Seed encrypt: init mint with encrypted keys after migration (#472)

* seed encrypt: init mint with encrypted keys after migration

* adjust build pipeline

.github/workflows/docker.yaml

@@ -21,6 +21,15 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
+      - name: Cache Docker layers
+        uses: actions/cache@v4
+        id: cache
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-
+
       - name: Determine Tag
         id: get_tag
         run: |
@@ -36,3 +45,6 @@ jobs:
           context: .
           push: ${{ github.event_name == 'release' }}
           tags: ${{ secrets.DOCKER_USERNAME }}/${{ github.event.repository.name }}:${{ steps.get_tag.outputs.tag }}
+          platforms: linux/amd64,linux/arm64
+          cache-from: type=local,src=/tmp/.buildx-cache
+          cache-to: type=local,dest=/tmp/.buildx-cache

cashu/core/crypto/keys.py

@@ -16,8 +16,7 @@ def derive_keys(mnemonic: str, derivation_path: str):
     bip32 = BIP32.from_seed(mnemonic.encode())
     orders_str = [f"/{i}'" for i in range(settings.max_order)]
     return {
-        2
-        ** i: PrivateKey(
+        2**i: PrivateKey(
             bip32.get_privkey_from_path(derivation_path + orders_str[i]),
             raw=True,
         )
@@ -25,26 +24,25 @@ def derive_keys(mnemonic: str, derivation_path: str):
     }
 
 
-def derive_keys_sha256(master_key: str, derivation_path: str = ""):
+def derive_keys_sha256(seed: str, derivation_path: str = ""):
     """
     Deterministic derivation of keys for 2^n values.
     TODO: Implement BIP32.
     """
     return {
-        2
-        ** i: PrivateKey(
-            hashlib.sha256(
-                (master_key + derivation_path + str(i)).encode("utf-8")
-            ).digest()[:32],
+        2**i: PrivateKey(
+            hashlib.sha256((seed + derivation_path + str(i)).encode("utf-8")).digest()[
+                :32
+            ],
             raw=True,
         )
         for i in range(settings.max_order)
     }
 
 
-def derive_pubkey(master_key: str):
+def derive_pubkey(seed: str):
     return PrivateKey(
-        hashlib.sha256((master_key).encode("utf-8")).digest()[:32],
+        hashlib.sha256((seed).encode("utf-8")).digest()[:32],
         raw=True,
     ).pubkey
 

cashu/core/legacy.py

@@ -6,15 +6,14 @@ from ..core.settings import settings
 
 
 def derive_keys_backwards_compatible_insecure_pre_0_12(
-    master_key: str, derivation_path: str = ""
+    seed: str, derivation_path: str = ""
 ):
     """
     WARNING: Broken key derivation for backwards compatibility with 0.11.
     """
     return {
-        2
-        ** i: PrivateKey(
-            hashlib.sha256((master_key + derivation_path + str(i)).encode("utf-8"))
+        2**i: PrivateKey(
+            hashlib.sha256((seed + derivation_path + str(i)).encode("utf-8"))
             .hexdigest()
             .encode("utf-8")[:32],
             raw=True,

cashu/mint/encrypt.py

@@ -146,6 +146,17 @@ async def migrate(no_dry_run):
                         keyset_dict["id"],
                     ),
                 )
+
+        click.echo("Initializing mint with encrypted seeds.")
+        encrypted_mint_private_key = aes.encrypt(settings.mint_private_key.encode())
+        ledger = Ledger(
+            db=Database("mint", settings.mint_database),
+            seed=encrypted_mint_private_key,
+            seed_decryption_key=settings.mint_seed_decryption_key,
+            derivation_path=settings.mint_derivation_path,
+            backends={},
+            crud=LedgerCrudSqlite(),
+        )
         click.echo("✅ Migration complete.")
 
 

cashu/mint/ledger.py

@@ -76,17 +76,22 @@ class Ledger(LedgerVerification, LedgerSpendingConditions):
         assert seed, "seed not set"
 
         # decrypt seed if seed_decryption_key is set
-        self.master_key = (
-            AESCipher(seed_decryption_key).decrypt(seed)
-            if seed_decryption_key
-            else seed
-        )
+        try:
+            self.seed = (
+                AESCipher(seed_decryption_key).decrypt(seed)
+                if seed_decryption_key
+                else seed
+            )
+        except Exception as e:
+            raise Exception(
+                f"Could not decrypt seed. Make sure that the seed is correct and the decryption key is set. {e}"
+            )
         self.derivation_path = derivation_path
 
         self.db = db
         self.crud = crud
         self.backends = backends
-        self.pubkey = derive_pubkey(self.master_key)
+        self.pubkey = derive_pubkey(self.seed)
         self.spent_proofs: Dict[str, Proof] = {}
 
     # ------- KEYS -------
@@ -109,7 +114,7 @@ class Ledger(LedgerVerification, LedgerSpendingConditions):
             MintKeyset: Keyset
         """
         assert derivation_path, "derivation path not set"
-        seed = seed or self.master_key
+        seed = seed or self.seed
         tmp_keyset_local = MintKeyset(
             seed=seed,
             derivation_path=derivation_path,
@@ -132,7 +137,7 @@ class Ledger(LedgerVerification, LedgerSpendingConditions):
             # no keyset for this derivation path yet
             # we create a new keyset (keys will be generated at instantiation)
             keyset = MintKeyset(
-                seed=seed or self.master_key,
+                seed=seed or self.seed,
                 derivation_path=derivation_path,
                 version=version or settings.version,
             )