registry
+}
+
+// ReadResponse reads a server response into the received o.
+func (o *ArkServiceSendTreeSignaturesReader) ReadResponse(response runtime.ClientResponse, consumer runtime.Consumer) (interface{}, error) {
+	switch response.Code() {
+	case 200:
+		result := NewArkServiceSendTreeSignaturesOK()
+		if err := result.readResponse(response, consumer, o.formats); err != nil {
+			return nil, err
+		}
+		return result, nil
+	default:
+		result := NewArkServiceSendTreeSignaturesDefault(response.Code())
+		if err := result.readResponse(response, consumer, o.formats); err != nil {
+			return nil, err
+		}
+		if response.Code()/100 == 2 {
+			return result, nil
+		}
+		return nil, result
+	}
+}
+
+// NewArkServiceSendTreeSignaturesOK creates a ArkServiceSendTreeSignaturesOK with default headers values
+func NewArkServiceSendTreeSignaturesOK() *ArkServiceSendTreeSignaturesOK {
+	return &ArkServiceSendTreeSignaturesOK{}
+}
+
+/*
+ArkServiceSendTreeSignaturesOK describes a response with status code 200, with default header values.
+
+A successful response.
+*/
+type ArkServiceSendTreeSignaturesOK struct {
+	Payload models.V1SendTreeSignaturesResponse
+}
+
+// IsSuccess returns true when this ark service send tree signatures o k response has a 2xx status code
+func (o *ArkServiceSendTreeSignaturesOK) IsSuccess() bool {
+	return true
+}
+
+// IsRedirect returns true when this ark service send tree signatures o k response has a 3xx status code
+func (o *ArkServiceSendTreeSignaturesOK) IsRedirect() bool {
+	return false
+}
+
+// IsClientError returns true when this ark service send tree signatures o k response has a 4xx status code
+func (o *ArkServiceSendTreeSignaturesOK) IsClientError() bool {
+	return false
+}
+
+// IsServerError returns true when this ark service send tree signatures o k response has a 5xx status code
+func (o *ArkServiceSendTreeSignaturesOK) IsServerError() bool {
+	return false
+}
+
+// IsCode returns true when this ark service send tree signatures o k response a status code equal to that given
+func (o *ArkServiceSendTreeSignaturesOK) IsCode(code int) bool {
+	return code == 200
+}
+
+// Code gets the status code for the ark service send tree signatures o k response
+func (o *ArkServiceSendTreeSignaturesOK) Code() int {
+	return 200
+}
+
+func (o *ArkServiceSendTreeSignaturesOK) Error() string {
+	payload, _ := json.Marshal(o.Payload)
+	return fmt.Sprintf("[POST /v1/payment/tree/signatures][%d] arkServiceSendTreeSignaturesOK %s", 200, payload)
+}
+
+func (o *ArkServiceSendTreeSignaturesOK) String() string {
+	payload, _ := json.Marshal(o.Payload)
+	return fmt.Sprintf("[POST /v1/payment/tree/signatures][%d] arkServiceSendTreeSignaturesOK %s", 200, payload)
+}
+
+func (o *ArkServiceSendTreeSignaturesOK) GetPayload() models.V1SendTreeSignaturesResponse {
+	return o.Payload
+}
+
+func (o *ArkServiceSendTreeSignaturesOK) readResponse(response runtime.ClientResponse, consumer runtime.Consumer, formats strfmt.Registry) error {
+
+	// response payload
+	if err := consumer.Consume(response.Body(), &o.Payload); err != nil && err != io.EOF {
+		return err
+	}
+
+	return nil
+}
+
+// NewArkServiceSendTreeSignaturesDefault creates a ArkServiceSendTreeSignaturesDefault with default headers values
+func NewArkServiceSendTreeSignaturesDefault(code int) *ArkServiceSendTreeSignaturesDefault {
+	return &ArkServiceSendTreeSignaturesDefault{
+		_statusCode: code,
+	}
+}
+
+/*
+ArkServiceSendTreeSignaturesDefault describes a response with status code -1, with default header values.
+
+An unexpected error response.
+*/
+type ArkServiceSendTreeSignaturesDefault struct {
+	_statusCode int
+
+	Payload *models.RPCStatus
+}
+
+// IsSuccess returns true when this ark service send tree signatures default response has a 2xx status code
+func (o *ArkServiceSendTreeSignaturesDefault) IsSuccess() bool {
+	return o._statusCode/100 == 2
+}
+
+// IsRedirect returns true when this ark service send tree signatures default response has a 3xx status code
+func (o *ArkServiceSendTreeSignaturesDefault) IsRedirect() bool {
+	return o._statusCode/100 == 3
+}
+
+// IsClientError returns true when this ark service send tree signatures default response has a 4xx status code
+func (o *ArkServiceSendTreeSignaturesDefault) IsClientError() bool {
+	return o._statusCode/100 == 4
+}
+
+// IsServerError returns true when this ark service send tree signatures default response has a 5xx status code
+func (o *ArkServiceSendTreeSignaturesDefault) IsServerError() bool {
+	return o._statusCode/100 == 5
+}
+
+// IsCode returns true when this ark service send tree signatures default response a status code equal to that given
+func (o *ArkServiceSendTreeSignaturesDefault) IsCode(code int) bool {
+	return o._statusCode == code
+}
+
+// Code gets the status code for the ark service send tree signatures default response
+func (o *ArkServiceSendTreeSignaturesDefault) Code() int {
+	return o._statusCode
+}
+
+func (o *ArkServiceSendTreeSignaturesDefault) Error() string {
+	payload, _ := json.Marshal(o.Payload)
+	return fmt.Sprintf("[POST /v1/payment/tree/signatures][%d] ArkService_SendTreeSignatures default %s", o._statusCode, payload)
+}
+
+func (o *ArkServiceSendTreeSignaturesDefault) String() string {
+	payload, _ := json.Marshal(o.Payload)
+	return fmt.Sprintf("[POST /v1/payment/tree/signatures][%d] ArkService_SendTreeSignatures default %s", o._statusCode, payload)
+}
+
+func (o *ArkServiceSendTreeSignaturesDefault) GetPayload() *models.RPCStatus {
+	return o.Payload
+}
+
+func (o *ArkServiceSendTreeSignaturesDefault) readResponse(response runtime.ClientResponse, consumer runtime.Consumer, formats strfmt.Registry) error {
+
+	o.Payload = new(models.RPCStatus)
+
+	// response payload
+	if err := consumer.Consume(response.Body(), o.Payload); err != nil && err != io.EOF {
+		return err
+	}
+
+	return nil
+}

pkg/client-sdk/client/rest/service/models/v1_get_event_stream_response.go

@@ -21,11 +21,17 @@ type V1GetEventStreamResponse struct {
 	// round failed
 	RoundFailed *V1RoundFailed `json:"roundFailed,omitempty"`
 
-	// TODO: BTC add "signTree" event
+	// round finalization
 	RoundFinalization *V1RoundFinalizationEvent `json:"roundFinalization,omitempty"`
 
 	// round finalized
 	RoundFinalized *V1RoundFinalizedEvent `json:"roundFinalized,omitempty"`
+
+	// round signing
+	RoundSigning *V1RoundSigningEvent `json:"roundSigning,omitempty"`
+
+	// round signing nonces generated
+	RoundSigningNoncesGenerated *V1RoundSigningNoncesGeneratedEvent `json:"roundSigningNoncesGenerated,omitempty"`
 }
 
 // Validate validates this v1 get event stream response
@@ -44,6 +50,14 @@ func (m *V1GetEventStreamResponse) Validate(formats strfmt.Registry) error {
 		res = append(res, err)
 	}
 
+	if err := m.validateRoundSigning(formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.validateRoundSigningNoncesGenerated(formats); err != nil {
+		res = append(res, err)
+	}
+
 	if len(res) > 0 {
 		return errors.CompositeValidationError(res...)
 	}
@@ -107,6 +121,44 @@ func (m *V1GetEventStreamResponse) validateRoundFinalized(formats strfmt.Registr
 	return nil
 }
 
+func (m *V1GetEventStreamResponse) validateRoundSigning(formats strfmt.Registry) error {
+	if swag.IsZero(m.RoundSigning) { // not required
+		return nil
+	}
+
+	if m.RoundSigning != nil {
+		if err := m.RoundSigning.Validate(formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundSigning")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundSigning")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1GetEventStreamResponse) validateRoundSigningNoncesGenerated(formats strfmt.Registry) error {
+	if swag.IsZero(m.RoundSigningNoncesGenerated) { // not required
+		return nil
+	}
+
+	if m.RoundSigningNoncesGenerated != nil {
+		if err := m.RoundSigningNoncesGenerated.Validate(formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundSigningNoncesGenerated")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundSigningNoncesGenerated")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
 // ContextValidate validate this v1 get event stream response based on the context it is used
 func (m *V1GetEventStreamResponse) ContextValidate(ctx context.Context, formats strfmt.Registry) error {
 	var res []error
@@ -123,6 +175,14 @@ func (m *V1GetEventStreamResponse) ContextValidate(ctx context.Context, formats
 		res = append(res, err)
 	}
 
+	if err := m.contextValidateRoundSigning(ctx, formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.contextValidateRoundSigningNoncesGenerated(ctx, formats); err != nil {
+		res = append(res, err)
+	}
+
 	if len(res) > 0 {
 		return errors.CompositeValidationError(res...)
 	}
@@ -192,6 +252,48 @@ func (m *V1GetEventStreamResponse) contextValidateRoundFinalized(ctx context.Con
 	return nil
 }
 
