feat: narrow EdDSA MPC R/G share API and keep full state on AWM

src/__tests__/api/advancedWalletManager/signMpcTransaction.test.ts

@@ -186,13 +186,13 @@ describe('signMpcTransaction', () => {
         .send(rInput);
 
       rResponse.status.should.equal(200);
-      rResponse.body.should.have.property('rShare');
+      rResponse.body.rShare.should.have.only.keys('i', 'j', 'r', 'R', 'commitment');
+      rResponse.body.rShare.i.should.equal(3);
+      rResponse.body.rShare.j.should.equal(1);
 
       rKeyProviderNock.done();
       decryptDataKeyNock.done();
 
-      // Continue with G share test using the returned rShare
-      const rShare = rResponse.body.rShare;
       const derivationPath = 'm/0';
       const tMessage = 'testMessage';
 
@@ -227,7 +227,8 @@ describe('signMpcTransaction', () => {
         source: 'user',
         pub: 'DSqMPMsMAbEJVNuPKv1ZFdzt6YvJaDPDddfeW7ajtqds',
         txRequest: mockTxRequest,
-        userToBitgoRShare: rShare,
+        encryptedUserToBitgoRShare,
+        encryptedDataKey,
         bitgoToUserRShare: signatureShareRec,
         bitgoToUserCommitment: bitgoToUserCommitmentShare,
       };
@@ -238,6 +239,10 @@ describe('signMpcTransaction', () => {
         .query({ source: 'user' })
         .reply(200, mockKeyProviderResponse);
 
+      const gDecryptDataKeyNock = nock(keyProviderUrl)
+        .post('/decryptDataKey')
+        .reply(200, mockDecryptedDataKeyResponse);
+
       const gResponse = await agent
         .post(`/api/${coin}/mpc/sign/g`)
         .set('Authorization', `Bearer ${accessToken}`)
@@ -251,6 +256,33 @@ describe('signMpcTransaction', () => {
       gResponse.body.gShare.should.have.property('R');
 
       gKeyProviderNock.done();
+      gDecryptDataKeyNock.done();
+    });
+
+    it('should fail G share generation without the encrypted commitment round state', async () => {
+      const input = {
+        source: 'user',
+        pub: 'DSqMPMsMAbEJVNuPKv1ZFdzt6YvJaDPDddfeW7ajtqds',
+        txRequest: mockTxRequest,
+        bitgoToUserRShare: { from: 'bitgo', to: 'user', share: 'r-share' },
+        bitgoToUserCommitment: { from: 'bitgo', to: 'user', share: 'commitment' },
+      };
+
+      const keyProviderNock = nock(keyProviderUrl)
+        .get(`/key/${input.pub}`)
+        .query({ source: 'user' })
+        .reply(200, { prv: 'mock-prv', pub: input.pub, source: 'user', type: 'independent' });
+
+      const response = await agent
+        .post(`/api/${coin}/mpc/sign/g`)
+        .set('Authorization', `Bearer ${accessToken}`)
+        .send(input);
+
+      response.status.should.equal(500);
+      response.body.details.should.equal(
+        'encryptedUserToBitgoRShare is required for G share generation',
+      );
+      keyProviderNock.done();
     });
 
     it('should fail when key provider returns no private key', async () => {

src/__tests__/api/master/eddsa.test.ts

@@ -117,6 +117,7 @@ describe('Eddsa Signing Handler', () => {
     const offerRShareNock = nock(bitgoApiUrl)
       .post(
         `/api/v2/wallet/${walletId}/txrequests/test-tx-request-id/transactions/0/signatureshares`,
+        (body) => body.signatureShare?.share === 'r-shareR-share',
       )
       .matchHeader('any', () => true)
       .reply(200, {
@@ -203,19 +204,18 @@ describe('Eddsa Signing Handler', () => {
     const signMpcRShareNockAwm = nock(advancedWalletManagerUrl)
       .post(`/api/${coin}/mpc/sign/r`)
       .reply(200, {
-        rShare: {
-          rShares: [
-            { r: 'r-share', R: 'R-share' },
-            { r: 'r-share-2', R: 'R-share-2' },
-            { r: 'r-share-3', R: 'R-share-3' },
-            { r: 'r-share-4', R: 'R-share-4', i: 3, j: 1 },
-          ],
-        },
+        rShare: { i: 3, j: 1, r: 'r-share', R: 'R-share', commitment: 'commitment' },
       });
 
