Merge pull request #58 from ethereumjs/rpcsig-padding

Pad rpcSig output

index.js

@@ -391,9 +391,18 @@ exports.ecrecover = function (msgHash, v, r, s) {
  * @return {String} sig
  */
 exports.toRpcSig = function (v, r, s) {
+  // NOTE: with potential introduction of chainId this might need to be updated
+  if (v !== 27 && v !== 28) {
+    throw new Error('Invalid recovery id')
+  }
+
   // geth (and the RPC eth_sign method) uses the 65 byte format used by Bitcoin
   // FIXME: this might change in the future - https://github.com/ethereum/go-ethereum/issues/2053
-  return exports.bufferToHex(Buffer.concat([ r, s, exports.toBuffer(v - 27) ]))
+  return exports.bufferToHex(Buffer.concat([
+    exports.setLengthLeft(r, 32),
+    exports.setLengthLeft(s, 32),
+    exports.toBuffer(v - 27)
+  ]))
 }
 
 /**
@@ -405,6 +414,7 @@ exports.toRpcSig = function (v, r, s) {
 exports.fromRpcSig = function (sig) {
   sig = exports.toBuffer(sig)
 
+  // NOTE: with potential introduction of chainId this might need to be updated
   if (sig.length !== 65) {
     throw new Error('Invalid signature length')
   }

test/index.js

@@ -578,4 +578,14 @@ describe('message sig', function () {
       ethUtils.fromRpcSig('0x99e71a99cb2270b8cac5254f9e99b6210c6c10224a1579cf389ef88b20a1abe9129ff05af364204442bdb53ab6f18a99ab48acc9326fa689f228040429e3ca660042')
     })
   })
+
+  it('pad short r and s values', function () {
+    assert.equal(ethUtils.toRpcSig(27, r.slice(20), s.slice(20)), '0x00000000000000000000000000000000000000004a1579cf389ef88b20a1abe90000000000000000000000000000000000000000326fa689f228040429e3ca6600')
+  })
+
+  it('should throw on invalid v value', function () {
+    assert.throws(function () {
+      ethUtils.toRpcSig(1, r, s)
+    })
+  })
 })