+func (m *V1GetEventStreamResponse) contextValidateRoundSigning(ctx context.Context, formats strfmt.Registry) error {
+
+	if m.RoundSigning != nil {
+
+		if swag.IsZero(m.RoundSigning) { // not required
+			return nil
+		}
+
+		if err := m.RoundSigning.ContextValidate(ctx, formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundSigning")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundSigning")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1GetEventStreamResponse) contextValidateRoundSigningNoncesGenerated(ctx context.Context, formats strfmt.Registry) error {
+
+	if m.RoundSigningNoncesGenerated != nil {
+
+		if swag.IsZero(m.RoundSigningNoncesGenerated) { // not required
+			return nil
+		}
+
+		if err := m.RoundSigningNoncesGenerated.ContextValidate(ctx, formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundSigningNoncesGenerated")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundSigningNoncesGenerated")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
 // MarshalBinary interface implementation
 func (m *V1GetEventStreamResponse) MarshalBinary() ([]byte, error) {
 	if m == nil {

pkg/client-sdk/client/rest/service/models/v1_ping_response.go

@@ -18,18 +18,43 @@ import (
 // swagger:model v1PingResponse
 type V1PingResponse struct {
 
-	// event
+	// round failed
-	Event *V1RoundFinalizationEvent `json:"event,omitempty"`
+	RoundFailed *V1RoundFailed `json:"roundFailed,omitempty"`
 
-	// forfeit txs
+	// round finalization
-	ForfeitTxs []string `json:"forfeitTxs"`
+	RoundFinalization *V1RoundFinalizationEvent `json:"roundFinalization,omitempty"`
+
+	// round finalized
+	RoundFinalized *V1RoundFinalizedEvent `json:"roundFinalized,omitempty"`
+
+	// round signing
+	RoundSigning *V1RoundSigningEvent `json:"roundSigning,omitempty"`
+
+	// round signing nonces generated
+	RoundSigningNoncesGenerated *V1RoundSigningNoncesGeneratedEvent `json:"roundSigningNoncesGenerated,omitempty"`
 }
 
 // Validate validates this v1 ping response
 func (m *V1PingResponse) Validate(formats strfmt.Registry) error {
 	var res []error
 
-	if err := m.validateEvent(formats); err != nil {
+	if err := m.validateRoundFailed(formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.validateRoundFinalization(formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.validateRoundFinalized(formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.validateRoundSigning(formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.validateRoundSigningNoncesGenerated(formats); err != nil {
 		res = append(res, err)
 	}
 
@@ -39,17 +64,93 @@ func (m *V1PingResponse) Validate(formats strfmt.Registry) error {
 	return nil
 }
 
-func (m *V1PingResponse) validateEvent(formats strfmt.Registry) error {
+func (m *V1PingResponse) validateRoundFailed(formats strfmt.Registry) error {
-	if swag.IsZero(m.Event) { // not required
+	if swag.IsZero(m.RoundFailed) { // not required
 		return nil
 	}
 
-	if m.Event != nil {
+	if m.RoundFailed != nil {
-		if err := m.Event.Validate(formats); err != nil {
+		if err := m.RoundFailed.Validate(formats); err != nil {
 			if ve, ok := err.(*errors.Validation); ok {
-				return ve.ValidateName("event")
+				return ve.ValidateName("roundFailed")
 			} else if ce, ok := err.(*errors.CompositeError); ok {
-				return ce.ValidateName("event")
+				return ce.ValidateName("roundFailed")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1PingResponse) validateRoundFinalization(formats strfmt.Registry) error {
+	if swag.IsZero(m.RoundFinalization) { // not required
+		return nil
+	}
+
+	if m.RoundFinalization != nil {
+		if err := m.RoundFinalization.Validate(formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundFinalization")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundFinalization")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1PingResponse) validateRoundFinalized(formats strfmt.Registry) error {
+	if swag.IsZero(m.RoundFinalized) { // not required
+		return nil
+	}
+
+	if m.RoundFinalized != nil {
+		if err := m.RoundFinalized.Validate(formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundFinalized")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundFinalized")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1PingResponse) validateRoundSigning(formats strfmt.Registry) error {
+	if swag.IsZero(m.RoundSigning) { // not required
+		return nil
+	}
+
+	if m.RoundSigning != nil {
+		if err := m.RoundSigning.Validate(formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundSigning")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundSigning")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1PingResponse) validateRoundSigningNoncesGenerated(formats strfmt.Registry) error {
+	if swag.IsZero(m.RoundSigningNoncesGenerated) { // not required
+		return nil
+	}
+
+	if m.RoundSigningNoncesGenerated != nil {
+		if err := m.RoundSigningNoncesGenerated.Validate(formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundSigningNoncesGenerated")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundSigningNoncesGenerated")
 			}
 			return err
 		}
@@ -62,7 +163,23 @@ func (m *V1PingResponse) validateEvent(formats strfmt.Registry) error {
 func (m *V1PingResponse) ContextValidate(ctx context.Context, formats strfmt.Registry) error {
 	var res []error
 
-	if err := m.contextValidateEvent(ctx, formats); err != nil {
+	if err := m.contextValidateRoundFailed(ctx, formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.contextValidateRoundFinalization(ctx, formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.contextValidateRoundFinalized(ctx, formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.contextValidateRoundSigning(ctx, formats); err != nil {
+		res = append(res, err)
+	}
+
+	if err := m.contextValidateRoundSigningNoncesGenerated(ctx, formats); err != nil {
 		res = append(res, err)
 	}
 
@@ -72,19 +189,103 @@ func (m *V1PingResponse) ContextValidate(ctx context.Context, formats strfmt.Reg
 	return nil
 }
 
-func (m *V1PingResponse) contextValidateEvent(ctx context.Context, formats strfmt.Registry) error {
+func (m *V1PingResponse) contextValidateRoundFailed(ctx context.Context, formats strfmt.Registry) error {
 
-	if m.Event != nil {
+	if m.RoundFailed != nil {
 
-		if swag.IsZero(m.Event) { // not required
+		if swag.IsZero(m.RoundFailed) { // not required
 			return nil
 		}
 
-		if err := m.Event.ContextValidate(ctx, formats); err != nil {
+		if err := m.RoundFailed.ContextValidate(ctx, formats); err != nil {
 			if ve, ok := err.(*errors.Validation); ok {
-				return ve.ValidateName("event")
+				return ve.ValidateName("roundFailed")
 			} else if ce, ok := err.(*errors.CompositeError); ok {
-				return ce.ValidateName("event")
+				return ce.ValidateName("roundFailed")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1PingResponse) contextValidateRoundFinalization(ctx context.Context, formats strfmt.Registry) error {
+
+	if m.RoundFinalization != nil {
+
+		if swag.IsZero(m.RoundFinalization) { // not required
+			return nil
+		}
+
+		if err := m.RoundFinalization.ContextValidate(ctx, formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundFinalization")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundFinalization")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1PingResponse) contextValidateRoundFinalized(ctx context.Context, formats strfmt.Registry) error {
+
+	if m.RoundFinalized != nil {
+
+		if swag.IsZero(m.RoundFinalized) { // not required
+			return nil
+		}
+
+		if err := m.RoundFinalized.ContextValidate(ctx, formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundFinalized")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundFinalized")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1PingResponse) contextValidateRoundSigning(ctx context.Context, formats strfmt.Registry) error {
+
+	if m.RoundSigning != nil {
+
+		if swag.IsZero(m.RoundSigning) { // not required
+			return nil
+		}
+
+		if err := m.RoundSigning.ContextValidate(ctx, formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundSigning")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundSigning")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *V1PingResponse) contextValidateRoundSigningNoncesGenerated(ctx context.Context, formats strfmt.Registry) error {
+
+	if m.RoundSigningNoncesGenerated != nil {
+
+		if swag.IsZero(m.RoundSigningNoncesGenerated) { // not required
+			return nil
+		}
+
+		if err := m.RoundSigningNoncesGenerated.ContextValidate(ctx, formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("roundSigningNoncesGenerated")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("roundSigningNoncesGenerated")
 			}
 			return err
 		}

pkg/client-sdk/client/rest/service/models/v1_register_payment_request.go

@@ -19,6 +19,9 @@ import (
 // swagger:model v1RegisterPaymentRequest
 type V1RegisterPaymentRequest struct {
 
