feat(sdk-core): add EdDSA MPCv2 DSG helpers and DKG key-share util

- Add getEddsaSignatureShareRound{1,2,3} and verifyBitGoEddsaMessageRound{1,2}
  helpers in sdk-core for building/verifying PGP-signed MPS broadcast messages
- Parameterise partyId/otherSignerPartyId (defaults: user=0, bitgo=2) to
  support non-user signers without hardcoding
- Wire eddsaMpcV2 type in sendSignatureShareV2 (common.ts)
- Export helpers as EddsaMPCv2Utils from sdk-core public index
- Add generateEdDsaDKGKeyShares to sdk-lib-mpc MPSUtil (mirrors DklsUtils for ECDSA)
- Add unit tests covering all 5 helpers using io-ts decodeWithCodec for assertions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TICKET: WCI-153

Author: Marzooqa

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

@@ -131,6 +131,8 @@ export async function sendSignatureShareV2(
   let type = '';
   if (multisigTypeVersion === 'MPCv2' && mpcAlgorithm === 'ecdsa') {
     type = 'ecdsaMpcV2';
+  } else if (multisigTypeVersion === 'MPCv2' && mpcAlgorithm === 'eddsa') {
+    type = 'eddsaMpcV2';
   } else if (multisigTypeVersion === undefined && mpcAlgorithm === 'eddsa') {
     type = 'eddsaMpcV1';
   }

