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lightningd: new api payersign to sign bolt12 message with a payer_key.

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Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2021-01-08 05:07:47 +10:30
parent f2d2db7b4e
commit c1b38afcd3
1 changed files with 90 additions and 40 deletions
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130
lightningd/offer.c
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@@ -7,6 +7,7 @@
#include <hsmd/hsmd_wiregen.h>
#include <lightningd/jsonrpc.h>
#include <lightningd/lightningd.h>
#include <secp256k1_schnorrsig.h>
#include <wallet/wallet.h>
#include <wire/wire_sync.h>
@@ -43,14 +44,19 @@ static struct command_result *param_b12_offer(struct command *cmd,
return NULL;
}
static void hsm_sign_b12_offer(struct lightningd *ld,
const struct sha256 *merkle,
struct bip340sig *sig)
static void hsm_sign_b12(struct lightningd *ld,
const char *messagename,
const char *fieldname,
const struct sha256 *merkle,
const u8 *publictweak,
const struct pubkey32 *key,
struct bip340sig *sig)
{
u8 *msg;
struct sha256 sighash;
msg = towire_hsmd_sign_bolt12(NULL, "offer", "signature", merkle, NULL);
msg = towire_hsmd_sign_bolt12(NULL, messagename, fieldname, merkle,
publictweak);
if (!wire_sync_write(ld->hsm_fd, take(msg)))
fatal("Could not write to HSM: %s", strerror(errno));
@@ -58,6 +64,14 @@ static void hsm_sign_b12_offer(struct lightningd *ld,
if (!fromwire_hsmd_sign_bolt12_reply(msg, sig))
fatal("HSM gave bad sign_offer_reply %s",
tal_hex(msg, msg));
/* Now we sanity-check! */
sighash_from_merkle(messagename, fieldname, merkle, &sighash);
if (secp256k1_schnorrsig_verify(secp256k1_ctx, sig->u8,
sighash.u.u8, &key->pubkey) != 1)
fatal("HSM gave bad signature %s for pubkey %s",
type_to_string(tmpctx, struct bip340sig, sig),
type_to_string(tmpctx, struct pubkey32, key));
}
static struct command_result *json_createoffer(struct command *cmd,
@@ -72,6 +86,7 @@ static struct command_result *json_createoffer(struct command *cmd,
const char *b12str;
bool *single_use;
enum offer_status status;
struct pubkey32 key;
if (!param(cmd, buffer, params,
p_req("bolt12", param_b12_offer, &offer),
@@ -86,7 +101,10 @@ static struct command_result *json_createoffer(struct command *cmd,
status = OFFER_MULTIPLE_USE;
merkle_tlv(offer->fields, &merkle);
offer->signature = tal(offer, struct bip340sig);
hsm_sign_b12_offer(cmd->ld, &merkle, offer->signature);
if (!pubkey32_from_node_id(&key, &cmd->ld->id))
fatal("invalid own node_id?");
hsm_sign_b12(cmd->ld, "offer", "signature", &merkle, NULL, &key,
offer->signature);
b12str = offer_encode(cmd, offer);
if (!wallet_offer_create(cmd->ld->wallet, &merkle, b12str, label,
status)) {
@@ -315,6 +333,28 @@ static struct command_result *param_b12_invreq(struct command *cmd,
return NULL;
}
static bool payer_key(struct lightningd *ld,
const u8 *public_tweak, size_t public_tweak_len,
struct pubkey32 *key)
{
struct sha256 tweakhash;
secp256k1_pubkey tweaked;
payer_key_tweak(&ld->bolt12_base, public_tweak, public_tweak_len,
&tweakhash);
/* Tweaking gives a not-x-only pubkey, must then convert. */
if (secp256k1_xonly_pubkey_tweak_add(secp256k1_ctx,
&tweaked,
&ld->bolt12_base.pubkey,
tweakhash.u.u8) != 1)
return false;
return secp256k1_xonly_pubkey_from_pubkey(secp256k1_ctx,
&key->pubkey,
NULL, &tweaked) == 1;
}
static struct command_result *json_createinvoicerequest(struct command *cmd,
const char *buffer,
const jsmntok_t *obj,
