fix(sdk-core): pass round to getBitgoSignatureShare helper

Ticket: WCI-626
EdDSA MPCv2 signing can receive multiple BitGo-to-signer shares in a txRequest.
Selecting only by sender/recipient can pick a stale round-1 output during round 2.
- Add shareType param to getBitgoSignatureShare to filter by round output type.
- Update EdDSA MPCv2 callers to request round-1 or round-2 output explicitly.
- Remove inline reverse().find() in offline round-3 path in favour of the helper.
- Update tests to expect round-specific missing share error messages.

Author: vibhavgo

modules/sdk-core/src/bitgo/tss/common.ts

@@ -1,6 +1,7 @@
 import assert from 'assert';
 import openpgp from 'openpgp';
 
+import { MPCv2SigningState } from '@bitgo/public-types';
 import { BitGoBase } from '../bitgoBase';
 import { TxRequestChallengeResponse } from './types';
 import {
@@ -20,12 +21,21 @@ const debug = require('debug')('bitgo:tss:common');
 
 export function getBitgoSignatureShare(
   signatureShares: SignatureShareRecord[],
-  signerShareType: SignatureShareType
+  signerShareType: SignatureShareType,
+  shareType: MPCv2SigningState
 ): SignatureShareRecord {
-  const bitgoShare = signatureShares.find(
-    (share) => share.from === SignatureShareType.BITGO && share.to === signerShareType
-  );
-  assert(bitgoShare, 'Missing BitGo signature share');
+  const bitgoShare = signatureShares.find((share) => {
+    if (share.from !== SignatureShareType.BITGO || share.to !== signerShareType) {
+      return false;
+    }
+
+    try {
+      return JSON.parse(share.share).type === shareType;
+    } catch {
+      return false;
+    }
+  });
+  assert(bitgoShare, `Missing BitGo ${shareType} signature share`);
   return bitgoShare;
 }
 

modules/sdk-core/src/bitgo/utils/tss/eddsa/eddsaMPCv2.ts

@@ -469,7 +469,7 @@ export class EddsaMPCv2Utils extends BaseEddsaUtils {
         ? latestTxRequest.transactions![0].signatureShares
         : latestTxRequest.messages![0].signatureShares;
 
-    const bitgoShareRoundOne = getBitgoSignatureShare(signatureShares1, signerShareType);
+    const bitgoShareRoundOne = getBitgoSignatureShare(signatureShares1, signerShareType, 'round1Output');
     const parsedBitGoToUserSigShareRoundOne = decodeWithCodec(
       EddsaMPCv2SignatureShareRound1Output,
       JSON.parse(bitgoShareRoundOne.share),
@@ -508,7 +508,7 @@ export class EddsaMPCv2Utils extends BaseEddsaUtils {
         ? latestTxRequest.transactions![0].signatureShares
         : latestTxRequest.messages![0].signatureShares;
 
-    const bitgoShareRoundTwo = getBitgoSignatureShare(txRequestSignatureShares, signerShareType);
+    const bitgoShareRoundTwo = getBitgoSignatureShare(txRequestSignatureShares, signerShareType, 'round2Output');
     const parsedBitGoToUserSigShareRoundTwo = decodeWithCodec(
       EddsaMPCv2SignatureShareRound2Output,
       JSON.parse(bitgoShareRoundTwo.share),
@@ -649,7 +649,7 @@ export class EddsaMPCv2Utils extends BaseEddsaUtils {
     const signatureShares = transactions[0].signatureShares;
     assert(signatureShares, 'Missing signature shares in round 1 txRequest');
 
-    const bitgoShareRoundOne = getBitgoSignatureShare(signatureShares, SignatureShareType.USER);
+    const bitgoShareRoundOne = getBitgoSignatureShare(signatureShares, SignatureShareType.USER, 'round1Output');
     const parsedBitGoToUserSigShareRoundOne = decodeWithCodec(
       EddsaMPCv2SignatureShareRound1Output,
       JSON.parse(bitgoShareRoundOne.share),
@@ -754,18 +754,7 @@ export class EddsaMPCv2Utils extends BaseEddsaUtils {
     const signatureShares = transactions[0].signatureShares;
     assert(signatureShares, 'Missing signature shares in round 2 txRequest');
 