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

@@ -0,0 +1,126 @@
+import assert from 'assert';
+import * as openpgp from 'openpgp';
+import { MPSComms, MPSTypes } from '@bitgo/sdk-lib-mpc';
+import {
+  EddsaMPCv2SignatureShareRound1Input,
+  EddsaMPCv2SignatureShareRound1Output,
+  EddsaMPCv2SignatureShareRound2Input,
+  EddsaMPCv2SignatureShareRound2Output,
+  EddsaMPCv2SignatureShareRound3Input,
+} from '@bitgo/public-types';
+import { SignatureShareRecord, SignatureShareType } from '../../utils/tss/baseTypes';
+import { MPCv2PartiesEnum } from '../../utils/tss/ecdsa/typesMPCv2';
+
+function partyIdToSignatureShareType(partyId: 0 | 1 | 2): SignatureShareType {
+  assert(partyId === 0 || partyId === 1 || partyId === 2, 'Invalid partyId for EdDSA MPCv2 signing');
+  switch (partyId) {
+    case 0:
+      return SignatureShareType.USER;
+    case 1:
+      return SignatureShareType.BACKUP;
+    case 2:
+      return SignatureShareType.BITGO;
+  }
+}
+
+/**
+ * Builds the round-1 signature share record.
+ *
+ * PGP-signs the WASM round-0 broadcast message with the signer's ephemeral key and
+ * wraps it into a SignatureShareRecord ready for `sendSignatureShareV2`.
+ */
+export async function getEddsaSignatureShareRound1(
+  userMsg1: MPSTypes.DeserializedMessage,
+  userGpgPrivKey: openpgp.PrivateKey,
+  partyId: 0 | 1 = 0,
+  otherSignerPartyId: 0 | 1 | 2 = 2
+): Promise<SignatureShareRecord> {
+  const signedMsg1 = await MPSComms.detachSignMpsMessage(Buffer.from(userMsg1.payload), userGpgPrivKey);
+  const share: EddsaMPCv2SignatureShareRound1Input = {
+    type: 'round1Input',
+    data: { msg1: signedMsg1 },
+  };
+  return {
+    from: partyIdToSignatureShareType(partyId),
+    to: partyIdToSignatureShareType(otherSignerPartyId),
+    share: JSON.stringify(share),
+  };
+}
+
+/**
+ * Verifies the peer's round-1 PGP signature and returns the raw deserialized
+ * message ready for `DSG.handleIncomingMessages`.
+ */
+export async function verifyBitGoEddsaMessageRound1(
+  parsedRound1Output: EddsaMPCv2SignatureShareRound1Output,
+  bitgoGpgKey: openpgp.Key,
+  peerPartyId: 0 | 1 | 2 = 2
+): Promise<MPSTypes.DeserializedMessage> {
+  const rawBytes = await MPSComms.verifyMpsMessage(parsedRound1Output.data.msg1, bitgoGpgKey);
+  return {
+    from: peerPartyId as MPCv2PartiesEnum,
+    payload: new Uint8Array(rawBytes),
+  };
+}
+
+/**
+ * Builds the round-2 signature share record.
+ */
+export async function getEddsaSignatureShareRound2(
+  userMsg2: MPSTypes.DeserializedMessage,
+  userGpgPrivKey: openpgp.PrivateKey,
+  partyId: 0 | 1 = 0,
+  otherSignerPartyId: 0 | 1 | 2 = 2
+): Promise<SignatureShareRecord> {
+  const signedMsg2 = await MPSComms.detachSignMpsMessage(Buffer.from(userMsg2.payload), userGpgPrivKey);
+  const share: EddsaMPCv2SignatureShareRound2Input = {
+    type: 'round2Input',
+    data: { msg2: signedMsg2 },
+  };
+  return {
+    from: partyIdToSignatureShareType(partyId),
+    to: partyIdToSignatureShareType(otherSignerPartyId),
+    share: JSON.stringify(share),
+  };
+}
+
+/**
+ * Verifies the peer's round-2 PGP signature and returns the raw deserialized
+ * message ready for `DSG.handleIncomingMessages`.
+ */
+export async function verifyBitGoEddsaMessageRound2(
+  parsedRound2Output: EddsaMPCv2SignatureShareRound2Output,
+  bitgoGpgKey: openpgp.Key,
+  peerPartyId: 0 | 1 | 2 = 2
+): Promise<MPSTypes.DeserializedMessage> {
+  const rawBytes = await MPSComms.verifyMpsMessage(parsedRound2Output.data.msg2, bitgoGpgKey);
+  return {
+    from: peerPartyId as MPCv2PartiesEnum,
+    payload: new Uint8Array(rawBytes),
+  };
+}
+
+/**
+ * Builds the round-3 signature share record (final signer message).
+ *
+ * There is no corresponding `verifyBitGoEddsaMessageRound3` because Wallet Platform
+ * finalises the signing server-side after receiving round 3; the client obtains the
+ * signed transaction via `sendTxRequest`.
+ */
+export async function getEddsaSignatureShareRound3(
+  userMsg3: MPSTypes.DeserializedMessage,
+  userGpgPrivKey: openpgp.PrivateKey,
+  partyId: 0 | 1 = 0,
+  otherSignerPartyId: 0 | 1 | 2 = 2
+): Promise<SignatureShareRecord> {
+  const signedMsg3 = await MPSComms.detachSignMpsMessage(Buffer.from(userMsg3.payload), userGpgPrivKey);
+  const share: EddsaMPCv2SignatureShareRound3Input = {
+    type: 'round3Input',
+    data: { msg3: signedMsg3 },
+  };
+  return {
+    from: partyIdToSignatureShareType(partyId),
+    to: partyIdToSignatureShareType(otherSignerPartyId),
+    share: JSON.stringify(share),
+  };
+}

modules/sdk-core/src/index.ts

@@ -10,6 +10,8 @@ import { EcdsaUtils } from './bitgo/utils/tss/ecdsa/ecdsa';
 export { EcdsaUtils };
 import { EcdsaMPCv2Utils } from './bitgo/utils/tss/ecdsa/ecdsaMPCv2';
 export { EcdsaMPCv2Utils };
+import { EddsaMPCv2Utils } from './bitgo/utils/tss/eddsa/eddsaMPCv2';
+export { EddsaMPCv2Utils };
 export { verifyEddsaTssWalletAddress, verifyMPCWalletAddress } from './bitgo/utils/tss/addressVerification';
 export { GShare, SignShare, YShare } from './account-lib/mpc/tss/eddsa/types';
 export { TssEcdsaStep1ReturnMessage, TssEcdsaStep2ReturnMessage } from './bitgo/tss/types';