+	// ephemeral pubkey
+	EphemeralPubkey string `json:"ephemeralPubkey,omitempty"`
+
 	// inputs
 	Inputs []*V1Input `json:"inputs"`
 }

pkg/client-sdk/client/rest/service/models/v1_round_signing_event.go

@@ -0,0 +1,115 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package models
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+import (
+	"context"
+
+	"github.com/go-openapi/errors"
+	"github.com/go-openapi/strfmt"
+	"github.com/go-openapi/swag"
+)
+
+// V1RoundSigningEvent v1 round signing event
+//
+// swagger:model v1RoundSigningEvent
+type V1RoundSigningEvent struct {
+
+	// cosigners pubkeys
+	CosignersPubkeys []string `json:"cosignersPubkeys"`
+
+	// id
+	ID string `json:"id,omitempty"`
+
+	// unsigned tree
+	UnsignedTree *V1Tree `json:"unsignedTree,omitempty"`
+}
+
+// Validate validates this v1 round signing event
+func (m *V1RoundSigningEvent) Validate(formats strfmt.Registry) error {
+	var res []error
+
+	if err := m.validateUnsignedTree(formats); err != nil {
+		res = append(res, err)
+	}
+
+	if len(res) > 0 {
+		return errors.CompositeValidationError(res...)
+	}
+	return nil
+}
+
+func (m *V1RoundSigningEvent) validateUnsignedTree(formats strfmt.Registry) error {
+	if swag.IsZero(m.UnsignedTree) { // not required
+		return nil
+	}
+
+	if m.UnsignedTree != nil {
+		if err := m.UnsignedTree.Validate(formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("unsignedTree")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("unsignedTree")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+// ContextValidate validate this v1 round signing event based on the context it is used
+func (m *V1RoundSigningEvent) ContextValidate(ctx context.Context, formats strfmt.Registry) error {
+	var res []error
+
+	if err := m.contextValidateUnsignedTree(ctx, formats); err != nil {
+		res = append(res, err)
+	}
+
+	if len(res) > 0 {
+		return errors.CompositeValidationError(res...)
+	}
+	return nil
+}
+
+func (m *V1RoundSigningEvent) contextValidateUnsignedTree(ctx context.Context, formats strfmt.Registry) error {
+
+	if m.UnsignedTree != nil {
+
+		if swag.IsZero(m.UnsignedTree) { // not required
+			return nil
+		}
+
+		if err := m.UnsignedTree.ContextValidate(ctx, formats); err != nil {
+			if ve, ok := err.(*errors.Validation); ok {
+				return ve.ValidateName("unsignedTree")
+			} else if ce, ok := err.(*errors.CompositeError); ok {
+				return ce.ValidateName("unsignedTree")
+			}
+			return err
+		}
+	}
+
+	return nil
+}
+
+// MarshalBinary interface implementation
+func (m *V1RoundSigningEvent) MarshalBinary() ([]byte, error) {
+	if m == nil {
+		return nil, nil
+	}
+	return swag.WriteJSON(m)
+}
+
+// UnmarshalBinary interface implementation
+func (m *V1RoundSigningEvent) UnmarshalBinary(b []byte) error {
+	var res V1RoundSigningEvent
+	if err := swag.ReadJSON(b, &res); err != nil {
+		return err
+	}
+	*m = res
+	return nil
+}

pkg/client-sdk/client/rest/service/models/v1_round_signing_nonces_generated_event.go

@@ -0,0 +1,53 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package models
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+import (
+	"context"
+
+	"github.com/go-openapi/strfmt"
+	"github.com/go-openapi/swag"
+)
+
+// V1RoundSigningNoncesGeneratedEvent v1 round signing nonces generated event
+//
+// swagger:model v1RoundSigningNoncesGeneratedEvent
+type V1RoundSigningNoncesGeneratedEvent struct {
+
+	// id
+	ID string `json:"id,omitempty"`
+
+	// tree nonces
+	TreeNonces string `json:"treeNonces,omitempty"`
+}
+
+// Validate validates this v1 round signing nonces generated event
+func (m *V1RoundSigningNoncesGeneratedEvent) Validate(formats strfmt.Registry) error {
+	return nil
+}
+
+// ContextValidate validates this v1 round signing nonces generated event based on context it is used
+func (m *V1RoundSigningNoncesGeneratedEvent) ContextValidate(ctx context.Context, formats strfmt.Registry) error {
+	return nil
+}
+
+// MarshalBinary interface implementation
+func (m *V1RoundSigningNoncesGeneratedEvent) MarshalBinary() ([]byte, error) {
+	if m == nil {
+		return nil, nil
+	}
+	return swag.WriteJSON(m)
+}
+
+// UnmarshalBinary interface implementation
+func (m *V1RoundSigningNoncesGeneratedEvent) UnmarshalBinary(b []byte) error {
+	var res V1RoundSigningNoncesGeneratedEvent
+	if err := swag.ReadJSON(b, &res); err != nil {
+		return err
+	}
+	*m = res
+	return nil
+}

pkg/client-sdk/client/rest/service/models/v1_send_tree_nonces_request.go

@@ -0,0 +1,56 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package models
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+import (
+	"context"
+
+	"github.com/go-openapi/strfmt"
+	"github.com/go-openapi/swag"
+)
+
+// V1SendTreeNoncesRequest v1 send tree nonces request
+//
+// swagger:model v1SendTreeNoncesRequest
+type V1SendTreeNoncesRequest struct {
+
+	// public key
+	PublicKey string `json:"publicKey,omitempty"`
+
+	// round Id
+	RoundID string `json:"roundId,omitempty"`
+
+	// tree nonces
+	TreeNonces string `json:"treeNonces,omitempty"`
+}
+
+// Validate validates this v1 send tree nonces request
+func (m *V1SendTreeNoncesRequest) Validate(formats strfmt.Registry) error {
+	return nil
+}
+
+// ContextValidate validates this v1 send tree nonces request based on context it is used
+func (m *V1SendTreeNoncesRequest) ContextValidate(ctx context.Context, formats strfmt.Registry) error {
+	return nil
+}
+
+// MarshalBinary interface implementation
+func (m *V1SendTreeNoncesRequest) MarshalBinary() ([]byte, error) {
+	if m == nil {
+		return nil, nil
+	}
+	return swag.WriteJSON(m)
+}
+
+// UnmarshalBinary interface implementation
+func (m *V1SendTreeNoncesRequest) UnmarshalBinary(b []byte) error {
+	var res V1SendTreeNoncesRequest
+	if err := swag.ReadJSON(b, &res); err != nil {
+		return err
+	}
+	*m = res
+	return nil
+}

pkg/client-sdk/client/rest/service/models/v1_send_tree_nonces_response.go

@@ -0,0 +1,11 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package models
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+// V1SendTreeNoncesResponse v1 send tree nonces response
+//
+// swagger:model v1SendTreeNoncesResponse
+type V1SendTreeNoncesResponse interface{}

pkg/client-sdk/client/rest/service/models/v1_send_tree_signatures_request.go

@@ -0,0 +1,56 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package models
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+import (
+	"context"
+
+	"github.com/go-openapi/strfmt"
+	"github.com/go-openapi/swag"
+)
+
+// V1SendTreeSignaturesRequest v1 send tree signatures request
+//
+// swagger:model v1SendTreeSignaturesRequest
+type V1SendTreeSignaturesRequest struct {
+
+	// public key
+	PublicKey string `json:"publicKey,omitempty"`
+
+	// round Id
+	RoundID string `json:"roundId,omitempty"`
+
+	// tree signatures
+	TreeSignatures string `json:"treeSignatures,omitempty"`
+}
+
+// Validate validates this v1 send tree signatures request
+func (m *V1SendTreeSignaturesRequest) Validate(formats strfmt.Registry) error {
+	return nil
+}
+
+// ContextValidate validates this v1 send tree signatures request based on context it is used
+func (m *V1SendTreeSignaturesRequest) ContextValidate(ctx context.Context, formats strfmt.Registry) error {
+	return nil
+}
+
+// MarshalBinary interface implementation
+func (m *V1SendTreeSignaturesRequest) MarshalBinary() ([]byte, error) {
+	if m == nil {
+		return nil, nil
+	}
+	return swag.WriteJSON(m)
+}
+
+// UnmarshalBinary interface implementation
+func (m *V1SendTreeSignaturesRequest) UnmarshalBinary(b []byte) error {
+	var res V1SendTreeSignaturesRequest
+	if err := swag.ReadJSON(b, &res); err != nil {
+		return err
+	}
+	*m = res
+	return nil
+}

pkg/client-sdk/client/rest/service/models/v1_send_tree_signatures_response.go

@@ -0,0 +1,11 @@
+// Code generated by go-swagger; DO NOT EDIT.
+
+package models
+
+// This file was generated by the swagger tool.
+// Editing this file might prove futile when you re-run the swagger generate command
+
+// V1SendTreeSignaturesResponse v1 send tree signatures response
+//
+// swagger:model v1SendTreeSignaturesResponse
+type V1SendTreeSignaturesResponse interface{}

pkg/client-sdk/covenant_client.go

@@ -528,7 +528,7 @@ func (a *covenantArkClient) CollaborativeRedeem(
 		})
 	}
 
-	paymentID, err := a.client.RegisterPayment(ctx, inputs)
+	paymentID, err := a.client.RegisterPayment(ctx, inputs, "") // ephemeralPublicKey is not required for covenant
 	if err != nil {
 		return "", err
 	}
@@ -796,7 +796,7 @@ func (a *covenantArkClient) sendOffchain(
 	}
 
 	paymentID, err := a.client.RegisterPayment(
-		ctx, inputs,
+		ctx, inputs, "", // ephemeralPublicKey is not required for covenant
 	)
 	if err != nil {
 		return "", err

pkg/client-sdk/covenantless_client.go

@@ -262,7 +262,11 @@ func (a *covenantlessArkClient) Onboard(
 		return "", err
 	}
 
-	if err := signer.SetKeys(cosigners, aggregatedNonces); err != nil {
+	if err := signer.SetKeys(cosigners); err != nil {
+		return "", err
+	}
+
+	if err := signer.SetAggregatedNonces(aggregatedNonces); err != nil {
 		return "", err
 	}
 
@@ -608,7 +612,16 @@ func (a *covenantlessArkClient) CollaborativeRedeem(
 		})
 	}
 