-    const bitgoShareRoundTwo = [...signatureShares].reverse().find((share) => {
-      if (share.from !== SignatureShareType.BITGO || share.to !== SignatureShareType.USER) {
-        return false;
-      }
-
-      try {
-        return JSON.parse(share.share).type === 'round2Output';
-      } catch {
-        return false;
-      }
-    });
-    assert(bitgoShareRoundTwo, 'Missing BitGo round 2 signature share');
+    const bitgoShareRoundTwo = getBitgoSignatureShare(signatureShares, SignatureShareType.USER, 'round2Output');
 
     const parsedBitGoToUserSigShareRoundTwo = decodeWithCodec(
       EddsaMPCv2SignatureShareRound2Output,

modules/sdk-core/test/unit/bitgo/utils/tss/eddsa/eddsaMPCv2.ts

@@ -32,6 +32,7 @@ import {
   verifyPeerMessageRoundOne,
   verifyPeerMessageRoundTwo,
 } from '../../../../../../src/bitgo/tss/eddsa/eddsaMPCv2';
+import { getBitgoSignatureShare } from '../../../../../../src/bitgo/tss/common';
 import { decodeWithCodec } from '../../../../../../src/bitgo/utils/codecs';
 import { generateGPGKeyPair } from '../../../../../../src/bitgo/utils/opengpgUtils';
 import { MPCv2PartiesEnum } from '../../../../../../src/bitgo/utils/tss/ecdsa/typesMPCv2';
@@ -799,7 +800,7 @@ describe('EddsaMPCv2Utils.createOfflineRound2Share', () => {
           encryptedUserGpgPrvKey: round1.encryptedUserGpgPrvKey,
           encryptedRound1Session: round1.encryptedRound1Session,
         }),
-      /Missing BitGo signature share/
+      /Missing BitGo round1Output signature share/
     );
   });
 
@@ -1114,7 +1115,7 @@ describe('EddsaMPCv2Utils.createOfflineRound3Share', () => {
           encryptedUserGpgPrvKey: round1.encryptedUserGpgPrvKey,
           encryptedRound2Session: round2.encryptedRound2Session,
         }),
-      /Missing BitGo round 2 signature share/
+      /Missing BitGo round2Output signature share/
     );
   });
 
@@ -1151,6 +1152,45 @@ describe('EddsaMPCv2Utils.createOfflineRound3Share', () => {
   });
 });
 
+describe('getBitgoSignatureShare', () => {
+  const round1OutputShare: SignatureShareRecord = {
+    from: SignatureShareType.BITGO,
+    to: SignatureShareType.USER,
+    share: JSON.stringify({ type: 'round1Output', data: {} }),
+  };
+  const round2OutputShare: SignatureShareRecord = {
+    from: SignatureShareType.BITGO,
+    to: SignatureShareType.USER,
+    share: JSON.stringify({ type: 'round2Output', data: {} }),
+  };
+
+  it('selects the requested BitGo round output when multiple round outputs are present', () => {
+    const signatureShares = [round1OutputShare, round2OutputShare];
+
+    assert.strictEqual(
+      getBitgoSignatureShare(signatureShares, SignatureShareType.USER, 'round2Output'),
+      round2OutputShare
+    );
+    assert.strictEqual(
+      getBitgoSignatureShare(signatureShares, SignatureShareType.USER, 'round1Output'),
+      round1OutputShare
+    );
+  });
+
+  it('skips malformed share records while selecting the requested BitGo round output', () => {
+    const malformedShare: SignatureShareRecord = {
+      from: SignatureShareType.BITGO,
+      to: SignatureShareType.USER,
+      share: 'not-json',
+    };
+
+    assert.strictEqual(
+      getBitgoSignatureShare([malformedShare, round2OutputShare], SignatureShareType.USER, 'round2Output'),
+      round2OutputShare
+    );
+  });
+});
+
 type TxRequestTransaction = NonNullable<TxRequest['transactions']>[number];
 
 function assertSingleTransaction(txRequest: TxRequest): TxRequestTransaction {