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

@@ -0,0 +1,206 @@
+import * as assert from 'assert';
+import * as pgp from 'openpgp';
+import { EddsaMPSDsg, MPSComms, MPSUtil } from '@bitgo/sdk-lib-mpc';
+import {
+  EddsaMPCv2SignatureShareRound1Input,
+  EddsaMPCv2SignatureShareRound1Output,
+  EddsaMPCv2SignatureShareRound2Input,
+  EddsaMPCv2SignatureShareRound2Output,
+  EddsaMPCv2SignatureShareRound3Input,
+} from '@bitgo/public-types';
+import { SignatureShareRecord, SignatureShareType } from '../../../../../../src';
+import {
+  getEddsaSignatureShareRound1,
+  getEddsaSignatureShareRound2,
+  getEddsaSignatureShareRound3,
+  verifyBitGoEddsaMessageRound1,
+  verifyBitGoEddsaMessageRound2,
+} from '../../../../../../src/bitgo/tss/eddsa/eddsaMPCv2';
+import { decodeWithCodec } from '../../../../../../src/bitgo/utils/codecs';
+import { generateGPGKeyPair } from '../../../../../../src/bitgo/utils/opengpgUtils';
+import { MPCv2PartiesEnum } from '../../../../../../src/bitgo/utils/tss/ecdsa/typesMPCv2';
+
+describe('EdDSA MPS DSG helper functions', async () => {
+  let userKeyShare: Buffer;
+  let bitgoKeyShare: Buffer;
+  let userGpgPrivKey: pgp.PrivateKey;
+  let bitgoGpgPrivKey: pgp.PrivateKey;
+  let bitgoGpgPubKey: pgp.Key;
+
+  const signableHex = 'deadbeef';
+  const derivationPath = 'm/0';
+
+  before('generate EdDSA DKG key shares', async () => {
+    const userGpgKeyPair = await generateGPGKeyPair('ed25519');
+    const bitgoGpgKeyPair = await generateGPGKeyPair('ed25519');
+
+    userGpgPrivKey = await pgp.readPrivateKey({ armoredKey: userGpgKeyPair.privateKey });
+    bitgoGpgPrivKey = await pgp.readPrivateKey({ armoredKey: bitgoGpgKeyPair.privateKey });
+    bitgoGpgPubKey = await pgp.readKey({ armoredKey: bitgoGpgKeyPair.publicKey });
+
+    const [userDkg, , bitgoDkg] = await MPSUtil.generateEdDsaDKGKeyShares();
+    userKeyShare = userDkg.getKeyShare();
+    bitgoKeyShare = bitgoDkg.getKeyShare();
+  });
+
+  // ── Round 1 ─────────────────────────────────────────────────────────────────
+
+  it('getEddsaSignatureShareRound1 should build a valid round-1 share', async () => {
+    const messageBuffer = Buffer.from(signableHex, 'hex');
+    const userDsg = new EddsaMPSDsg.DSG(MPCv2PartiesEnum.USER);
+    userDsg.initDsg(userKeyShare, messageBuffer, derivationPath, MPCv2PartiesEnum.BITGO);
+    const userMsg1 = userDsg.getFirstMessage();
+
+    const share: SignatureShareRecord = await getEddsaSignatureShareRound1(userMsg1, userGpgPrivKey);
+
+    assert.strictEqual(share.from, SignatureShareType.USER);
+    assert.strictEqual(share.to, SignatureShareType.BITGO);
+
+    const parsed = decodeWithCodec(
+      EddsaMPCv2SignatureShareRound1Input,
+      JSON.parse(share.share),
+      'EddsaMPCv2SignatureShareRound1Input'
+    );
+    assert.strictEqual(parsed.type, 'round1Input');
+    assert.ok(parsed.data.msg1.message, 'msg1.message should be set');
+    assert.ok(parsed.data.msg1.signature, 'msg1.signature should be set');
+  });
+
+  it('verifyBitGoEddsaMessageRound1 should verify a valid BitGo round-1 message', async () => {
+    const messageBuffer = Buffer.from(signableHex, 'hex');
