ecdsa: moved all signature encoding to ECSignature

src/ecsignature.js

@@ -0,0 +1,102 @@
+var assert = require('assert')
+
+var BigInteger = require('bigi')
+
+function ECSignature(r, s) {
+  assert(r instanceof BigInteger, 'Expected BigInteger, got ' + r)
+  assert(s instanceof BigInteger, 'Expected BigInteger, got ' + s)
+  this.r = r
+  this.s = s
+}
+
+// Import operations
+ECSignature.fromCompact = function(buffer) {
+  assert.equal(buffer.length, 65, 'Invalid signature length')
+  var i = buffer.readUInt8(0) - 27
+
+  // At most 3 bits
+  assert.equal(i, i & 7, 'Invalid signature parameter')
+  var compressed = !!(i & 4)
+
+  // Recovery param only
+  i = i & 3
+
+  var r = BigInteger.fromBuffer(buffer.slice(1, 33))
+  var s = BigInteger.fromBuffer(buffer.slice(33))
+
+  return {
+    compressed: compressed,
+    i: i,
+    signature: new ECSignature(r, s)
+  }
+}
+
+ECSignature.fromDER = function(buffer) {
+  assert.equal(buffer.readUInt8(0), 0x30, 'Not a DER sequence')
+  assert.equal(buffer.readUInt8(1), buffer.length - 2, 'Invalid sequence length')
+
+  assert.equal(buffer.readUInt8(2), 0x02, 'Expected a DER integer')
+  var rLen = buffer.readUInt8(3)
+  var rB = buffer.slice(4, 4 + rLen)
+
+  var offset = 4 + rLen
+  assert.equal(buffer.readUInt8(offset), 0x02, 'Expected a DER integer (2)')
+  var sLen = buffer.readUInt8(1 + offset)
+  var sB = buffer.slice(2 + offset)
+  offset += 2 + sLen
+
+  assert.equal(offset, buffer.length, 'Invalid DER encoding')
+  var r = BigInteger.fromDERInteger(rB)
+  var s = BigInteger.fromDERInteger(sB)
+
+  return new ECSignature(r, s)
+}
+
+ECSignature.fromScriptSignature = function(buffer) {
+  return {
+    signature: ECSignature.fromDER(buffer.slice(0, -1)),
+    hashType: buffer.readUInt8(buffer.length - 1)
+  }
+}
+
+// Export operations
+ECSignature.prototype.toCompact = function(i, compressed) {
+  if (compressed) i += 4
+  i += 27
+
+  var buffer = new Buffer(65)
+  buffer.writeUInt8(i, 0)
+
+  this.r.toBuffer(32).copy(buffer, 1)
+  this.s.toBuffer(32).copy(buffer, 33)
+
+  return buffer
+}
+
+ECSignature.prototype.toDER = function() {
+  var rBa = this.r.toDERInteger()
+  var sBa = this.s.toDERInteger()
+
+  var sequence = []
+  sequence.push(0x02) // INTEGER
+  sequence.push(rBa.length)
+  sequence = sequence.concat(rBa)
+
+  sequence.push(0x02) // INTEGER
+  sequence.push(sBa.length)
+  sequence = sequence.concat(sBa)
+
+  sequence.unshift(sequence.length)
+  sequence.unshift(0x30) // SEQUENCE
+
+  return new Buffer(sequence)
+}
+
+ECSignature.prototype.toScriptSignature = function(hashType) {
+  var hashTypeBuffer = new Buffer(1)
+  hashTypeBuffer.writeUInt8(hashType, 0)
+
+  return Buffer.concat([this.toDER(), hashTypeBuffer])
+}
+
+module.exports = ECSignature