@@ -322,9 +362,7 @@ static struct command_result *json_createinvoicerequest(struct command *cmd,
{
struct tlv_invoice_request *invreq;
const char *label;
struct sha256 tweakhash;
struct json_stream *response;
secp256k1_pubkey tweaked;
if (!param(cmd, buffer, params,
p_req("bolt12", param_b12_invreq, &invreq),
@@ -360,25 +398,13 @@ static struct command_result *json_createinvoicerequest(struct command *cmd,
tal_bytelen(invreq->payer_info));
}
payer_key_tweak(&cmd->ld->bolt12_base,
invreq->payer_info, tal_bytelen(invreq->payer_info),
&tweakhash);
/* Tweaking gives a not-x-only pubkey, must then convert. */
if (secp256k1_xonly_pubkey_tweak_add(secp256k1_ctx,
&tweaked,
&cmd->ld->bolt12_base.pubkey,
tweakhash.u.u8) != 1) {
invreq->payer_key = tal(invreq, struct pubkey32);
if (!payer_key(cmd->ld,
invreq->payer_info, tal_bytelen(invreq->payer_info),
invreq->payer_key)) {
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
"Invalid tweak");
}
invreq->payer_key = tal(invreq, struct pubkey32);
if (secp256k1_xonly_pubkey_from_pubkey(secp256k1_ctx,
&invreq->payer_key->pubkey,
NULL, &tweaked) != 1) {
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
"Invalid tweaked key");
}
/* BOLT-offers #12:
* - if the offer contained `recurrence`:
@@ -389,27 +415,14 @@ static struct command_result *json_createinvoicerequest(struct command *cmd,
*/
if (invreq->recurrence_counter) {
struct sha256 merkle;
u8 *msg;
/* This populates the ->fields from our entries */
invreq->fields = tlv_make_fields(invreq, invoice_request);
merkle_tlv(invreq->fields, &merkle);
msg = towire_hsmd_sign_bolt12(NULL,
"invoice_request",
"recurrence_signature",
&merkle, invreq->payer_info);
if (!wire_sync_write(cmd->ld->hsm_fd, take(msg)))
fatal("Could not write to HSM: %s", strerror(errno));
msg = wire_sync_read(tmpctx, cmd->ld->hsm_fd);
invreq->recurrence_signature = tal(invreq, struct bip340sig);
if (!fromwire_hsmd_sign_bolt12_reply(msg,
invreq->recurrence_signature))
fatal("HSM gave bad sign_offer_reply %s",
tal_hex(msg, msg));
/* FIXME: Validate signature! */
hsm_sign_b12(cmd->ld, "invoice_request", "recurrence_signature",
&merkle, invreq->payer_info, invreq->payer_key,
invreq->recurrence_signature);
}
response = json_stream_success(cmd);
@@ -427,3 +440,40 @@ static const struct json_command createinvreq_command = {
"Create and sign an invoice_request {bolt12}, with {recurrence_label} if recurring, filling in payer_info and payer_key."
};
AUTODATA(json_command, &createinvreq_command);
static struct command_result *json_payersign(struct command *cmd,
const char *buffer,
const jsmntok_t *obj UNNEEDED,
const jsmntok_t *params)
{
struct json_stream *response;
struct sha256 *merkle;
u8 *tweak;
struct bip340sig sig;
const char *messagename, *fieldname;
struct pubkey32 key;
if (!param(cmd, buffer, params,
p_req("messagename", param_string, &messagename),
p_req("fieldname", param_string, &fieldname),
p_req("merkle", param_sha256, &merkle),
p_req("tweak", param_bin_from_hex, &tweak),
NULL))
return command_param_failed();
payer_key(cmd->ld, tweak, tal_bytelen(tweak), &key);
hsm_sign_b12(cmd->ld, messagename, fieldname, merkle,
tweak, &key, &sig);
response = json_stream_success(cmd);
json_add_string(response, "signature", fmt_bip340sig(tmpctx, &sig));
return command_success(cmd, response);
}
static const struct json_command payersign_command = {
"payersign",
"payment",
json_payersign,
"Sign {messagename} {fieldname} {merkle} (a 32-byte hex string) using public {tweak}",
};
AUTODATA(json_command, &payersign_command);