Merge pull request #7409 from BitGo/BTC-2652.add-musig2-fixtures

feat(utxo-lib): add cross-validation tests for MuSig2 implementation

Author: OttoAllmendinger

modules/utxo-lib/bip-0327/.gitignore

@@ -0,0 +1 @@
+__pycache__/

modules/utxo-lib/bip-0327/README.md

@@ -171,6 +171,37 @@ The test suite runs:
 4. BitGo legacy p2tr tests
 5. BitGo standard p2trMusig2 tests
 
+### TypeScript Cross-Validation Tests
+
+The `test_typescript_fixtures.py` script validates that the Python reference implementation produces identical results to the TypeScript implementation:
+
+```bash
+cd modules/utxo-lib/bip-0327
+python3 test_typescript_fixtures.py
+```
+
+These tests read JSON fixtures from the `musig2/` directory, which are generated by the TypeScript test suite in `test/bitgo/psbt/Musig2Methods.ts`. The fixtures contain:
+
+- **createTapInternalKey.json** - Key aggregation results
+- **createTapOutputKey.json** - Tweaked aggregate key results
+- **createTapTweak.json** - Taproot tweak computation
+- **createAggregateNonce.json** - Nonce aggregation results
+- **createMusig2SigningSession.json** - Session context creation
+- **musig2PartialSignAndVerify.json** - Partial signature verification
+- **musig2AggregateSigs.json** - Signature aggregation and final verification
+- **fullSigningFlow.json** - Complete end-to-end signing workflow
+
+The cross-validation tests ensure that:
+1. Key aggregation produces identical aggregate public keys
+2. Taproot tweaking produces identical output keys
+3. Deterministic nonce generation produces identical nonces (using session IDs `0x0101...` and `0x0202...`)
+4. Partial signature generation produces identical signatures
+5. Partial signature verification works identically
+6. Signature aggregation produces identical results
+7. Final Schnorr signature verification succeeds in both implementations
+
+The tests use fully deterministic nonce generation with fixed session IDs to ensure bit-for-bit identical outputs between Python and TypeScript. This provides strong confidence that the TypeScript and Python implementations are compatible and produce identical cryptographic outputs at every step of the MuSig2 protocol.
+
 ## References
 
 - [BIP327 Specification](https://github.com/bitcoin/bips/blob/master/bip-0327.mediawiki)

modules/utxo-lib/bip-0327/test_typescript_fixtures.py

@@ -5,4 +5,5 @@ set -e
 cd "$(dirname "$0")"
 mypy --no-error-summary reference.py
 python3 reference.py
+python3 test_typescript_fixtures.py
 python3 gen_vectors_helper.py > /dev/null

modules/utxo-lib/bip-0327/tests.sh

@@ -0,0 +1 @@
+../test/bitgo/fixtures/musig2

modules/utxo-lib/bip-0327/utxolibMusig2

@@ -0,0 +1,11 @@
+{
+  "inputs": {
+    "pubNonces": [
+      "027389d7aa456cbe418467f42928601462d77000c3b260e5127f1111b57588b35e036f13a501e1708aa7288a313d71975324e0de1d129acff61e40e1c96ae5976c29",
+      "02949960a953f58a5bad40d8c6161bac10a52a971a37cfe858ba4a1452524b1691026dca4ba06a76389621d0d5a6965976120eb9dac6b861cf32d674c65e080a7c13"
+    ]
+  },
+  "output": {
+    "aggregateNonce": "0233086bdf4150163179ef61beed827f55b073563e8bde58755ed8bcddc00635a902418bed8a65d3ee02007694fb18b5a1ec202d8b69ece07e2d54dd193ef7373b88"
+  }
+}

modules/utxo-lib/test/bitgo/fixtures/musig2/createAggregateNonce.json

@@ -0,0 +1,22 @@
+{
+  "inputs": {
+    "pubNonces": [
+      "027389d7aa456cbe418467f42928601462d77000c3b260e5127f1111b57588b35e036f13a501e1708aa7288a313d71975324e0de1d129acff61e40e1c96ae5976c29",
+      "02949960a953f58a5bad40d8c6161bac10a52a971a37cfe858ba4a1452524b1691026dca4ba06a76389621d0d5a6965976120eb9dac6b861cf32d674c65e080a7c13"
+    ],
+    "txHash": "d11d3b06a83bb14c95fad947da2192ad9f6faee3c0fb36ad197a05f943aa7acd",
+    "pubKeys": [
+      "03e9fc8f605f59d6a4f5ceb0d27852151013f2bf1965f9adf44ce9ba9821c7f106",
+      "030710ec162d2199bb828e5d8760f16d65412bbb2c85ec13fe027f77d83a349c62"
+    ],
+    "internalPubKey": "6d767a69e03d4611485407d777711ee4d1321a84cf82f591db0cd3e179c49821",
+    "tapTreeRoot": "63a3684763dca2d4bb5d412d01f5ce73214af3d7816b52d7ad549562cc4cd890"
+  },
+  "output": {
+    "sessionKey": {
+      "aggNonce": "0233086bdf4150163179ef61beed827f55b073563e8bde58755ed8bcddc00635a902418bed8a65d3ee02007694fb18b5a1ec202d8b69ece07e2d54dd193ef7373b88",
+      "msg": "d11d3b06a83bb14c95fad947da2192ad9f6faee3c0fb36ad197a05f943aa7acd",
+      "publicKey": "04e5406bdcc45b02e86b30c446fd57375e8bfc8144238d61033d353c8a3641a43d5bc152f290f28255baf6bf18c5de0d67f81921fc4e1c05c3c5625eb7784eab01"
+    }
+  }
+}

modules/utxo-lib/test/bitgo/fixtures/musig2/createMusig2SigningSession.json

@@ -0,0 +1,11 @@
+{
+  "inputs": {
+    "pubKeys": [
+      "03e9fc8f605f59d6a4f5ceb0d27852151013f2bf1965f9adf44ce9ba9821c7f106",
+      "030710ec162d2199bb828e5d8760f16d65412bbb2c85ec13fe027f77d83a349c62"
+    ]
+  },
+  "output": {
+    "tapInternalKey": "6d767a69e03d4611485407d777711ee4d1321a84cf82f591db0cd3e179c49821"
+  }
+}

modules/utxo-lib/test/bitgo/fixtures/musig2/createTapInternalKey.json

@@ -0,0 +1,9 @@
+{
+  "inputs": {
+    "internalPubKey": "6d767a69e03d4611485407d777711ee4d1321a84cf82f591db0cd3e179c49821",
+    "tapTreeRoot": "63a3684763dca2d4bb5d412d01f5ce73214af3d7816b52d7ad549562cc4cd890"
+  },
+  "output": {
+    "tapOutputKey": "e5406bdcc45b02e86b30c446fd57375e8bfc8144238d61033d353c8a3641a43d"
+  }
+}

modules/utxo-lib/test/bitgo/fixtures/musig2/createTapOutputKey.json

@@ -0,0 +1,9 @@
+{
+  "inputs": {
+    "tapInternalKey": "6d767a69e03d4611485407d777711ee4d1321a84cf82f591db0cd3e179c49821",
+    "tapMerkleRoot": "63a3684763dca2d4bb5d412d01f5ce73214af3d7816b52d7ad549562cc4cd890"
+  },
+  "output": {
+    "tapTweak": "c990a77a31b07eea9d1a616bfe80bd33ba2a7e2a22db0e900a168d87a5e01a2c"
+  }
+}