Update NUT-29 signature message to include mint pubkey and timestamp

tests/29-test.md

@@ -0,0 +1,38 @@
+# NUT-29 Test Vectors
+
+## Request Signature Validation
+
+The following test vectors can be used to verify the signature required for the `POST /v1/mint/quote/{method}/pubkey` request.
+
+The user generates a private key and derives the public key:
+
+`private_key`: `1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef`
+`pubkey`: `02bb50e2d89a4ed70663d080659fe0ad4b9bc3e06c17a227433966cb59ceee020d`
+
+The user wants to look up quotes for this public key. The request contains the following parameters:
+
+`timestamp`: `1714521600`
+`mint_pubkey`: `0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798`
+
+The message to sign `msg_to_sign` is the concatenation of `pubkey || timestamp || mint_pubkey`:
+`msg_to_sign`: `02bb50e2d89a4ed70663d080659fe0ad4b9bc3e06c17a227433966cb59ceee020d17145216000279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798`
+
+The SHA-256 hash of `msg_to_sign` is:
+`hash`: `8802cf9f257a9d8e9ad702b2eb6e6b98016b866ae6d8593840c0cfa115985d3e`
+
+The Schnorr signature (BIP340) on the `hash` using the `private_key` is:
+`signature`: `51efc2cedc082bce9780cf428f534a008150e699383b017950944271bfd8806a01eeb7a3833187d25c675062239cbd6567ca1d28dd2c38f841debee8524b9b9a`
+
+The wallet sends the following `PostMintQuotesByPubkeyRequest`:
+
+```json
+{
+  "pubkeys": [
+    "02bb50e2d89a4ed70663d080659fe0ad4b9bc3e06c17a227433966cb59ceee020d"
+  ],
+  "pubkey_signatures": [
+    "51efc2cedc082bce9780cf428f534a008150e699383b017950944271bfd8806a01eeb7a3833187d25c675062239cbd6567ca1d28dd2c38f841debee8524b9b9a"
+  ],
+  "timestamp": 1714521600
+}
+```

xx.md

@@ -21,14 +21,16 @@ The wallet includes the following `PostMintQuotesByPubkeyRequest` data:
 ```json
 {
   "pubkeys": <Array[str]>,
-  "pubkey_signatures": <Array[str]>
+  "pubkey_signatures": <Array[str]>,
+  "timestamp": <int>
 }
 ```
 
 - `pubkeys` is an array of hex-encoded compressed secp256k1 NUT-20 public keys (33 bytes each)
-- `pubkey_signatures` is an array of hex-encoded Schnorr signatures on `pubkeys` in the same order (64 bytes each)
+- `pubkey_signatures` is an array of hex-encoded Schnorr signatures in the same order (64 bytes each)
+- `timestamp` is the current Unix timestamp in seconds
 
-The wallet **MUST** provide a valid signature in `pubkey_signatures` for each public key in `pubkeys` with the corresponding private key in the same order as the `pubkeys` array. The message to sign is the byte representation of the public key.
+The wallet **MUST** provide a valid signature in `pubkey_signatures` for each public key in `pubkeys` with the corresponding private key in the same order as the `pubkeys` array. The message to sign is the SHA-256 hash of the concatenated string `pubkey || timestamp || mint_pubkey`. Where `||` denotes concatenation, `pubkey` is the hex-encoded public key, `timestamp` is the UTF-8 string representation of the Unix timestamp, and `mint_pubkey` is the hex-encoded public key of the mint as defined in [NUT-06][06].
 
 ## Response