-	paymentID, err := a.client.RegisterPayment(ctx, inputs)
+	roundEphemeralKey, err := secp256k1.GeneratePrivateKey()
+	if err != nil {
+		return "", err
+	}
+
+	paymentID, err := a.client.RegisterPayment(
+		ctx,
+		inputs,
+		hex.EncodeToString(roundEphemeralKey.PubKey().SerializeCompressed()),
+	)
 	if err != nil {
 		return "", err
 	}
@@ -618,7 +631,7 @@ func (a *covenantlessArkClient) CollaborativeRedeem(
 	}
 
 	poolTxID, err := a.handleRoundStream(
-		ctx, paymentID, selectedCoins, receivers,
+		ctx, paymentID, selectedCoins, receivers, roundEphemeralKey,
 	)
 	if err != nil {
 		return "", err
@@ -990,8 +1003,13 @@ func (a *covenantlessArkClient) sendOffchain(
 		})
 	}
 
+	roundEphemeralKey, err := secp256k1.GeneratePrivateKey()
+	if err != nil {
+		return "", err
+	}
+
 	paymentID, err := a.client.RegisterPayment(
-		ctx, inputs,
+		ctx, inputs, hex.EncodeToString(roundEphemeralKey.PubKey().SerializeCompressed()),
 	)
 	if err != nil {
 		return "", err
@@ -1006,7 +1024,7 @@ func (a *covenantlessArkClient) sendOffchain(
 	log.Infof("payment registered with id: %s", paymentID)
 
 	poolTxID, err := a.handleRoundStream(
-		ctx, paymentID, selectedCoins, receiversOutput,
+		ctx, paymentID, selectedCoins, receiversOutput, roundEphemeralKey,
 	)
 	if err != nil {
 		return "", err
@@ -1144,7 +1162,10 @@ func (a *covenantlessArkClient) addVtxoInput(
 
 func (a *covenantlessArkClient) handleRoundStream(
 	ctx context.Context,
-	paymentID string, vtxosToSign []client.Vtxo, receivers []client.Output,
+	paymentID string,
+	vtxosToSign []client.Vtxo,
+	receivers []client.Output,
+	roundEphemeralKey *secp256k1.PrivateKey,
 ) (string, error) {
 	eventsCh, err := a.client.GetEventStream(ctx, paymentID)
 	if err != nil {
@@ -1158,6 +1179,8 @@ func (a *covenantlessArkClient) handleRoundStream(
 
 	defer pingStop()
 
+	var signerSession bitcointree.SignerSession
+
 	for {
 		select {
 		case <-ctx.Done():
@@ -1172,6 +1195,25 @@ func (a *covenantlessArkClient) handleRoundStream(
 				return event.(client.RoundFinalizedEvent).Txid, nil
 			case client.RoundFailedEvent:
 				return "", fmt.Errorf("round failed: %s", event.(client.RoundFailedEvent).Reason)
+			case client.RoundSigningStartedEvent:
+				pingStop()
+				log.Info("a round signing started")
+				signerSession, err = a.handleRoundSigningStarted(
+					ctx, roundEphemeralKey, event.(client.RoundSigningStartedEvent),
+				)
+				if err != nil {
+					return "", err
+				}
+				continue
+			case client.RoundSigningNoncesGeneratedEvent:
+				pingStop()
+				log.Info("round combined nonces generated")
+				if err := a.handleRoundSigningNoncesGenerated(
+					ctx, event.(client.RoundSigningNoncesGeneratedEvent), roundEphemeralKey, signerSession,
+				); err != nil {
+					return "", err
+				}
+				continue
 			case client.RoundFinalizationEvent:
 				pingStop()
 				log.Info("a round finalization started")
@@ -1200,6 +1242,73 @@ func (a *covenantlessArkClient) handleRoundStream(
 	}
 }
 
+func (a *covenantlessArkClient) handleRoundSigningStarted(
+	ctx context.Context, ephemeralKey *secp256k1.PrivateKey, event client.RoundSigningStartedEvent,
+) (signerSession bitcointree.SignerSession, err error) {
+	sweepClosure := bitcointree.CSVSigClosure{
+		Pubkey:  a.AspPubkey,
+		Seconds: uint(a.RoundLifetime),
+	}
+
+	sweepTapLeaf, err := sweepClosure.Leaf()
+	if err != nil {
+		return
+	}
+
+	sweepTapTree := txscript.AssembleTaprootScriptTree(*sweepTapLeaf)
+	root := sweepTapTree.RootNode.TapHash()
+
+	signerSession = bitcointree.NewTreeSignerSession(
+		ephemeralKey, event.UnsignedTree, int64(a.MinRelayFee), root.CloneBytes(),
+	)
+
+	if err = signerSession.SetKeys(event.CosignersPublicKeys); err != nil {
+		return
+	}
+
+	nonces, err := signerSession.GetNonces()
+	if err != nil {
+		return
+	}
+
+	myPubKey := hex.EncodeToString(ephemeralKey.PubKey().SerializeCompressed())
+
+	err = a.arkClient.client.SendTreeNonces(ctx, event.ID, myPubKey, nonces)
+
+	return
+}
+
+func (a *covenantlessArkClient) handleRoundSigningNoncesGenerated(
+	ctx context.Context,
+	event client.RoundSigningNoncesGeneratedEvent,
+	ephemeralKey *secp256k1.PrivateKey,
+	signerSession bitcointree.SignerSession,
+) error {
+	if signerSession == nil {
+		return fmt.Errorf("tree signer session not set")
+	}
+
+	if err := signerSession.SetAggregatedNonces(event.Nonces); err != nil {
+		return err
+	}
+
+	sigs, err := signerSession.Sign()
+	if err != nil {
+		return err
+	}
+
+	if err := a.arkClient.client.SendTreeSignatures(
+		ctx,
+		event.ID,
+		hex.EncodeToString(ephemeralKey.PubKey().SerializeCompressed()),
+		sigs,
+	); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func (a *covenantlessArkClient) handleRoundFinalization(
 	ctx context.Context, event client.RoundFinalizationEvent,
 	vtxos []client.Vtxo, receivers []client.Output,
@@ -1619,7 +1728,16 @@ func (a *covenantlessArkClient) selfTransferAllPendingPayments(
 
 	outputs := []client.Output{myself}
 
-	paymentID, err := a.client.RegisterPayment(ctx, inputs)
+	roundEphemeralKey, err := secp256k1.GeneratePrivateKey()
+	if err != nil {
+		return "", err
+	}
+
+	paymentID, err := a.client.RegisterPayment(
+		ctx,
+		inputs,
+		hex.EncodeToString(roundEphemeralKey.PubKey().SerializeCompressed()),
+	)
 	if err != nil {
 		return "", err
 	}
@@ -1629,7 +1747,7 @@ func (a *covenantlessArkClient) selfTransferAllPendingPayments(
 	}
 
 	roundTxid, err := a.handleRoundStream(
-		ctx, paymentID, pendingVtxos, outputs,
+		ctx, paymentID, pendingVtxos, outputs, roundEphemeralKey,
 	)
 	if err != nil {
 		return "", err

server/internal/core/application/covenant.go

@@ -20,6 +20,10 @@ import (
 	"github.com/vulpemventures/go-elements/psetv2"
 )
 
+var (
+	ErrTreeSigningNotRequired = fmt.Errorf("tree signing is not required on this ark (covenant)")
+)
+
 type covenantService struct {
 	network             common.Network
 	pubkey              *secp256k1.PublicKey
@@ -40,6 +44,7 @@ type covenantService struct {
 	eventsCh     chan domain.RoundEvent
 	onboardingCh chan onboarding
 
+	lastEvent    domain.RoundEvent
 	currentRound *domain.Round
 }
 
@@ -66,7 +71,7 @@ func NewCovenantService(
 		network, pubkey,
 		roundLifetime, roundInterval, unilateralExitDelay, minRelayFee,
 		walletSvc, repoManager, builder, scanner, sweeper,
-		paymentRequests, forfeitTxs, eventsCh, onboardingCh, nil,
+		paymentRequests, forfeitTxs, eventsCh, onboardingCh, nil, nil,
 	}
 	repoManager.RegisterEventsHandler(
 		func(round *domain.Round) {
@@ -148,17 +153,17 @@ func (s *covenantService) ClaimVtxos(ctx context.Context, creds string, receiver
 	return s.paymentRequests.update(*payment)
 }
 
-func (s *covenantService) UpdatePaymentStatus(_ context.Context, id string) ([]string, *domain.Round, error) {
+func (s *covenantService) UpdatePaymentStatus(_ context.Context, id string) (domain.RoundEvent, error) {
 	err := s.paymentRequests.updatePingTimestamp(id)
 	if err != nil {
 		if _, ok := err.(errPaymentNotFound); ok {
-			return s.forfeitTxs.view(), s.currentRound, nil
+			return s.lastEvent, nil
 		}
 
-		return nil, nil, err
+		return nil, err
 	}
 
-	return nil, nil, nil
+	return s.lastEvent, nil
 }
 
 func (s *covenantService) CompleteAsyncPayment(ctx context.Context, redeemTx string, unconditionalForfeitTxs []string) error {
@@ -248,6 +253,24 @@ func (s *covenantService) Onboard(
 	return nil
 }
 
