From f53b821cc909176ad576d63f6cb3f2b5b38cfdb6 Mon Sep 17 00:00:00 2001
From: Daniel Cousens <daniel210x@gmail.com>
Date: Thu, 3 Apr 2014 19:45:05 +1100
Subject: [PATCH] Isolates Base58Check encoding from Base58 code/tests

---
 src/base58.js       | 94 +++++++++++++++------------------------------
 src/base58check.js  | 53 +++++++++++++++++++++++++
 src/index.js        |  1 +
 test/base58.js      | 66 ++++++++++++++++---------------
 test/base58check.js | 76 ++++++++++++++++++++++++++++++++++++
 5 files changed, 195 insertions(+), 95 deletions(-)
 create mode 100644 src/base58check.js
 create mode 100644 test/base58check.js

diff --git a/src/base58.js b/src/base58.js
index 0b38586..3715c3b 100644
--- a/src/base58.js
+++ b/src/base58.js
@@ -1,66 +1,65 @@
-// https://en.bitcoin.it/wiki/Base58Check_encoding
+// Base58 encoding/decoding
+// Originally written by Mike Hearn for BitcoinJ
+// Copyright (c) 2011 Google Inc
+// Ported to JavaScript by Stefan Thomas
 
 var BigInteger = require('./jsbn/jsbn')
-var Crypto = require('crypto-js')
-var convert = require('./convert')
-var SHA256 = Crypto.SHA256
 
+// FIXME: ? This is a Base58Check alphabet
 var alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
 var base = BigInteger.valueOf(58)
 
-var positions = {}
+var alphabetMap = {}
 for (var i=0; i<alphabet.length; ++i) {
-  positions[alphabet[i]] = i
+  var chr = alphabet[i]
+  alphabetMap[chr] = BigInteger.valueOf(i)
 }
 
-// Convert a byte array to a base58-encoded string.
-// Written by Mike Hearn for BitcoinJ.
-// Copyright (c) 2011 Google Inc.
-// Ported to JavaScript by Stefan Thomas.
-function encode(input) {
-  var bi = BigInteger.fromByteArrayUnsigned(input)
+// encode a byte array into a base58 encoded String
+// @return String
+function encode(buffer) {
+  var bi = BigInteger.fromByteArrayUnsigned(buffer)
   var chars = []
 
   while (bi.compareTo(base) >= 0) {
     var mod = bi.mod(base)
-    chars.push(alphabet[mod.intValue()])
     bi = bi.subtract(mod).divide(base)
+
+    chars.push(alphabet[mod.intValue()])
   }
 
   chars.push(alphabet[bi.intValue()])
 
   // Convert leading zeros too.
-  for (var i=0; i<input.length; i++) {
-    if (input[i] == 0x00) {
-      chars.push(alphabet[0])
-    } else break
+  for (var i=0; i<buffer.length; i++) {
+    if (buffer[i] !== 0x00) break
+
+    chars.push(alphabet[0])
   }
 
   return chars.reverse().join('')
 }
 
-// decode a base58 string into a byte array
-// input should be a base58 encoded string
+// decode a base58 encoded String into a byte array
 // @return Array
-function decode(input) {
-  var base = BigInteger.valueOf(58)
-
-  var length = input.length
+function decode(str) {
   var num = BigInteger.valueOf(0)
+
   var leading_zero = 0
   var seen_other = false
-  for (var i=0; i<length; ++i) {
-    var chr = input[i]
-    var p = positions[chr]
+
+  for (var i=0; i<str.length; ++i) {
+    var chr = str[i]
+    var bi = alphabetMap[chr]
 
     // if we encounter an invalid character, decoding fails
-    if (p === undefined) {
-      throw new Error('invalid base58 string: ' + input)
+    if (bi === undefined) {
+      throw new Error('invalid base58 string: ' + str)
     }
 
-    num = num.multiply(base).add(BigInteger.valueOf(p))
+    num = num.multiply(base).add(bi)
 
-    if (chr == '1' && !seen_other) {
+    if (chr === '1' && !seen_other) {
       ++leading_zero
     } else {
       seen_other = true
@@ -74,41 +73,10 @@ function decode(input) {
     bytes.unshift(0)
   }
 