     // Mock MPC G-share signing
     const signMpcGShareNockAwm = nock(advancedWalletManagerUrl)
-      .post(`/api/${coin}/mpc/sign/g`)
+      .post(`/api/${coin}/mpc/sign/g`, (body) => {
+        return (
+          body.encryptedUserToBitgoRShare?.share === 'encrypted-user-to-bitgo-r-share' &&
+          body.encryptedDataKey === 'test-encrypted-data-key' &&
+          body.userToBitgoRShare === undefined
+        );
+      })
       .reply(200, {
         gShare: {
           r: 'r',

src/__tests__/api/master/sendMany.test.ts

@@ -663,18 +663,17 @@ describe('POST /api/v1/:coin/advancedwallet/:walletId/sendMany', () => {
       const signMpcRShareNockAwm = nock(advancedWalletManagerUrl)
         .post(`/api/${coin}/mpc/sign/r`)
         .reply(200, {
-          rShare: {
-            rShares: [
-              { r: 'r-share', R: 'R-share' },
-              { r: 'r-share-2', R: 'R-share-2' },
-              { r: 'r-share-3', R: 'R-share-3' },
-              { r: 'r-share-4', R: 'R-share-4', i: 3, j: 1 },
-            ],
-          },
+          rShare: { i: 3, j: 1, r: 'r-share', R: 'R-share', commitment: 'commitment' },
         });
 
       const signMpcGShareNockAwm = nock(advancedWalletManagerUrl)
-        .post(`/api/${coin}/mpc/sign/g`)
+        .post(`/api/${coin}/mpc/sign/g`, (body) => {
+          return (
+            body.encryptedUserToBitgoRShare?.share === 'encrypted-user-to-bitgo-r-share' &&
+            body.encryptedDataKey === 'test-encrypted-data-key' &&
+            body.userToBitgoRShare === undefined
+          );
+        })
         .reply(200, {
           gShare: { r: 'r', gamma: 'gamma', i: 1, j: 3, n: 4 },
         });

src/__tests__/api/master/signAndSendTxRequest.test.ts

@@ -294,18 +294,17 @@ describe('POST /api/v1/:coin/advancedwallet/:walletId/txrequest/:txRequestId/sig
       const signMpcRShareNockAwm = nock(advancedWalletManagerUrl)
         .post(`/api/${eddsaCoin}/mpc/sign/r`)
         .reply(200, {
-          rShare: {
-            rShares: [
-              { r: 'r-share', R: 'R-share' },
-              { r: 'r-share-2', R: 'R-share-2' },
-              { r: 'r-share-3', R: 'R-share-3' },
-              { r: 'r-share-4', R: 'R-share-4', i: 3, j: 1 },
-            ],
-          },
+          rShare: { i: 3, j: 1, r: 'r-share', R: 'R-share', commitment: 'commitment' },
         });
 
       const signMpcGShareNockAwm = nock(advancedWalletManagerUrl)
-        .post(`/api/${eddsaCoin}/mpc/sign/g`)
+        .post(`/api/${eddsaCoin}/mpc/sign/g`, (body) => {
+          return (
+            body.encryptedUserToBitgoRShare?.share === 'encrypted-user-to-bitgo-r-share' &&
+            body.encryptedDataKey === 'test-encrypted-data-key' &&
+            body.userToBitgoRShare === undefined
+          );
+        })
         .reply(200, { gShare: { r: 'r', gamma: 'gamma', i: 1, j: 3, n: 4 } });
 
