feat(sdk-api): gpg passkey authentication

add gpg decryption and signature verification to passkey authentication

TICKET: WP-2733

Author: Alvin Dai

modules/bitgo/test/unit/bitgo.ts

@@ -5,8 +5,9 @@
 import * as crypto from 'crypto';
 import * as nock from 'nock';
 import * as should from 'should';
+import assert = require('assert');
 
-import { common } from '@bitgo/sdk-core';
+import { common, generateGPGKeyPair, encryptAndSignText } from '@bitgo/sdk-core';
 import { bip32, ECPair } from '@bitgo/utxo-lib';
 import * as _ from 'lodash';
 import * as BitGoJS from '../../src/index';
@@ -687,4 +688,117 @@ describe('BitGo Prototype Methods', function () {
       response.user.ecdhKeychain.should.equal('some-xpub');
     });
   });
+
+  describe('passkey authentication', () => {
+    afterEach(function ensureNoPendingMocks() {
+      nock.cleanAll();
+      nock.pendingMocks().should.be.empty();
+    });
+
+    it('should authenticate with a passkey', async () => {
+      const userId = '123';
+      const passkey = `{"id": "id", "response": {"authenticatorData": "123", "clientDataJSON": "123", "signature": "123", "userHandle": "${userId}"}}`;
+      const keyPair = await generateGPGKeyPair('secp256k1');
+
+      nock('https://bitgo.fakeurl')
+        .persist()
+        .get('/api/v1/client/constants')
+        .reply(200, { ttl: 3600, constants: { passkeyBitGoGpgKey: keyPair.publicKey } });
+
+      nock('https://bitgo.fakeurl')
+        .post('/api/auth/v1/session')
+        .reply(200, async (uri, requestBody) => {
+          assert(typeof requestBody === 'object');
+          should.exist(requestBody.publicKey);
+          should.exist(requestBody.userId);
+          should.exist(requestBody.passkey);
+          requestBody.userId.should.equal(userId);
+          requestBody.passkey.should.equal(passkey);
+          const encryptedToken = (await encryptAndSignText(
+            'access_token',
+            requestBody.publicKey,
+            keyPair.privateKey
+          )) as string;
+
+          return {
+            encryptedToken: encryptedToken,
+            user: { username: '[email protected]' },
+          };
+        });
+
+      const bitgo = TestBitGo.decorate(BitGo, { env: 'mock' });
+      const response = await bitgo.authenticateWithPasskey(passkey);
+      should.exist(response.access_token);
+      response.access_token.should.equal('access_token');
+    });
+
+    it('should not authenticate with wrong encryption key', async () => {
+      const keyPair = await generateGPGKeyPair('secp256k1');
+
+      nock('https://bitgo.fakeurl')
+        .persist()
+        .get('/api/v1/client/constants')
+        .reply(200, { ttl: 3600, constants: { passkeyBitGoGpgKey: keyPair.publicKey } });
+      nock('https://bitgo.fakeurl')
+        .post('/api/auth/v1/session')
+        .reply(200, async () => {
+          const keyPair = await generateGPGKeyPair('secp256k1');
+          const encryptedToken = (await encryptAndSignText(
+            'access_token',
+            keyPair.publicKey,
+            keyPair.privateKey
+          )) as string;
+          return {
+            encryptedToken: encryptedToken,
+            user: { username: '[email protected]' },
+          };
+        });
+
+      const bitgo = TestBitGo.decorate(BitGo, { env: 'mock' });
+      try {
+        await bitgo.authenticateWithPasskey(
+          '{"id": "id", "response": {"authenticatorData": "123", "clientDataJSON": "123", "signature": "123", "userHandle": "123"}}'
+        );
+        assert.fail('Expected error not thrown');
+      } catch (e) {
+        assert.equal(e.message, 'Error decrypting message: Session key decryption failed.');
+      }
+    });
+
+    it('should not authenticate with wrong signing key', async () => {
+      const userId = '123';
+      const passkey = `{"id": "id", "response": {"authenticatorData": "123", "clientDataJSON": "123", "signature": "123", "userHandle": "${userId}"}}`;
+      const badKeyPair = await generateGPGKeyPair('secp256k1');
+      const bitgoKeyPair = await generateGPGKeyPair('secp256k1');
+
+      nock('https://bitgo.fakeurl')
+        .persist()
+        .get('/api/v1/client/constants')
+        .reply(200, { ttl: 3600, constants: { passkeyBitGoGpgKey: bitgoKeyPair.publicKey } });
+
+      nock('https://bitgo.fakeurl')
+        .post('/api/auth/v1/session')
+        .reply(200, async (uri, requestBody) => {
+          assert(typeof requestBody === 'object');
+          const encryptedToken = (await encryptAndSignText(
+            'access_token',
+            requestBody.publicKey,
+            badKeyPair.privateKey
+          )) as string;
+
+          return {
+            encryptedToken: encryptedToken,
+            user: { username: '[email protected]' },
+          };
+        });
+
+      const bitgo = TestBitGo.decorate(BitGo, { env: 'mock' });
+      try {
+        await bitgo.authenticateWithPasskey(passkey);
+        assert.fail('Expected error not thrown');
+      } catch (e) {
+        assert(e.message.startsWith('Error decrypting message: Could not find signing key with key ID'));
+      }
+    });
+  });
 });

modules/sdk-api/src/bitgoAPI.ts

@@ -20,6 +20,8 @@ import {
   IRequestTracer,
   makeRandomKey,
   sanitizeLegacyPath,
+  generateGPGKeyPair,
+  readSignedMessage,
 } from '@bitgo/sdk-core';
 import * as sjcl from '@bitgo/sjcl';
 import * as utxolib from '@bitgo/utxo-lib';
@@ -956,20 +958,33 @@ export class BitGoAPI implements BitGoBase {
       this.validatePasskeyResponse(passkey);
       const userId = JSON.parse(passkey).response.userHandle;
 
+      const userGpgKey = await generateGPGKeyPair('secp256k1');
       const response: superagent.Response = await request.send({
         passkey: passkey,
         userId: userId,
+        publicKey: userGpgKey.publicKey,
       });
       // extract body and user information
       const body = response.body;
       this._user = body.user;
 
-      // Expecting unencrypted access token in response for now
-      // TODO (WP-2733): Use GPG encryption to decrypt access token
       if (body.access_token) {
         this._token = body.access_token;
+      } else if (body.encryptedToken) {
+        const constants = await this.fetchConstants();
+
+        if (!constants.passkeyBitGoGpgKey) {
+          throw new Error('passkeyBitGoGpgKey is missing from constants');
+        }
+
+        const access_token = await readSignedMessage(
+          body.encryptedToken,
+          constants.passkeyBitGoGpgKey,
+          userGpgKey.privateKey
+        );
+        response.body.access_token = access_token;
       } else {
-        throw new Error('failed to create access token');
+        throw new Error('Failed to login. Please contact [email protected]');
       }
 
       return handleResponseResult<LoginResponse>()(response);