+    const bitgoDsg = new EddsaMPSDsg.DSG(MPCv2PartiesEnum.BITGO);
+    bitgoDsg.initDsg(bitgoKeyShare, messageBuffer, derivationPath, MPCv2PartiesEnum.USER);
+    const bitgoMsg1 = bitgoDsg.getFirstMessage();
+
+    const bitgoSignedMsg1 = await MPSComms.detachSignMpsMessage(Buffer.from(bitgoMsg1.payload), bitgoGpgPrivKey);
+    const round1Output: EddsaMPCv2SignatureShareRound1Output = {
+      type: 'round1Output',
+      data: { msg1: bitgoSignedMsg1 },
+    };
+
+    const result = await verifyBitGoEddsaMessageRound1(round1Output, bitgoGpgPubKey);
+
+    assert.strictEqual(result.from, MPCv2PartiesEnum.BITGO);
+    assert.ok(result.payload.length > 0, 'payload should be non-empty');
+  });
+
+  it('verifyBitGoEddsaMessageRound1 should throw on a tampered message', async () => {
+    const round1Output: EddsaMPCv2SignatureShareRound1Output = {
+      type: 'round1Output',
+      data: {
+        msg1: {
+          message: Buffer.from('tampered').toString('base64'),
+          signature: '-----BEGIN PGP SIGNATURE-----\n\nINVALID\n-----END PGP SIGNATURE-----\n',
+        },
+      },
+    };
+
+    await assert.rejects(
+      verifyBitGoEddsaMessageRound1(round1Output, bitgoGpgPubKey),
+      'should throw on invalid signature'
+    );
+  });
+
+  // ── Round 2 ─────────────────────────────────────────────────────────────────
+
+  it('getEddsaSignatureShareRound2 should build a valid round-2 share', async () => {
+    const messageBuffer = Buffer.from(signableHex, 'hex');
+    const userDsg = new EddsaMPSDsg.DSG(MPCv2PartiesEnum.USER);
+    userDsg.initDsg(userKeyShare, messageBuffer, derivationPath, MPCv2PartiesEnum.BITGO);
+    const userMsg1 = userDsg.getFirstMessage();
+
+    const bitgoDsg = new EddsaMPSDsg.DSG(MPCv2PartiesEnum.BITGO);
+    bitgoDsg.initDsg(bitgoKeyShare, messageBuffer, derivationPath, MPCv2PartiesEnum.USER);
+    const bitgoMsg1 = bitgoDsg.getFirstMessage();
+
+    const bitgoSignedMsg1 = await MPSComms.detachSignMpsMessage(Buffer.from(bitgoMsg1.payload), bitgoGpgPrivKey);
+    const bitgoDeserializedMsg1 = await verifyBitGoEddsaMessageRound1(
+      { type: 'round1Output', data: { msg1: bitgoSignedMsg1 } },
+      bitgoGpgPubKey
+    );
+    const [userMsg2] = userDsg.handleIncomingMessages([userMsg1, bitgoDeserializedMsg1]);
+
+    const share: SignatureShareRecord = await getEddsaSignatureShareRound2(userMsg2, userGpgPrivKey);
+
+    assert.strictEqual(share.from, SignatureShareType.USER);
+    assert.strictEqual(share.to, SignatureShareType.BITGO);
+
+    const parsed = decodeWithCodec(
+      EddsaMPCv2SignatureShareRound2Input,
+      JSON.parse(share.share),
+      'EddsaMPCv2SignatureShareRound2Input'
+    );
+    assert.strictEqual(parsed.type, 'round2Input');
+    assert.ok(parsed.data.msg2.message, 'msg2.message should be set');
+    assert.ok(parsed.data.msg2.signature, 'msg2.signature should be set');
+  });
+
+  it('verifyBitGoEddsaMessageRound2 should verify a valid BitGo round-2 message', async () => {
+    const messageBuffer = Buffer.from(signableHex, 'hex');
+    const userDsg = new EddsaMPSDsg.DSG(MPCv2PartiesEnum.USER);