       const response = await agent

src/advancedWalletManager/handlers/ecdsaEddsaSignTransaction.ts

@@ -1,4 +1,7 @@
-import { AwmApiSpecRouteRequest } from '../routers/advancedWalletManagerApiSpec';
+import {
+  AwmApiSpecRouteRequest,
+  EddsaUserToBitgoRShare,
+} from '../routers/advancedWalletManagerApiSpec';
 import { decryptDataKey, generateDataKey, retrieveKeyProviderPrvKey } from './utils/utils';
 import logger from '../../shared/logger';
 import {
@@ -8,6 +11,7 @@ import {
   EddsaUtils,
   EncryptedSignerShareRecord,
   GShare,
+  ShareKeyPosition,
   SignatureShareRecord,
   SignShare,
   TxRequest,
@@ -67,7 +71,6 @@ interface EddsaSigningParams {
   prv: string;
   encryptedDataKey?: string;
   bitgoToUserRShare?: SignatureShareRecord;
-  userToBitgoRShare?: SignShare;
   encryptedUserToBitgoRShare?: EncryptedSignerShareRecord;
   bitgoToUserCommitment?: CommitmentShareRecord;
   bitgoPublicGpgKey?: string;
@@ -112,7 +115,6 @@ export async function signMpcTransaction(req: AwmApiSpecRouteRequest<'v1.mpc.sig
         prv,
         encryptedDataKey,
         bitgoToUserRShare: req.decoded.bitgoToUserRShare,
-        userToBitgoRShare: req.decoded.userToBitgoRShare,
         encryptedUserToBitgoRShare: req.decoded.encryptedUserToBitgoRShare,
         bitgoToUserCommitment: req.decoded.bitgoToUserCommitment,
         bitgoPublicGpgKey: req.decoded.bitgoPublicGpgKey,
@@ -146,7 +148,7 @@ async function handleEddsaSigning(
   userToBitgoCommitment?: CommitmentShareRecord;
   encryptedSignerShare?: EncryptedSignerShareRecord;
   encryptedUserToBitgoRShare?: EncryptedSignerShareRecord;
-  rShare?: SignShare;
+  rShare?: EddsaUserToBitgoRShare;
   gShare?: GShare;
   encryptedDataKey?: string;
 }> {
@@ -157,7 +159,6 @@ async function handleEddsaSigning(
     prv,
     encryptedDataKey,
     bitgoToUserRShare,
-    userToBitgoRShare,
     encryptedUserToBitgoRShare,
     bitgoToUserCommitment,
     bitgoPublicGpgKey,
@@ -184,32 +185,32 @@ async function handleEddsaSigning(
       };
     }
     case ShareType.R: {
-      if (!encryptedUserToBitgoRShare) {
-        throw new Error('encryptedUserToBitgoRShare is required for R share generation');
-      }
-      if (!encryptedDataKey) {
-        throw new Error(
-          'encryptedDataKey from commitment share generation round is required for R share generation',
-        );
-      }
-      const plaintextDataKey = await decryptDataKey({ encryptedDataKey, cfg });
-      const rShareParams: RShareParams = {
+      const userSignShare = await decryptUserSignShare(eddsaUtils, cfg, {
+        shareType: ShareType.R,
         txRequest,
-        walletPassphrase: plaintextDataKey,
+        encryptedDataKey,
         encryptedUserToBitgoRShare,
-      };
-      return await eddsaUtils.createRShareFromTxRequest(rShareParams);
+      });
+      const rShare = userSignShare.rShares[ShareKeyPosition.BITGO];
+      if (!rShare) {
+        throw new Error('Unable to find userToBitgo rShare in userSignShare');
+      }
+      const { i, j, r, R, commitment } = rShare;
+      return { rShare: { i, j, r, R, commitment } };
     }
     case ShareType.G: {
       if (!bitgoToUserRShare) {
         throw new Error('bitgoToUserRShare is required for G share generation');
       }
-      if (!userToBitgoRShare) {
-        throw new Error('userToBitgoRShare is required for G share generation');
-      }
       if (!bitgoToUserCommitment) {
         throw new Error('bitgoToUserCommitment is required for G share generation');
       }
+      const userToBitgoRShare = await decryptUserSignShare(eddsaUtils, cfg, {
+        shareType: ShareType.G,
+        txRequest,
+        encryptedDataKey,
+        encryptedUserToBitgoRShare,
+      });
       const gShareParams: GShareParams = {
         txRequest,
         prv,
@@ -227,6 +228,36 @@ async function handleEddsaSigning(
   }
 }
 
