Merge pull request #6602 from BitGo/BTC-2360

feat(utxo-core): add BIP322 message tagged hash implementation

Author: davidkaplanbitgo

modules/utxo-core/package.json

@@ -56,7 +56,8 @@
     "@bitgo/utxo-lib": "^11.6.3",
     "@bitgo/wasm-miniscript": "2.0.0-beta.7",
     "bip174": "npm:@bitgo-forks/[email protected]",
-    "bitcoinjs-message": "npm:@bitgo-forks/[email protected]"
+    "bitcoinjs-message": "npm:@bitgo-forks/[email protected]",
+    "fast-sha256": "^1.3.0"
   },
   "gitHead": "18e460ddf02de2dbf13c2aa243478188fb539f0c"
 }

modules/utxo-core/src/bip322/index.ts

@@ -0,0 +1 @@
+export * from './toSpend';

modules/utxo-core/src/bip322/toSpend.ts

@@ -0,0 +1,24 @@
+import { Hash } from 'fast-sha256';
+
+export const BIP322_TAG = 'BIP0322-signed-message';
+
+/**
+ * Perform a tagged hash
+ *
+ * @param {string | Buffer} message - The message to hash as a Buffer or utf-8 string
+ * @param {Buffer} [tag=BIP322_TAG] - The tag to use for hashing, defaults to BIP322_TAG.
+ * @returns {Buffer} - The resulting hash of the message with the tag.
+ */
+export function hashMessageWithTag(message: string | Buffer, tag = BIP322_TAG): Buffer {
+  // Compute the message hash - SHA256(SHA256(tag) || SHA256(tag) || message)
+  // Reference: https://github.com/bitcoin/bips/blob/master/bip-0322.mediawiki#full
+  const tagHasher = new Hash();
+  tagHasher.update(Buffer.from(BIP322_TAG));
+  const tagHash = tagHasher.digest();
+  const messageHasher = new Hash();
+  messageHasher.update(tagHash);
+  messageHasher.update(tagHash);
+  messageHasher.update(Buffer.from(message));
+  const messageHash = messageHasher.digest();
+  return Buffer.from(messageHash);
+}

modules/utxo-core/src/index.ts

@@ -3,6 +3,7 @@ export * as descriptor from './descriptor';
 export * as testutil from './testutil';
 export * as paygo from './paygo';
 export * as bip32utils from './bip32utils';
+export * as bip322 from './bip322';
 export * from './dustThreshold';
 export * from './Output';
 export * from './xOnlyPubkey';

modules/utxo-core/test/bip322/toSpend.ts

@@ -0,0 +1,30 @@
+import assert from 'assert';
+
+import { hashMessageWithTag } from '../../src/bip322';
+
+describe('to_spend', function () {
+  describe('Message hashing', function () {
+    // Test vectors from BIP322
+    // Source: https://github.com/bitcoin/bips/blob/master/bip-0322.mediawiki#message-hashing
+    const fixtures = [
+      {
+        message: '',
+        hash: 'c90c269c4f8fcbe6880f72a721ddfbf1914268a794cbb21cfafee13770ae19f1',
+      },
+      {
+        message: 'Hello World',
+        hash: 'f0eb03b1a75ac6d9847f55c624a99169b5dccba2a31f5b23bea77ba270de0a7a',
+      },
+    ];
+    fixtures.forEach(({ message, hash }) => {
+      it(`should hash the message "${message}"`, function () {
+        const result = hashMessageWithTag(Buffer.from(message));
+        assert.deepStrictEqual(
+          result.toString('hex'),
+          hash,
+          `Hash for message "${message}" does not match expected value`
+        );
+      });
+    });
+  });
+});