+func (s *covenantService) RegisterCosignerPubkey(ctx context.Context, paymentId string, _ string) error {
+	// if the user sends an ephemeral pubkey, something is going wrong client-side
+	// we should delete the associated payment
+	if err := s.paymentRequests.delete(paymentId); err != nil {
+		log.WithError(err).Warn("failed to delete payment")
+	}
+
+	return ErrTreeSigningNotRequired
+}
+
+func (s *covenantService) RegisterCosignerNonces(context.Context, string, *secp256k1.PublicKey, string) error {
+	return ErrTreeSigningNotRequired
+}
+
+func (s *covenantService) RegisterCosignerSignatures(context.Context, string, *secp256k1.PublicKey, string) error {
+	return ErrTreeSigningNotRequired
+}
+
 func (s *covenantService) start() {
 	s.startRound()
 }
@@ -256,6 +279,7 @@ func (s *covenantService) startRound() {
 	round := domain.NewRound(dustAmount)
 	//nolint:all
 	round.StartRegistration()
+	s.lastEvent = nil
 	s.currentRound = round
 
 	defer func() {
@@ -305,7 +329,7 @@ func (s *covenantService) startFinalization() {
 	if num > paymentsThreshold {
 		num = paymentsThreshold
 	}
-	payments := s.paymentRequests.pop(num)
+	payments, _ := s.paymentRequests.pop(num)
 	if _, err := round.RegisterPayments(payments); err != nil {
 		round.Fail(fmt.Errorf("failed to register payments: %s", err))
 		log.WithError(err).Warn("failed to register payments")
@@ -670,14 +694,17 @@ func (s *covenantService) propagateEvents(round *domain.Round) {
 	switch e := lastEvent.(type) {
 	case domain.RoundFinalizationStarted:
 		forfeitTxs := s.forfeitTxs.view()
-		s.eventsCh <- domain.RoundFinalizationStarted{
+		ev := domain.RoundFinalizationStarted{
 			Id:                 e.Id,
 			CongestionTree:     e.CongestionTree,
 			Connectors:         e.Connectors,
 			PoolTx:             e.PoolTx,
 			UnsignedForfeitTxs: forfeitTxs,
 		}
+		s.lastEvent = ev
+		s.eventsCh <- ev
 	case domain.RoundFinalized, domain.RoundFailed:
+		s.lastEvent = e
 		s.eventsCh <- e
 	}
 }

server/internal/core/application/covenantless.go

@@ -41,9 +41,11 @@ type covenantlessService struct {
 	eventsCh     chan domain.RoundEvent
 	onboardingCh chan onboarding
 
-	currentRound *domain.Round
+	// cached data for the current round
-
+	lastEvent           domain.RoundEvent
-	asyncPaymentsCache map[domain.VtxoKey]struct {
+	currentRound        *domain.Round
+	treeSigningSessions map[string]*musigSigningSession
+	asyncPaymentsCache  map[domain.VtxoKey]struct {
 		receivers []domain.Receiver
 		expireAt  int64
 	}
@@ -89,6 +91,7 @@ func NewCovenantlessService(
 		eventsCh:            eventsCh,
 		onboardingCh:        onboardingCh,
 		asyncPaymentsCache:  asyncPaymentsCache,
+		treeSigningSessions: make(map[string]*musigSigningSession),
 	}
 
 	repoManager.RegisterEventsHandler(
@@ -273,17 +276,17 @@ func (s *covenantlessService) ClaimVtxos(ctx context.Context, creds string, rece
 	return s.paymentRequests.update(*payment)
 }
 
-func (s *covenantlessService) UpdatePaymentStatus(_ context.Context, id string) ([]string, *domain.Round, error) {
+func (s *covenantlessService) UpdatePaymentStatus(_ context.Context, id string) (domain.RoundEvent, error) {
 	err := s.paymentRequests.updatePingTimestamp(id)
 	if err != nil {
 		if _, ok := err.(errPaymentNotFound); ok {
-			return s.forfeitTxs.view(), s.currentRound, nil
+			return s.lastEvent, nil
 		}
 
-		return nil, nil, err
+		return nil, err
 	}
 
-	return nil, nil, nil
+	return s.lastEvent, nil
 }
 
 func (s *covenantlessService) SignVtxos(ctx context.Context, forfeitTxs []string) error {
@@ -367,6 +370,78 @@ func (s *covenantlessService) Onboard(
 	return nil
 }
 
+func (s *covenantlessService) RegisterCosignerPubkey(ctx context.Context, paymentId string, pubkey string) error {
+	pubkeyBytes, err := hex.DecodeString(pubkey)
+	if err != nil {
+		return fmt.Errorf("failed to decode hex pubkey: %s", err)
+	}
+
+	ephemeralPublicKey, err := secp256k1.ParsePubKey(pubkeyBytes)
+	if err != nil {
+		return fmt.Errorf("failed to parse pubkey: %s", err)
+	}
+
+	return s.paymentRequests.pushEphemeralKey(paymentId, ephemeralPublicKey)
+}
+
+func (s *covenantlessService) RegisterCosignerNonces(
+	ctx context.Context, roundID string, pubkey *secp256k1.PublicKey, encodedNonces string,
+) error {
+	session, ok := s.treeSigningSessions[roundID]
+	if !ok {
+		return fmt.Errorf(`signing session not found for round "%s"`, roundID)
+	}
+
+	nonces, err := bitcointree.DecodeNonces(hex.NewDecoder(strings.NewReader(encodedNonces)))
+	if err != nil {
+		return fmt.Errorf("failed to decode nonces: %s", err)
+	}
+
+	session.lock.Lock()
+	defer session.lock.Unlock()
+
+	if _, ok := session.nonces[pubkey]; ok {
+		return nil // skip if we already have nonces for this pubkey
+	}
+
+	session.nonces[pubkey] = nonces
+
+	if len(session.nonces) == session.nbCosigners-1 { // exclude the ASP
+		session.nonceDoneC <- struct{}{}
+	}
+
+	return nil
+}
+
+func (s *covenantlessService) RegisterCosignerSignatures(
+	ctx context.Context, roundID string, pubkey *secp256k1.PublicKey, encodedSignatures string,
+) error {
+	session, ok := s.treeSigningSessions[roundID]
+	if !ok {
+		return fmt.Errorf(`signing session not found for round "%s"`, roundID)
+	}
+
+	signatures, err := bitcointree.DecodeSignatures(hex.NewDecoder(strings.NewReader(encodedSignatures)))
+	if err != nil {
+		return fmt.Errorf("failed to decode signatures: %s", err)
+	}
+
+	session.lock.Lock()
+	defer session.lock.Unlock()
+
+	if _, ok := session.signatures[pubkey]; ok {
+		return nil // skip if we already have signatures for this pubkey
+	}
+
+	session.signatures[pubkey] = signatures
+
+	if len(session.signatures) == session.nbCosigners-1 { // exclude the ASP
+		session.sigDoneC <- struct{}{}
+	}
+
+	return nil
+}
+
 func (s *covenantlessService) start() {
 	s.startRound()
 }
@@ -375,6 +450,7 @@ func (s *covenantlessService) startRound() {
 	round := domain.NewRound(dustAmount) // TODO dynamic dust amount?
 	//nolint:all
 	round.StartRegistration()
+	s.lastEvent = nil
 	s.currentRound = round
 
 	defer func() {
@@ -389,8 +465,12 @@ func (s *covenantlessService) startFinalization() {
 	ctx := context.Background()
 	round := s.currentRound
 
+	roundRemainingDuration := time.Duration(s.roundInterval/2-1) * time.Second
+	thirdOfRemainingDuration := time.Duration(roundRemainingDuration / 3)
+
 	var roundAborted bool
 	defer func() {
+		delete(s.treeSigningSessions, round.Id)
 		if roundAborted {
 			s.startRound()
 			return
@@ -404,7 +484,7 @@ func (s *covenantlessService) startFinalization() {
 			s.startRound()
 			return
 		}
-		time.Sleep(time.Duration((s.roundInterval/2)-1) * time.Second)
+		time.Sleep(thirdOfRemainingDuration)
 		s.finalizeRound()
 	}()
 
@@ -424,7 +504,14 @@ func (s *covenantlessService) startFinalization() {
 	if num > paymentsThreshold {
 		num = paymentsThreshold
 	}
-	payments := s.paymentRequests.pop(num)
+	payments, cosigners := s.paymentRequests.pop(num)
+	if len(payments) > len(cosigners) {
+		err := fmt.Errorf("missing ephemeral key for payments")
+		round.Fail(fmt.Errorf("round aborted: %s", err))
+		log.WithError(err).Debugf("round %s aborted", round.Id)
+		return
+	}
+
 	if _, err := round.RegisterPayments(payments); err != nil {
 		round.Fail(fmt.Errorf("failed to register payments: %s", err))
 		log.WithError(err).Warn("failed to register payments")
@@ -438,32 +525,16 @@ func (s *covenantlessService) startFinalization() {
 		return
 	}
 
-	cosigners := make([]*secp256k1.PrivateKey, 0)
+	ephemeralKey, err := secp256k1.GeneratePrivateKey()
-	cosignersPubKeys := make([]*secp256k1.PublicKey, 0, len(cosigners))
-	for range payments {
-		// TODO sender should provide the ephemeral *public* key
-		ephemeralKey, err := secp256k1.GeneratePrivateKey()
-		if err != nil {
-			round.Fail(fmt.Errorf("failed to generate ephemeral key: %s", err))
-			log.WithError(err).Warn("failed to generate ephemeral key")
-			return
-		}
-
-		cosigners = append(cosigners, ephemeralKey)
-		cosignersPubKeys = append(cosignersPubKeys, ephemeralKey.PubKey())
-	}
-
-	aspSigningKey, err := secp256k1.GeneratePrivateKey()
 	if err != nil {
-		round.Fail(fmt.Errorf("failed to generate asp signing key: %s", err))
+		round.Fail(fmt.Errorf("failed to generate ephemeral key: %s", err))
-		log.WithError(err).Warn("failed to generate asp signing key")
+		log.WithError(err).Warn("failed to generate ephemeral key")
 		return
 	}
 
