feat(express): take walletPassphrase as body parameter for /api/v2/ofc/signPayload

Ticket: GNA-1383

Author: jzhao-bitgo

modules/express/EXTERNAL_SIGNER.md

@@ -60,9 +60,14 @@ An example is provided in the file. To run the file, use the command:
 yarn ts-node <path/to/fetchEncryptedPrivKeys.ts>
 ```
 
-### Wallet passphrase environment variable
+### Wallet passphrase
+In order for the external signer instance of BitGo Express to decrypt the private key, the wallet passphrase is required. This can be supplied by one of the below methods.
 
-In order for the external signer instance of BitGo Express to decrypt the private key, the wallet passphrase must be set as an environment variable in the format `WALLET_<walletId>_PASSPHRASE`. Note that the wallet passphrase must be set for each wallet.
+#### Sending as a body parameter (recommended)
+Set the parameter `walletPassphrase: <YOUR_WALLET_PASSPHRASE>` (without <>) in POST requests to the endpoint `/api/v2/ofc/signPayload`.
+
+#### Set as environment variable
+Set as an environment variable in the format `WALLET_<walletId>_PASSPHRASE`. Note that the wallet passphrase must be set for each wallet.
 The environment variable can be set using `export`. For example, the wallet passphrases for the private keys above can be set with the following:
 
 ```

modules/express/src/clientRoutes.ts

@@ -546,6 +546,7 @@ export async function handleV2OFCSignPayloadInExtSigningMode(
 ): Promise<{ payload: string; signature: string }> {
   const walletId = req.body.walletId;
   const payload = req.body.payload;
+  const bodyWalletPassphrase = req.body.walletPassphrase;
   const ofcCoinName = 'ofc';
 
   if (!payload) {
@@ -556,8 +557,8 @@ export async function handleV2OFCSignPayloadInExtSigningMode(
     throw new ApiResponseError('Missing required field: walletId', 400);
   }
 
-  // fetch the password for the given walletId from the env. This is required for decrypting the private key that belongs to that wallet.
-  const walletPw = getWalletPwFromEnv(walletId);
+  // fetch the password for the given walletId from the body or the env. This is required for decrypting the private key that belongs to that wallet.
+  const walletPw = bodyWalletPassphrase || getWalletPwFromEnv(walletId);
 
   const { signerFileSystemPath } = req.config;
   if (!signerFileSystemPath) {
@@ -593,6 +594,7 @@ export async function handleV2OFCSignPayloadInExtSigningMode(
 export async function handleV2OFCSignPayload(req: express.Request): Promise<{ payload: string; signature: string }> {
   const walletId = req.body.walletId;
   const payload = req.body.payload;
+  const bodyWalletPassphrase = req.body.walletPassphrase;
   const ofcCoinName = 'ofc';
 
   // If the externalSignerUrl is set, forward the request to the express server hosted on the externalSignerUrl
@@ -628,7 +630,7 @@ export async function handleV2OFCSignPayload(req: express.Request): Promise<{ pa
     throw new ApiResponseError(`Could not find OFC wallet ${walletId}`, 404);
   }
 
-  const walletPassphrase = getWalletPwFromEnv(wallet.id());
+  const walletPassphrase = bodyWalletPassphrase || getWalletPwFromEnv(wallet.id());
   const tradingAccount = wallet.toTradingAccount();
   const stringifiedPayload = JSON.stringify(req.body.payload);
   const signature = await tradingAccount.signPayload({

modules/express/test/unit/clientRoutes/signPayload.ts

@@ -116,6 +116,82 @@ describe('With the handler to sign an arbitrary payload in external signing mode
     );
     readFileStub.restore();
     envStub.restore();
+    signMessageStub.restore();
+  });
+
+  it('should use wallet passphrase from request body', async () => {
+    const stubbedSignature = Buffer.from('mysign');
+    const readFileStub = sinon.stub(fs.promises, 'readFile').resolves(validPrv);
+
+    const signMessageStub = sinon.stub(Coin.Ofc.prototype, 'signMessage').resolves(stubbedSignature);
+
+    const stubbedSigHex = stubbedSignature.toString('hex');
+
+    const expectedResponse = {
+      payload: JSON.stringify(payload),
+      signature: stubbedSigHex,
+    };
+
+    const req = {
+      bitgo,
+      body: {
+        walletId,
+        payload,
+        walletPassphrase: walletPassword,
+      },
+      config: {
+        signerFileSystemPath: 'signerFileSystemPath',
+      },
+    } as unknown as Request;
+
+    await handleV2OFCSignPayloadInExtSigningMode(req).should.be.resolvedWith(expectedResponse);
+    readFileStub.should.be.calledOnceWith('signerFileSystemPath');
+    signMessageStub.should.be.calledOnceWith(
+      sinon.match({
+        prv: secret,
+      })
+    );
+    readFileStub.restore();
+    signMessageStub.restore();
+  });
+
+  it('should prioritize request body passphrase over environment variable', async () => {
+    const stubbedSignature = Buffer.from('mysign');
+    const readFileStub = sinon.stub(fs.promises, 'readFile').resolves(validPrv);
+    const envStub = sinon
+      .stub(process, 'env')
+      .value({ WALLET_61f039aad587c2000745c687373e0fa9_PASSPHRASE: walletPassword });
+
+    const signMessageStub = sinon.stub(Coin.Ofc.prototype, 'signMessage').resolves(stubbedSignature);
+
+    const stubbedSigHex = stubbedSignature.toString('hex');
+
+    const expectedResponse = {
+      payload: JSON.stringify(payload),
+      signature: stubbedSigHex,
+    };
+    const req = {
+      bitgo,
+      body: {
+        walletId,
+        payload,
+        walletPassphrase: walletPassword,
+      },
+      config: {
+        signerFileSystemPath: 'signerFileSystemPath',
+      },
+    } as unknown as Request;
+
+    await handleV2OFCSignPayloadInExtSigningMode(req).should.be.resolvedWith(expectedResponse);
+    readFileStub.should.be.calledOnceWith('signerFileSystemPath');
+    signMessageStub.should.be.calledOnceWith(
+      sinon.match({
+        prv: secret,
+      })
+    );
+    readFileStub.restore();
+    envStub.restore();
+    signMessageStub.restore();
   });
 
   describe('With invalid setup', () => {
@@ -206,5 +282,27 @@ describe('With the handler to sign an arbitrary payload in external signing mode
       readFileStub.restore();
       envStub.restore();
     });
+
+    it('should throw error when trying to decrypt with invalid wallet passphrase in body', async () => {
+      const readFileStub = sinon.stub(fs.promises, 'readFile').resolves(validPrv);
+
+      const req = {
+        bitgo,
+        body: {
+          walletId,
+          payload,
+          walletPassphrase: 'invalidPassphrase',
+        },
+        config: {
+          signerFileSystemPath: 'signerFileSystemPath',
+        },
+      } as unknown as Request;
+
+      await handleV2OFCSignPayloadInExtSigningMode(req).should.be.rejectedWith(
+        "Error when trying to decrypt private key: CORRUPT: password error - ccm: tag doesn't match"
+      );
+
+      readFileStub.restore();
+    });
   });
 });