+    userDsg.initDsg(userKeyShare, messageBuffer, derivationPath, MPCv2PartiesEnum.BITGO);
+    const userMsg1 = userDsg.getFirstMessage();
+
+    const bitgoDsg = new EddsaMPSDsg.DSG(MPCv2PartiesEnum.BITGO);
+    bitgoDsg.initDsg(bitgoKeyShare, messageBuffer, derivationPath, MPCv2PartiesEnum.USER);
+    const bitgoMsg1 = bitgoDsg.getFirstMessage();
+
+    const bitgoSignedMsg1 = await MPSComms.detachSignMpsMessage(Buffer.from(bitgoMsg1.payload), bitgoGpgPrivKey);
+    const [bitgoMsg2] = bitgoDsg.handleIncomingMessages([bitgoMsg1, userMsg1]);
+    const bitgoSignedMsg2 = await MPSComms.detachSignMpsMessage(Buffer.from(bitgoMsg2.payload), bitgoGpgPrivKey);
+
+    const round2Output: EddsaMPCv2SignatureShareRound2Output = {
+      type: 'round2Output',
+      data: { msg2: bitgoSignedMsg2 },
+    };
+
+    void bitgoSignedMsg1;
+    const result = await verifyBitGoEddsaMessageRound2(round2Output, bitgoGpgPubKey);
+
+    assert.strictEqual(result.from, MPCv2PartiesEnum.BITGO);
+    assert.ok(result.payload.length > 0, 'payload should be non-empty');
+  });
+
+  // ── Round 3 ─────────────────────────────────────────────────────────────────
+
+  it('getEddsaSignatureShareRound3 should build a valid round-3 share', async () => {
+    const messageBuffer = Buffer.from(signableHex, 'hex');
+    const userDsg = new EddsaMPSDsg.DSG(MPCv2PartiesEnum.USER);
+    userDsg.initDsg(userKeyShare, messageBuffer, derivationPath, MPCv2PartiesEnum.BITGO);
+    const userMsg1 = userDsg.getFirstMessage();
+
+    const bitgoDsg = new EddsaMPSDsg.DSG(MPCv2PartiesEnum.BITGO);
+    bitgoDsg.initDsg(bitgoKeyShare, messageBuffer, derivationPath, MPCv2PartiesEnum.USER);
+    const bitgoMsg1 = bitgoDsg.getFirstMessage();
+
+    // Advance to round 2
+    const bitgoSignedMsg1 = await MPSComms.detachSignMpsMessage(Buffer.from(bitgoMsg1.payload), bitgoGpgPrivKey);
+    const bitgoDeserializedMsg1 = await verifyBitGoEddsaMessageRound1(
+      { type: 'round1Output', data: { msg1: bitgoSignedMsg1 } },
+      bitgoGpgPubKey
+    );
+    const [userMsg2] = userDsg.handleIncomingMessages([userMsg1, bitgoDeserializedMsg1]);
+
+    const [bitgoMsg2] = bitgoDsg.handleIncomingMessages([bitgoMsg1, userMsg1]);
+    const bitgoSignedMsg2 = await MPSComms.detachSignMpsMessage(Buffer.from(bitgoMsg2.payload), bitgoGpgPrivKey);
+    const bitgoDeserializedMsg2 = await verifyBitGoEddsaMessageRound2(
+      { type: 'round2Output', data: { msg2: bitgoSignedMsg2 } },
+      bitgoGpgPubKey
+    );
+    const [userMsg3] = userDsg.handleIncomingMessages([userMsg2, bitgoDeserializedMsg2]);
+
+    const share: SignatureShareRecord = await getEddsaSignatureShareRound3(userMsg3, userGpgPrivKey);
+
+    assert.strictEqual(share.from, SignatureShareType.USER);
+    assert.strictEqual(share.to, SignatureShareType.BITGO);
+
+    const parsed = decodeWithCodec(
+      EddsaMPCv2SignatureShareRound3Input,
+      JSON.parse(share.share),
+      'EddsaMPCv2SignatureShareRound3Input'
+    );
+    assert.strictEqual(parsed.type, 'round3Input');
+    assert.ok(parsed.data.msg3.message, 'msg3.message should be set');
+    assert.ok(parsed.data.msg3.signature, 'msg3.signature should be set');
+  });
+});