-	cosigners = append(cosigners, aspSigningKey)
+	cosigners = append(cosigners, ephemeralKey.PubKey())
-	cosignersPubKeys = append(cosignersPubKeys, aspSigningKey.PubKey())
 
-	unsignedPoolTx, tree, connectorAddress, err := s.builder.BuildPoolTx(s.pubkey, payments, s.minRelayFee, sweptRounds, cosignersPubKeys...)
+	unsignedPoolTx, tree, connectorAddress, err := s.builder.BuildPoolTx(s.pubkey, payments, s.minRelayFee, sweptRounds, cosigners...)
 	if err != nil {
 		round.Fail(fmt.Errorf("failed to create pool tx: %s", err))
 		log.WithError(err).Warn("failed to create pool tx")
@@ -472,6 +543,16 @@ func (s *covenantlessService) startFinalization() {
 	log.Debugf("pool tx created for round %s", round.Id)
 
 	if len(tree) > 0 {
+		log.Debugf("signing congestion tree for round %s", round.Id)
+
+		signingSession := newMusigSigningSession(len(cosigners))
+		s.treeSigningSessions[round.Id] = signingSession
+
+		log.Debugf("signing session created for round %s", round.Id)
+
+		// send back the unsigned tree & all cosigners pubkeys
+		s.propagateRoundSigningStartedEvent(tree, cosigners)
+
 		sweepClosure := bitcointree.CSVSigClosure{
 			Pubkey:  s.pubkey,
 			Seconds: uint(s.roundLifetime),
@@ -485,37 +566,50 @@ func (s *covenantlessService) startFinalization() {
 		sweepTapTree := txscript.AssembleTaprootScriptTree(*sweepTapLeaf)
 		root := sweepTapTree.RootNode.TapHash()
 
-		coordinator, err := s.createTreeCoordinatorSession(tree, cosignersPubKeys, root)
+		coordinator, err := s.createTreeCoordinatorSession(tree, cosigners, root)
 		if err != nil {
 			round.Fail(fmt.Errorf("failed to create tree coordinator: %s", err))
 			log.WithError(err).Warn("failed to create tree coordinator")
 			return
 		}
 
-		signers := make([]bitcointree.SignerSession, 0)
+		aspSignerSession := bitcointree.NewTreeSignerSession(
+			ephemeralKey, tree, int64(s.minRelayFee), root.CloneBytes(),
+		)
 
-		for _, seckey := range cosigners {
+		nonces, err := aspSignerSession.GetNonces()
-			signer := bitcointree.NewTreeSignerSession(
+		if err != nil {
-				seckey, tree, int64(s.minRelayFee), root.CloneBytes(),
+			round.Fail(fmt.Errorf("failed to get nonces: %s", err))
-			)
+			log.WithError(err).Warn("failed to get nonces")
-
+			return
-			// TODO nonces should be sent by the sender
-			nonces, err := signer.GetNonces()
-			if err != nil {
-				round.Fail(fmt.Errorf("failed to get nonces: %s", err))
-				log.WithError(err).Warn("failed to get nonces")
-				return
-			}
-
-			if err := coordinator.AddNonce(seckey.PubKey(), nonces); err != nil {
-				round.Fail(fmt.Errorf("failed to add nonce: %s", err))
-				log.WithError(err).Warn("failed to add nonce")
-				return
-			}
-
-			signers = append(signers, signer)
 		}
 
+		if err := coordinator.AddNonce(ephemeralKey.PubKey(), nonces); err != nil {
+			round.Fail(fmt.Errorf("failed to add nonce: %s", err))
+			log.WithError(err).Warn("failed to add nonce")
+			return
+		}
+
+		noncesTimer := time.NewTimer(thirdOfRemainingDuration)
+
+		select {
+		case <-noncesTimer.C:
+			round.Fail(fmt.Errorf("musig2 signing session timed out (nonce collection)"))
+			log.Warn("musig2 signing session timed out (nonce collection)")
+			return
+		case <-signingSession.nonceDoneC:
+			noncesTimer.Stop()
+			for pubkey, nonce := range signingSession.nonces {
+				if err := coordinator.AddNonce(pubkey, nonce); err != nil {
+					round.Fail(fmt.Errorf("failed to add nonce: %s", err))
+					log.WithError(err).Warn("failed to add nonce")
+					return
+				}
+			}
+		}
+
+		log.Debugf("nonces collected for round %s", round.Id)
+
 		aggragatedNonces, err := coordinator.AggregateNonces()
 		if err != nil {
 			round.Fail(fmt.Errorf("failed to aggregate nonces: %s", err))
@@ -523,36 +617,69 @@ func (s *covenantlessService) startFinalization() {
 			return
 		}
 
-		// TODO aggragated nonces and public keys should be sent back to signer
+		log.Debugf("nonces aggregated for round %s", round.Id)
-		// TODO signing should be done client-side (except for the ASP)
-		for i, signer := range signers {
-			if err := signer.SetKeys(cosignersPubKeys, aggragatedNonces); err != nil {
-				round.Fail(fmt.Errorf("failed to set keys: %s", err))
-				log.WithError(err).Warn("failed to set keys")
-				return
-			}
 
-			sig, err := signer.Sign()
+		s.propagateRoundSigningNoncesGeneratedEvent(aggragatedNonces)
-			if err != nil {
-				round.Fail(fmt.Errorf("failed to sign: %s", err))
-				log.WithError(err).Warn("failed to sign")
-				return
-			}
 
-			if err := coordinator.AddSig(cosignersPubKeys[i], sig); err != nil {
+		if err := aspSignerSession.SetKeys(cosigners); err != nil {
-				round.Fail(fmt.Errorf("failed to add sig: %s", err))
+			round.Fail(fmt.Errorf("failed to set keys: %s", err))
-				log.WithError(err).Warn("failed to add sig")
+			log.WithError(err).Warn("failed to set keys")
-				return
+			return
-			}
 		}
 
-		signedTree, err := coordinator.SignTree()
+		if err := aspSignerSession.SetAggregatedNonces(aggragatedNonces); err != nil {
+			round.Fail(fmt.Errorf("failed to set aggregated nonces: %s", err))
+			log.WithError(err).Warn("failed to set aggregated nonces")
+			return
+		}
+
+		// sign the tree as ASP
+		aspTreeSigs, err := aspSignerSession.Sign()
 		if err != nil {
 			round.Fail(fmt.Errorf("failed to sign tree: %s", err))
 			log.WithError(err).Warn("failed to sign tree")
 			return
 		}
 
+		if err := coordinator.AddSig(ephemeralKey.PubKey(), aspTreeSigs); err != nil {
+			round.Fail(fmt.Errorf("failed to add signature: %s", err))
+			log.WithError(err).Warn("failed to add signature")
+			return
+		}
+
+		log.Debugf("ASP tree signed for round %s", round.Id)
+
+		signaturesTimer := time.NewTimer(thirdOfRemainingDuration)
+
+		log.Debugf("waiting for cosigners to sign the tree")
+
+		select {
+		case <-signaturesTimer.C:
+			round.Fail(fmt.Errorf("musig2 signing session timed out (signatures)"))
+			log.Warn("musig2 signing session timed out (signatures)")
+			return
+		case <-signingSession.sigDoneC:
+			signaturesTimer.Stop()
+			for pubkey, sig := range signingSession.signatures {
+				if err := coordinator.AddSig(pubkey, sig); err != nil {
+					round.Fail(fmt.Errorf("failed to add signature: %s", err))
+					log.WithError(err).Warn("failed to add signature")
+					return
+				}
+			}
+		}
+
+		log.Debugf("signatures collected for round %s", round.Id)
+
+		signedTree, err := coordinator.SignTree()
+		if err != nil {
+			round.Fail(fmt.Errorf("failed to aggragate tree signatures: %s", err))
+			log.WithError(err).Warn("failed aggragate tree signatures")
+			return
+		}
+
+		log.Debugf("congestion tree signed for round %s", round.Id)
+
 		tree = signedTree
 	}
 
@@ -578,6 +705,29 @@ func (s *covenantlessService) startFinalization() {
 	log.Debugf("started finalization stage for round: %s", round.Id)
 }
 
