ECKey: remove *Buffer/*Hex functions

An ECKey is a composition of a private key (D), a public key (Q) and its
compression flag.

These functions gave the impression of serialization of this
composition, when really they only serialized `D`.
They have therefore been removed in favour of always using a sane
serialization format (WIF) that matches the needed behaviour.

If a user needs the previous functionality, simply use `privKey.D.*`
instead of `privKey.*`, as BigInteger supports `*Buffer/*Hex` functions
as expected.

src/eckey.js

@@ -21,29 +21,22 @@ function ECKey(D, compressed) {
 }
 
 // Static constructors
-ECKey.fromBuffer = function(buffer, compressed) {
-  assert(Buffer.isBuffer(buffer), 'First argument must be a Buffer')
-  assert.strictEqual(buffer.length, 32, 'Invalid buffer length')
-
-  var D = BigInteger.fromBuffer(buffer)
-  return new ECKey(D, compressed)
-}
-
-ECKey.fromHex = function(hex, compressed) {
-  return ECKey.fromBuffer(new Buffer(hex, 'hex'), compressed)
-}
-
 ECKey.fromWIF = function(string) {
   var decode = base58check.decode(string)
-
   var payload = decode.payload
+  var compressed = false
+
   if (payload.length === 33) {
     assert.strictEqual(payload[32], 0x01, 'Invalid WIF string')
 
-    return ECKey.fromBuffer(payload.slice(0, 32), true)
+    payload = payload.slice(0, -1)
+    compressed = true
   }
 
-  return ECKey.fromBuffer(payload, false)
+  assert.equal(payload.length, 32, 'Invalid WIF payload length')
+
+  var D = BigInteger.fromBuffer(payload.slice(0, 32))
+  return new ECKey(D, compressed)
 }
 
 ECKey.makeRandom = function(compressed, rng) {
@@ -56,24 +49,11 @@ ECKey.makeRandom = function(compressed, rng) {
   return new ECKey(D, compressed)
 }
 
-// Operations
-ECKey.prototype.sign = function(hash) {
-  return ecdsa.sign(hash, this.D)
-}
-
 // Export functions
-ECKey.prototype.toBuffer = function() {
-  return this.D.toBuffer(32)
-}
-
-ECKey.prototype.toHex = function() {
-  return this.toBuffer().toString('hex')
-}
-
 ECKey.prototype.toWIF = function(version) {
   version = version || networks.bitcoin.wif
 
-  var buffer = this.toBuffer()
+  var buffer = this.D.toBuffer(32)
   if (this.pub.compressed) {
     buffer = Buffer.concat([buffer, new Buffer([0x01])])
   }
@@ -81,4 +61,9 @@ ECKey.prototype.toWIF = function(version) {
   return base58check.encode(buffer, version)
 }
 
+// Operations
+ECKey.prototype.sign = function(hash) {
+  return ecdsa.sign(hash, this.D)
+}
+
 module.exports = ECKey