-  return bytes
-}
-
-function checkEncode(input, vbyte) {
-  vbyte = vbyte || 0
-
-  var front = [vbyte].concat(input)
-  return encode(front.concat(getChecksum(front)))
-}
-
-function checkDecode(input) {
-  var bytes = decode(input),
-  front = bytes.slice(0, bytes.length-4),
-  back = bytes.slice(bytes.length-4)
-
-  var checksum = getChecksum(front)
-
-  if ("" + checksum != "" + back) {
-    throw new Error("Checksum failed")
-  }
-
-  var o = front.slice(1)
-  o.version = front[0]
-  return o
-}
-
-function getChecksum(bytes) {
-  var wordArray = convert.bytesToWordArray(bytes)
-  return convert.hexToBytes(SHA256(SHA256(wordArray)).toString()).slice(0, 4)
+  return new Buffer(bytes)
 }
 
 module.exports = {
   encode: encode,
-  decode: decode,
-  checkEncode: checkEncode,
-  checkDecode: checkDecode,
-  getChecksum: getChecksum
+  decode: decode
 }
diff --git a/src/base58check.js b/src/base58check.js
new file mode 100644
index 0000000..ca95048
--- /dev/null
+++ b/src/base58check.js
@@ -0,0 +1,53 @@
+// https://en.bitcoin.it/wiki/Base58Check_encoding
+var assert = require('assert')
+var base58 = require('./base58')
+var crypto = require('crypto')
+
+function sha256(buf) {
+  var hash = crypto.createHash('sha256')
+  hash.update(buf)
+
+  return hash.digest()
+}
+
+// Encode a buffer as a base58-check-encoded string
+function encode(buffer, version) {
+  version = version || 0
+
+  // FIXME: `new Buffer(buffer)` is unnecessary if input is a Buffer
+  var version = new Buffer([version])
+  var payload = new Buffer(buffer)
+
+  var message = Buffer.concat([version, payload])
+  var checksum = sha256(sha256(message)).slice(0, 4)
+
+  return base58.encode(Buffer.concat([
+    message,
+    checksum
+  ]))
+}
+
+// Decode a base58-check-encoded string to a buffer
+function decode(string) {
+  var buffer = base58.decode(string)
+
+  var message = buffer.slice(0, -4)
+  var checksum = buffer.slice(-4)
+  var newChecksum = sha256(sha256(message)).slice(0, 4)
+
+  assert.deepEqual(newChecksum, checksum)
+
+  var version = message.readUInt8(0)
+  var payload = message.slice(1)
+
+  return {
+    version: version,
+    payload: payload,
+    checksum: checksum
+  }
+}
+
+module.exports = {
+  encode: encode,
+  decode: decode
+}
diff --git a/src/index.js b/src/index.js
index c45c919..52fd4f4 100644
--- a/src/index.js
+++ b/src/index.js
@@ -21,5 +21,6 @@ module.exports = {
   ecdsa: require('./ecdsa'),
   HDWallet: require('./hdwallet.js'),
   base58: require('./base58'),
+  base58check: require('./base58check'),
   convert: require('./convert')
 }
diff --git a/test/base58.js b/test/base58.js
index 574db6d..fad2635 100644
--- a/test/base58.js
+++ b/test/base58.js
@@ -1,48 +1,50 @@
 var assert = require('assert')
 var base58 = require('../').base58
-var convert = require('../').convert
 
 describe('base58', function() {
-  describe('decode', function() {
-    it('validates known examples', function() {
-      var enc = '5HueCGU8rMjxEXxiPuD5BDku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ'
-      var hex = '800c28fca386c7a227600b2fe50b7cae11ec86d3bf1fbe471be89827e19d72aa1d507a5b8d'
-      assert.deepEqual(base58.decode(enc), convert.hexToBytes(hex))
-    })
-  })
+  var evec, dvec
 
-  describe('encode', function() {
-    it('handles known examples', function() {
-      var enc = '5HueCGU8rMjxEXxiPuD5BDku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ'
-      var hex = '800c28fca386c7a227600b2fe50b7cae11ec86d3bf1fbe471be89827e19d72aa1d507a5b8d'
-      assert.equal(base58.encode(convert.hexToBytes(hex)), enc)
+  beforeEach(function() {
+    // base58 encoded strings
+    evec = [
+      '5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAbuatmU', // 0x00 WIF
+      '5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf', // 0x01 WIF
+      '5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreQyNNN1W', // 0x7f WIF
+      '1EHNa6Q4Jz2uvNExL497mE43ikXhwF6kZm', // uncompressed 0x01 address
+      '1FB8cZijTpRQp3HX8AEkNuQJBqApqfTcX7' // uncompressed 0x7f address
+    ]
+
+    // decoded equivalent of above
+    dvec = [
+      '8000000000000000000000000000000000000000000000000000000000000000000565fba7',
+      '800000000000000000000000000000000000000000000000000000000000000001a85aa87e',
+      '80000000000000000000000000000000000000000000000000000000000000007f64046be9',
+      '0091b24bf9f5288532960ac687abb035127b1d28a50074ffe0',
+      '009b7c46977b68474e12066a370b169ec6b9b026444d210d6e'
+    ].map(function(h) {
+      return new Buffer(h, 'hex')
     })
   })
 
