ECSignature: add toRSBuffer/fromRSBuffer

Author: dcousens

src/ecsignature.js

@@ -12,24 +12,30 @@ function ECSignature (r, s) {
 }
 
 ECSignature.parseCompact = function (buffer) {
-  if (buffer.length !== 65) throw new Error('Invalid signature length')
+  typeforce(types.BufferN(65), buffer)
 
   var flagByte = buffer.readUInt8(0) - 27
   if (flagByte !== (flagByte & 7)) throw new Error('Invalid signature parameter')
 
   var compressed = !!(flagByte & 4)
   var recoveryParam = flagByte & 3
-
-  var r = BigInteger.fromBuffer(buffer.slice(1, 33))
-  var s = BigInteger.fromBuffer(buffer.slice(33))
+  var signature = ECSignature.fromRSBuffer(buffer.slice(1))
 
   return {
     compressed: compressed,
     i: recoveryParam,
-    signature: new ECSignature(r, s)
+    signature: signature
   }
 }
 
+ECSignature.fromRSBuffer = function (buffer) {
+  typeforce(types.BufferN(64), buffer)
+
+  var r = BigInteger.fromBuffer(buffer.slice(0, 32))
+  var s = BigInteger.fromBuffer(buffer.slice(32, 64))
+  return new ECSignature(r, s)
+}
+
 ECSignature.fromDER = function (buffer) {
   var decode = bip66.decode(buffer)
   var r = BigInteger.fromDERInteger(decode.r)
@@ -60,9 +66,7 @@ ECSignature.prototype.toCompact = function (i, compressed) {
 
   var buffer = Buffer.alloc(65)
   buffer.writeUInt8(i, 0)
-  this.r.toBuffer(32).copy(buffer, 1)
-  this.s.toBuffer(32).copy(buffer, 33)
-
+  this.toRSBuffer(buffer, 1)
   return buffer
 }
 
@@ -73,6 +77,13 @@ ECSignature.prototype.toDER = function () {
   return bip66.encode(r, s)
 }
 
+ECSignature.prototype.toRSBuffer = function (buffer, offset) {
+  buffer = buffer || Buffer.alloc(64)
+  this.r.toBuffer(32).copy(buffer, offset)
+  this.s.toBuffer(32).copy(buffer, offset + 32)
+  return buffer
+}
+
 ECSignature.prototype.toScriptSignature = function (hashType) {
   var hashTypeMod = hashType & ~0x80
   if (hashTypeMod <= 0 || hashTypeMod >= 4) throw new Error('Invalid hashType ' + hashType)

test/fixtures/ecsignature.json

@@ -120,11 +120,11 @@
         "hex": "23987ceade6a304fc5823ab38f99fc3c5f772a2d3e89ea05931e2726105fc53b9e601fc3231f35962c714fcbce5c95b427496edc7ae8b3d12e93791d7629795b62"
       },
       {
-        "exception": "Invalid signature length",
+        "exception": "Expected Buffer\\(Length: 65\\), got Buffer\\(Length: 68\\)",
         "hex": "1c987ceade6a304fc5823ab38f99fc3c5f772a2d3e89ea05931e2726105fc53b9e601fc3231f35962c714fcbce5c95b427496edc7ae8b3d12e93791d7629795b62000000"
       },
       {
-        "exception": "Invalid signature length",
+        "exception": "Expected Buffer\\(Length: 65\\), got Buffer\\(Length: 59\\)",
         "hex": "1c987ceade6a304fc5823ab38f99fc3c5f772a2d3e89ea05931e2726105fc53b9e601fc3231f35962c714fcbce5c95b427496edc7ae8b3d12e9379"
       }
     ],