+func (s *covenantlessService) propagateRoundSigningStartedEvent(
+	unsignedCongestionTree tree.CongestionTree, cosigners []*secp256k1.PublicKey,
+) {
+	ev := RoundSigningStarted{
+		Id:               s.currentRound.Id,
+		UnsignedVtxoTree: unsignedCongestionTree,
+		Cosigners:        cosigners,
+	}
+
+	s.lastEvent = ev
+	s.eventsCh <- ev
+}
+
+func (s *covenantlessService) propagateRoundSigningNoncesGeneratedEvent(combinedNonces bitcointree.TreeNonces) {
+	ev := RoundSigningNoncesGenerated{
+		Id:     s.currentRound.Id,
+		Nonces: combinedNonces,
+	}
+
+	s.lastEvent = ev
+	s.eventsCh <- ev
+}
+
 func (s *covenantlessService) createTreeCoordinatorSession(
 	congestionTree tree.CongestionTree, cosigners []*secp256k1.PublicKey, root chainhash.Hash,
 ) (bitcointree.CoordinatorSession, error) {
@@ -900,14 +1050,17 @@ func (s *covenantlessService) propagateEvents(round *domain.Round) {
 	switch e := lastEvent.(type) {
 	case domain.RoundFinalizationStarted:
 		forfeitTxs := s.forfeitTxs.view()
-		s.eventsCh <- domain.RoundFinalizationStarted{
+		ev := domain.RoundFinalizationStarted{
 			Id:                 e.Id,
 			CongestionTree:     e.CongestionTree,
 			Connectors:         e.Connectors,
 			PoolTx:             e.PoolTx,
 			UnsignedForfeitTxs: forfeitTxs,
 		}
+		s.lastEvent = ev
+		s.eventsCh <- ev
 	case domain.RoundFinalized, domain.RoundFailed:
+		s.lastEvent = e
 		s.eventsCh <- e
 	}
 }
@@ -1118,3 +1271,26 @@ func findForfeitTxBitcoin(
 
 	return "", fmt.Errorf("forfeit tx not found")
 }
+
+// musigSigningSession holds the state of ephemeral nonces and signatures in order to coordinate the signing of the tree
+type musigSigningSession struct {
+	lock        sync.Mutex
+	nbCosigners int
+	nonces      map[*secp256k1.PublicKey]bitcointree.TreeNonces
+	nonceDoneC  chan struct{}
+
+	signatures map[*secp256k1.PublicKey]bitcointree.TreePartialSigs
+	sigDoneC   chan struct{}
+}
+
+func newMusigSigningSession(nbCosigners int) *musigSigningSession {
+	return &musigSigningSession{
+		nonces:     make(map[*secp256k1.PublicKey]bitcointree.TreeNonces),
+		nonceDoneC: make(chan struct{}),
+
+		signatures:  make(map[*secp256k1.PublicKey]bitcointree.TreePartialSigs),
+		sigDoneC:    make(chan struct{}),
+		lock:        sync.Mutex{},
+		nbCosigners: nbCosigners,
+	}
+}

server/internal/core/application/covenantless_event.go

@@ -0,0 +1,43 @@
+/*
+* This package contains intermediary events that are used only by the covenantless version
+* they let to sign the congestion tree using musig2 algorithm
+* they are not included in domain because they don't mutate the Round state and should not be persisted
+ */
+package application
+
+import (
+	"bytes"
+	"encoding/hex"
+
+	"github.com/ark-network/ark/common/bitcointree"
+	"github.com/ark-network/ark/common/tree"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
+)
+
+// signer should react to this event by generating a musig2 nonce for each transaction in the tree
+type RoundSigningStarted struct {
+	Id               string
+	UnsignedVtxoTree tree.CongestionTree
+	Cosigners        []*secp256k1.PublicKey
+}
+
+// signer should react to this event by partially signing the vtxo tree transactions
+// then, delete its ephemeral key
+type RoundSigningNoncesGenerated struct {
+	Id     string
+	Nonces bitcointree.TreeNonces // aggregated nonces
+}
+
+func (e RoundSigningNoncesGenerated) SerializeNonces() (string, error) {
+	var serialized bytes.Buffer
+
+	if err := e.Nonces.Encode(&serialized); err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(serialized.Bytes()), nil
+}
+
+// implement domain.RoundEvent interface
+func (r RoundSigningStarted) IsEvent()         {}
+func (r RoundSigningNoncesGenerated) IsEvent() {}

server/internal/core/application/sweeper.go

@@ -149,7 +149,6 @@ func (s *sweeper) createTask(
 			for _, input := range inputs {
 				// sweepableVtxos related to the sweep input
 				sweepableVtxos := make([]domain.VtxoKey, 0)
-				fmt.Println("input", input.GetHash().String(), input.GetIndex())
 
 				// check if input is the vtxo itself
 				vtxos, _ := s.repoManager.Vtxos().GetVtxos(

server/internal/core/application/types.go

@@ -25,7 +25,7 @@ type Service interface {
 	GetEventsChannel(ctx context.Context) <-chan domain.RoundEvent
 	UpdatePaymentStatus(
 		ctx context.Context, paymentId string,
-	) (unsignedForfeitTxs []string, currentRound *domain.Round, err error)
+	) (lastEvent domain.RoundEvent, err error)
 	ListVtxos(
 		ctx context.Context, pubkey *secp256k1.PublicKey,
 	) (spendableVtxos, spentVtxos []domain.Vtxo, err error)
@@ -41,6 +41,16 @@ type Service interface {
 	CompleteAsyncPayment(
 		ctx context.Context, redeemTx string, unconditionalForfeitTxs []string,
 	) error
+	// Tree signing methods
+	RegisterCosignerPubkey(ctx context.Context, paymentId string, ephemeralPublicKey string) error
+	RegisterCosignerNonces(
+		ctx context.Context, roundID string,
+		pubkey *secp256k1.PublicKey, nonces string,
+	) error
+	RegisterCosignerSignatures(
+		ctx context.Context, roundID string,
+		pubkey *secp256k1.PublicKey, signatures string,
+	) error
 }
 
 type ServiceInfo struct {

server/internal/core/application/utils.go

@@ -10,6 +10,7 @@ import (
 	"github.com/ark-network/ark/common/tree"
 	"github.com/ark-network/ark/server/internal/core/domain"
 	"github.com/ark-network/ark/server/internal/core/ports"
+	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/sirupsen/logrus"
 )
 
@@ -20,8 +21,9 @@ type timedPayment struct {
 }
 
 type paymentsMap struct {
-	lock     *sync.RWMutex
+	lock          *sync.RWMutex
-	payments map[string]*timedPayment
+	payments      map[string]*timedPayment
+	ephemeralKeys map[string]*secp256k1.PublicKey
 }
 
 func newPaymentsMap(payments []domain.Payment) *paymentsMap {
@@ -30,7 +32,7 @@ func newPaymentsMap(payments []domain.Payment) *paymentsMap {
 		paymentsById[p.Id] = &timedPayment{p, time.Now(), time.Time{}}
 	}
 	lock := &sync.RWMutex{}
-	return &paymentsMap{lock, paymentsById}
+	return &paymentsMap{lock, paymentsById, make(map[string]*secp256k1.PublicKey)}
 }
 
 func (m *paymentsMap) len() int64 {
@@ -46,6 +48,18 @@ func (m *paymentsMap) len() int64 {
 	return count
 }
 
+func (m *paymentsMap) delete(id string) error {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	if _, ok := m.payments[id]; !ok {
+		return errPaymentNotFound{id}
+	}
+
+	delete(m.payments, id)
+	return nil
+}
+
 func (m *paymentsMap) push(payment domain.Payment) error {
 	m.lock.Lock()
 	defer m.lock.Unlock()
@@ -58,7 +72,19 @@ func (m *paymentsMap) push(payment domain.Payment) error {
 	return nil
 }
 
-func (m *paymentsMap) pop(num int64) []domain.Payment {
+func (m *paymentsMap) pushEphemeralKey(paymentId string, pubkey *secp256k1.PublicKey) error {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	if _, ok := m.payments[paymentId]; !ok {
+		return fmt.Errorf("payment %s not found, cannot register signing ephemeral public key", paymentId)
+	}
+
+	m.ephemeralKeys[paymentId] = pubkey
+	return nil
+}
+
+func (m *paymentsMap) pop(num int64) ([]domain.Payment, []*secp256k1.PublicKey) {
 	m.lock.Lock()
 	defer m.lock.Unlock()
 
@@ -83,11 +109,16 @@ func (m *paymentsMap) pop(num int64) []domain.Payment {
 	}
 
 	payments := make([]domain.Payment, 0, num)
+	cosigners := make([]*secp256k1.PublicKey, 0, num)
 	for _, p := range paymentsByTime[:num] {
 		payments = append(payments, p.Payment)
+		if pubkey, ok := m.ephemeralKeys[p.Payment.Id]; ok {
+			cosigners = append(cosigners, pubkey)
+			delete(m.ephemeralKeys, p.Payment.Id)
+		}
 		delete(m.payments, p.Id)
 	}
-	return payments
+	return payments, cosigners
 }
 
 func (m *paymentsMap) update(payment domain.Payment) error {

server/internal/core/domain/events.go

@@ -3,14 +3,14 @@ package domain
 import "github.com/ark-network/ark/common/tree"
 
 type RoundEvent interface {
-	isEvent()
+	IsEvent()
 }
 
-func (r RoundStarted) isEvent()             {}
+func (r RoundStarted) IsEvent()             {}
-func (r RoundFinalizationStarted) isEvent() {}
+func (r RoundFinalizationStarted) IsEvent() {}
-func (r RoundFinalized) isEvent()           {}
+func (r RoundFinalized) IsEvent()           {}
-func (r RoundFailed) isEvent()              {}
+func (r RoundFailed) IsEvent()              {}
-func (r PaymentsRegistered) isEvent()       {}
+func (r PaymentsRegistered) IsEvent()       {}
 
 type RoundStarted struct {
 	Id        string

server/internal/interface/grpc/handlers/arkservice.go

@@ -12,6 +12,7 @@ import (
 	"github.com/ark-network/ark/server/internal/core/domain"
 	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/google/uuid"
+	"github.com/sirupsen/logrus"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
@@ -118,25 +119,77 @@ func (h *handler) Ping(ctx context.Context, req *arkv1.PingRequest) (*arkv1.Ping
 		return nil, status.Error(codes.InvalidArgument, "missing payment id")
 	}
 