-  describe('checkEncode', function() {
-    it('handles known examples', function() {
-      var input = [
-        171, 210, 178, 125, 2, 16, 86, 184, 248, 88, 235,
-        163, 244, 160, 83, 156, 184, 186, 45, 167, 169, 164,
-        67, 125, 163, 89, 106, 243, 207, 193, 149, 206
-      ]
-      var vbyte = 239
+  describe('decode', function() {
+    it('decodes the test vectors', function() {
+      evec.forEach(function(x, i) {
+        var actual = base58.decode(x)
+        var expected = dvec[i]
 
-      assert.equal(base58.checkEncode(input, vbyte),
-                   '92tb9mjz6q9eKZjYvLsgk87kPrMoh7BGRumSzPeUGhmigtsfrbP')
+        assert.deepEqual(expected, actual)
+      })
     })
   })
 
-  describe('checkDecode', function() {
-    it('handles known examples', function() {
-      var input = '1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa'
-      var expected =  [
-        98, 233, 7, 177, 92, 191, 39, 213, 66, 83,
-        153, 235, 246, 240, 251, 80, 235, 184, 143, 24
-      ]
-      expected.version = 0
+  describe('encode', function() {
+    it('encodes the test vectors', function() {
+      dvec.forEach(function(x, i) {
+        var actual = base58.encode(x)
+        var expected = evec[i]
 
-      assert.deepEqual(base58.checkDecode(input), expected)
+        assert.deepEqual(expected, actual)
+      })
     })
   })
 })
diff --git a/test/base58check.js b/test/base58check.js
new file mode 100644
index 0000000..fdf7833
--- /dev/null
+++ b/test/base58check.js
@@ -0,0 +1,76 @@
+var assert = require('assert')
+var base58check = require('../').base58check
+
+describe('base58check', function() {
+  var evec, dvec
+
+  beforeEach(function() {
+    function fromHex(h) { return new Buffer(h, 'hex') }
+
+    // base58check encoded strings
+    evec = [
+      '5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAbuatmU', // 0x00 WIF
+      '5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf', // 0x01 WIF
+      '5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreQyNNN1W', // 0x7f WIF
+      '1EHNa6Q4Jz2uvNExL497mE43ikXhwF6kZm', // uncompressed 0x01 address
+      '1FB8cZijTpRQp3HX8AEkNuQJBqApqfTcX7' // uncompressed 0x7f address
+    ]
+
+    // decoded equivalent of above
+    dvec = [
+      {
+        version: 0x80,
+        payload: '0000000000000000000000000000000000000000000000000000000000000000',
+        checksum: '0565fba7'
+      },
+      {
+        version: 0x80,
+        payload: '0000000000000000000000000000000000000000000000000000000000000001',
+        checksum: 'a85aa87e',
+      },
+      {
+        version: 0x80,
+        payload: '000000000000000000000000000000000000000000000000000000000000007f',
+        checksum: '64046be9',
+      },
+      {
+        version: 0x00,
+        payload: '91b24bf9f5288532960ac687abb035127b1d28a5',
+        checksum: '0074ffe0',
+      },
+      {
+        version: 0x00,
+        payload: '9b7c46977b68474e12066a370b169ec6b9b02644',
+        checksum: '4d210d6e'
+      }
+    ].map(function(x) {
+      return {
+        version: x.version,
+        payload: fromHex(x.payload),
+        checksum: fromHex(x.checksum)
+      }
+    })
+  })
+
+  describe('decode', function() {
+    it('decodes the test vectors', function() {
+      evec.forEach(function(x, i) {
+        var actual = base58check.decode(x)
+        var expected = dvec[i]
+
+        assert.deepEqual(expected, actual)
+      })
+    })
+  })
+
+  describe('encode', function() {
+    it('encodes the test vectors', function() {
+      dvec.forEach(function(x, i) {
+        var actual = base58check.encode(x.payload, x.version)
+        var expected = evec[i]
+
+        assert.deepEqual(expected, actual)
+      })
+    })
+  })
+})