+async function decryptUserSignShare(
+  eddsaUtils: EddsaUtils,
+  cfg: AdvancedWalletManagerConfig,
+  params: {
+    shareType: ShareType;
+    txRequest: TxRequest;
+    encryptedDataKey?: string;
+    encryptedUserToBitgoRShare?: EncryptedSignerShareRecord;
+  },
+): Promise<SignShare> {
+  const { txRequest, encryptedDataKey, encryptedUserToBitgoRShare } = params;
+  const shareType = params.shareType.toUpperCase();
+  if (!encryptedUserToBitgoRShare) {
+    throw new Error(`encryptedUserToBitgoRShare is required for ${shareType} share generation`);
+  }
+  if (!encryptedDataKey) {
+    throw new Error(
+      `encryptedDataKey from commitment share generation round is required for ${shareType} share generation`,
+    );
+  }
+  const plaintextDataKey = await decryptDataKey({ encryptedDataKey, cfg });
+  const rShareParams: RShareParams = {
+    txRequest,
+    walletPassphrase: plaintextDataKey,
+    encryptedUserToBitgoRShare,
+  };
+  const { rShare } = await eddsaUtils.createRShareFromTxRequest(rShareParams);
+  return rShare;
+}
+
 async function handleEcdsaMpcV2Signing(
   bitgo: BitGoAPI,
   cfg: AdvancedWalletManagerConfig,

src/advancedWalletManager/routers/advancedWalletManagerApiSpec.ts

@@ -121,7 +121,6 @@ const SignMpcRequest = {
   pub: t.string,
   txRequest: t.any,
   bitgoToUserRShare: t.union([t.undefined, t.any]),
-  userToBitgoRShare: t.union([t.undefined, t.any]),
   encryptedUserToBitgoRShare: t.union([t.undefined, t.any]),
   bitgoToUserCommitment: t.union([t.undefined, t.any]),
   bitgoPublicGpgKey: t.union([t.undefined, t.string]),
@@ -133,6 +132,15 @@ const SignMpcRequest = {
   encryptedRound2Session: t.union([t.undefined, t.string]),
 };
 
+export const EddsaUserToBitgoRShare = t.type({
+  i: t.number,
+  j: t.number,
+  r: t.string,
+  R: t.string,
+  commitment: t.string,
+});
+export type EddsaUserToBitgoRShare = t.TypeOf<typeof EddsaUserToBitgoRShare>;
+
 // Response type for /mpc/sign endpoint
 const SignMpcResponse: HttpResponse = {
   // Response type for MPC transaction signing
@@ -146,7 +154,7 @@ const SignMpcResponse: HttpResponse = {
     }),
     // EDDSA R share response
     t.type({
-      rShare: t.any,
+      rShare: EddsaUserToBitgoRShare,
     }),
     // EDDSA G share response
     t.type({

src/masterBitgoExpress/clients/advancedWalletManagerClient.ts

@@ -14,7 +14,6 @@ import {
   MPCTxs,
   SignatureShareRecord,
   SignedTransaction,
-  SignShare,
   TransactionPrebuild,
   TxRequest,
 } from '@bitgo-beta/sdk-core';
@@ -32,6 +31,7 @@ import { AdvancedWalletManagerApiSpec } from '../../advancedWalletManager/router
 import { PingResponseType, VersionResponseType } from '../../types/health';
 import { extractTransactionRequestInfo } from '../../shared/transactionUtils';
 import {
+  EddsaUserToBitgoRShare,
   KeyShareType,
   MpcFinalizeResponseType,
   MpcInitializeResponseType,
@@ -123,22 +123,24 @@ export interface SignMpcCommitmentResponse {
   encryptedDataKey: string;
 }
 
-interface SignMpcRShareParams {
+type EddsaMpcCommitmentSigningState = Pick<
+  SignMpcCommitmentResponse,
+  'encryptedUserToBitgoRShare' | 'encryptedDataKey'
+>;
+
+interface SignMpcRShareParams extends EddsaMpcCommitmentSigningState {
   txRequest: TxRequest;
-  encryptedUserToBitgoRShare: EncryptedSignerShareRecord;
-  encryptedDataKey: string;
   source: 'user' | 'backup';
   pub: string;
 }
 
 interface SignMpcRShareResponse {
-  rShare: SignShare;
+  rShare: EddsaUserToBitgoRShare;
 }
 
-interface SignMpcGShareParams {
+interface SignMpcGShareParams extends EddsaMpcCommitmentSigningState {
   txRequest: TxRequest;
   bitgoToUserRShare: SignatureShareRecord;
-  userToBitgoRShare: SignShare;
   bitgoToUserCommitment: CommitmentShareRecord;
   source: 'user' | 'backup';
   pub: string;