-	forfeits, round, err := h.svc.UpdatePaymentStatus(ctx, req.GetPaymentId())
+	lastEvent, err := h.svc.UpdatePaymentStatus(ctx, req.GetPaymentId())
 	if err != nil {
 		return nil, err
 	}
 
-	var event *arkv1.RoundFinalizationEvent
+	var resp *arkv1.PingResponse
-	if round != nil {
+
-		event = &arkv1.RoundFinalizationEvent{
+	switch e := lastEvent.(type) {
-			Id:             round.Id,
+	case domain.RoundFinalizationStarted:
-			PoolTx:         round.UnsignedTx,
+		resp = &arkv1.PingResponse{
-			ForfeitTxs:     forfeits,
+			Event: &arkv1.PingResponse_RoundFinalization{
-			CongestionTree: castCongestionTree(round.CongestionTree),
+				RoundFinalization: &arkv1.RoundFinalizationEvent{
-			Connectors:     round.Connectors,
+					Id:             e.Id,
+					PoolTx:         e.PoolTx,
+					CongestionTree: castCongestionTree(e.CongestionTree),
+					ForfeitTxs:     e.UnsignedForfeitTxs,
+					Connectors:     e.Connectors,
+				},
+			},
+		}
+	case domain.RoundFinalized:
+		resp = &arkv1.PingResponse{
+			Event: &arkv1.PingResponse_RoundFinalized{
+				RoundFinalized: &arkv1.RoundFinalizedEvent{
+					Id:       e.Id,
+					PoolTxid: e.Txid,
+				},
+			},
+		}
+	case domain.RoundFailed:
+		resp = &arkv1.PingResponse{
+			Event: &arkv1.PingResponse_RoundFailed{
+				RoundFailed: &arkv1.RoundFailed{
+					Id:     e.Id,
+					Reason: e.Err,
+				},
+			},
+		}
+	case application.RoundSigningStarted:
+		cosignersKeys := make([]string, 0, len(e.Cosigners))
+		for _, key := range e.Cosigners {
+			cosignersKeys = append(cosignersKeys, hex.EncodeToString(key.SerializeCompressed()))
+		}
+
+		resp = &arkv1.PingResponse{
+			Event: &arkv1.PingResponse_RoundSigning{
+				RoundSigning: &arkv1.RoundSigningEvent{
+					Id:               e.Id,
+					CosignersPubkeys: cosignersKeys,
+					UnsignedTree:     castCongestionTree(e.UnsignedVtxoTree),
+				},
+			},
+		}
+	case application.RoundSigningNoncesGenerated:
+		serialized, err := e.SerializeNonces()
+		if err != nil {
+			logrus.WithError(err).Error("failed to serialize nonces")
+			return nil, status.Error(codes.Internal, "failed to serialize nonces")
+		}
+
+		resp = &arkv1.PingResponse{
+			Event: &arkv1.PingResponse_RoundSigningNoncesGenerated{
+				RoundSigningNoncesGenerated: &arkv1.RoundSigningNoncesGeneratedEvent{
+					Id:         e.Id,
+					TreeNonces: serialized,
+				},
+			},
 		}
 	}
-	return &arkv1.PingResponse{
+
-		ForfeitTxs: forfeits,
+	return resp, nil
-		Event:      event,
-	}, nil
 }
 
 func (h *handler) RegisterPayment(ctx context.Context, req *arkv1.RegisterPaymentRequest) (*arkv1.RegisterPaymentResponse, error) {
@@ -150,6 +203,13 @@ func (h *handler) RegisterPayment(ctx context.Context, req *arkv1.RegisterPaymen
 		return nil, err
 	}
 
+	pubkey := req.GetEphemeralPubkey()
+	if len(pubkey) > 0 {
+		if err := h.svc.RegisterCosignerPubkey(ctx, id, pubkey); err != nil {
+			return nil, err
+		}
+	}
+
 	return &arkv1.RegisterPaymentResponse{
 		Id: id,
 	}, nil
@@ -267,14 +327,6 @@ func (h *handler) GetEventStream(_ *arkv1.GetEventStreamRequest, stream arkv1.Ar
 			if err := stream.Send(ev); err != nil {
 				return err
 			}
-
-			switch ev.Event.(type) {
-			case *arkv1.GetEventStreamResponse_RoundFinalized, *arkv1.GetEventStreamResponse_RoundFailed:
-				if err := stream.Send(ev); err != nil {
-					return err
-				}
-				return nil
-			}
 		}
 	}
 }
@@ -312,6 +364,74 @@ func (h *handler) GetInfo(ctx context.Context, req *arkv1.GetInfoRequest) (*arkv
 	}, nil
 }
 
+func (h *handler) SendTreeNonces(ctx context.Context, req *arkv1.SendTreeNoncesRequest) (*arkv1.SendTreeNoncesResponse, error) {
+	pubkey := req.GetPublicKey()
+	encodedNonces := req.GetTreeNonces()
+	roundID := req.GetRoundId()
+
+	if len(pubkey) <= 0 {
+		return nil, status.Error(codes.InvalidArgument, "missing cosigner public key")
+	}
+
+	if len(encodedNonces) <= 0 {
+		return nil, status.Error(codes.InvalidArgument, "missing tree nonces")
+	}
+
+	if len(roundID) <= 0 {
+		return nil, status.Error(codes.InvalidArgument, "missing round id")
+	}
+
+	pubkeyBytes, err := hex.DecodeString(pubkey)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, "invalid cosigner public key")
+	}
+
+	cosignerPublicKey, err := secp256k1.ParsePubKey(pubkeyBytes)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, "invalid cosigner public key")
+	}
+
+	if err := h.svc.RegisterCosignerNonces(ctx, roundID, cosignerPublicKey, encodedNonces); err != nil {
+		return nil, err
+	}
+
+	return &arkv1.SendTreeNoncesResponse{}, nil
+}
+
+func (h *handler) SendTreeSignatures(ctx context.Context, req *arkv1.SendTreeSignaturesRequest) (*arkv1.SendTreeSignaturesResponse, error) {
+	roundID := req.GetRoundId()
+	pubkey := req.GetPublicKey()
+	encodedSignatures := req.GetTreeSignatures()
+
+	if len(pubkey) <= 0 {
+		return nil, status.Error(codes.InvalidArgument, "missing cosigner public key")
+	}
+
+	if len(encodedSignatures) <= 0 {
+		return nil, status.Error(codes.InvalidArgument, "missing tree signatures")
+	}
+
+	if len(roundID) <= 0 {
+		return nil, status.Error(codes.InvalidArgument, "missing round id")
+	}
+
+	pubkeyBytes, err := hex.DecodeString(pubkey)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, "invalid cosigner public key")
+	}
+
+	cosignerPublicKey, err := secp256k1.ParsePubKey(pubkeyBytes)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, "invalid cosigner public key")
+	}
+
+	if err := h.svc.RegisterCosignerSignatures(ctx, roundID, cosignerPublicKey, encodedSignatures); err != nil {
+		return nil, err
+	}
+
+	return &arkv1.SendTreeSignaturesResponse{}, nil
+}
+
 func (h *handler) pushListener(l *listener) {
 	h.listenersLock.Lock()
 	defer h.listenersLock.Unlock()
@@ -368,6 +488,36 @@ func (h *handler) listenToEvents() {
 					},
 				},
 			}
+		case application.RoundSigningStarted:
+			cosignersKeys := make([]string, 0, len(e.Cosigners))
+			for _, key := range e.Cosigners {
+				cosignersKeys = append(cosignersKeys, hex.EncodeToString(key.SerializeCompressed()))
+			}
+
+			ev = &arkv1.GetEventStreamResponse{
+				Event: &arkv1.GetEventStreamResponse_RoundSigning{
+					RoundSigning: &arkv1.RoundSigningEvent{
+						Id:               e.Id,
+						CosignersPubkeys: cosignersKeys,
+						UnsignedTree:     castCongestionTree(e.UnsignedVtxoTree),
+					},
+				},
+			}
+		case application.RoundSigningNoncesGenerated:
+			serialized, err := e.SerializeNonces()
+			if err != nil {
+				logrus.WithError(err).Error("failed to serialize nonces")
+				continue
+			}
+
+			ev = &arkv1.GetEventStreamResponse{
+				Event: &arkv1.GetEventStreamResponse_RoundSigningNoncesGenerated{
+					RoundSigningNoncesGenerated: &arkv1.RoundSigningNoncesGeneratedEvent{
+						Id:         e.Id,
+						TreeNonces: serialized,
+					},
+				},
+			}
 		}
 
 		if ev != nil {

server/internal/interface/grpc/permissions/permissions.go

@@ -161,6 +161,14 @@ func Whitelist() map[string][]bakery.Op {
 			Entity: EntityHealth,
 			Action: "read",
 		}},
+		fmt.Sprintf("/%s/SendTreeNonces", arkv1.ArkService_ServiceDesc.ServiceName): {{
+			Entity: EntityArk,
+			Action: "write",
+		}},
+		fmt.Sprintf("/%s/SendTreeSignatures", arkv1.ArkService_ServiceDesc.ServiceName): {{
+			Entity: EntityArk,
+			Action: "write",
+		}},
 	}
 }