Merge pull request #49 from bitcoinjs/ent

Limit ENT to 128-256, multiple of 4 (cont.)
bitcoinjs · May 23, 2017 · 9b12ca4 · 9b12ca4
2 parents f6bcccc + 59cfe5d
commit 9b12ca4
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diff --git a/README.md b/README.md
@@ -42,8 +42,8 @@ var bip39 = require('bip39')
 
 // defaults to BIP39 English word list
 // uses HEX strings for entropy
-var mnemonic = bip39.entropyToMnemonic('133755ff')
-// => basket rival lemon
+var mnemonic = bip39.entropyToMnemonic('00000000000000000000000000000000')
+// => zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo wrong
 
 // reversible
 bip39.mnemonicToEntropy(mnemonic)

diff --git a/index.js b/index.js
@@ -12,6 +12,33 @@ var JAPANESE_WORDLIST = require('./wordlists/japanese.json')
 var SPANISH_WORDLIST = require('./wordlists/spanish.json')
 var DEFAULT_WORDLIST = ENGLISH_WORDLIST
 
+var INVALID_MNEMONIC = 'Invalid mnemonic'
+var INVALID_ENTROPY = 'Invalid entropy'
+var INVALID_CHECKSUM = 'Invalid mnemonic checksum'
+
+function lpad (str, padString, length) {
+  while (str.length < length) str = padString + str
+  return str
+}
+
+function binaryToByte (bin) {
+  return parseInt(bin, 2)
+}
+
+function bytesToBinary (bytes) {
+  return bytes.map(function (x) {
+    return lpad(x.toString(2), '0', 8)
+  }).join('')
+}
+
+function deriveChecksumBits (entropyBuffer) {
+  var ENT = entropyBuffer.length * 8
+  var CS = ENT / 32
+  var hash = createHash('sha256').update(entropyBuffer).digest()
+
+  return bytesToBinary([].slice.call(hash)).slice(0, CS)
+}
+
 function salt (password) {
   return 'mnemonic' + (password || '')
 }
@@ -31,57 +58,52 @@ function mnemonicToEntropy (mnemonic, wordlist) {
   wordlist = wordlist || DEFAULT_WORDLIST
 
   var words = unorm.nfkd(mnemonic).split(' ')
-  if (words.length % 3 !== 0) throw new Error('Invalid mnemonic')
-  if (words.some(function (word) {
-    return wordlist.indexOf(word) === -1
-  })) throw new Error('Invalid mnemonic')
+  if (words.length % 3 !== 0) throw new Error(INVALID_MNEMONIC)
 
   // convert word indices to 11 bit binary strings
   var bits = words.map(function (word) {
     var index = wordlist.indexOf(word)
+    if (index === -1) throw new Error(INVALID_MNEMONIC)
+
     return lpad(index.toString(2), '0', 11)
   }).join('')
 
-  // max entropy is 1024; (1024×8)+((1024×8)÷32) = 8448
-  if (bits.length > 8448) {
-    throw new Error('Invalid mnemonic')
-  }
-
   // split the binary string into ENT/CS
   var dividerIndex = Math.floor(bits.length / 33) * 32
-  var entropy = bits.slice(0, dividerIndex)
-  var checksum = bits.slice(dividerIndex)
+  var entropyBits = bits.slice(0, dividerIndex)
+  var checksumBits = bits.slice(dividerIndex)
 
   // calculate the checksum and compare
-  var entropyBytes = entropy.match(/(.{1,8})/g).map(function (bin) {
-    return parseInt(bin, 2)
-  })
-  var entropyBuffer = new Buffer(entropyBytes)
-  var newChecksum = checksumBits(entropyBuffer)
+  var entropyBytes = entropyBits.match(/(.{1,8})/g).map(binaryToByte)
+  if (entropyBytes.length < 16) throw new Error(INVALID_ENTROPY)
+  if (entropyBytes.length > 32) throw new Error(INVALID_ENTROPY)
+  if (entropyBytes.length % 4 !== 0) throw new Error(INVALID_ENTROPY)
 
-  if (newChecksum !== checksum) throw new Error('Invalid mnemonic checksum')
+  var entropy = new Buffer(entropyBytes)
+  var newChecksum = deriveChecksumBits(entropy)
+  if (newChecksum !== checksumBits) throw new Error(INVALID_CHECKSUM)
 
-  return entropyBuffer.toString('hex')
+  return entropy.toString('hex')
 }
 
-function entropyToMnemonic (entropy, wordlist) {
+function entropyToMnemonic (entropyHex, wordlist) {
   wordlist = wordlist || DEFAULT_WORDLIST
 
-  var entropyBuffer = new Buffer(entropy, 'hex')
+  // 128 <= ENT <= 256
+  if (entropyHex.length < 32) throw new TypeError(INVALID_ENTROPY)
+  if (entropyHex.length > 64) throw new TypeError(INVALID_ENTROPY)
 
-  if (entropyBuffer.length === 0 || entropyBuffer.length > 1024 || entropyBuffer.length % 4 !== 0) {
-    throw new Error('Invalid entropy')
-  }
+  // multiple of 4
+  if (entropyHex.length % 8 !== 0) throw new TypeError(INVALID_ENTROPY)
 
-  var entropyBits = bytesToBinary([].slice.call(entropyBuffer))
-  var checksum = checksumBits(entropyBuffer)
+  var entropy = new Buffer(entropyHex, 'hex')
+  var entropyBits = bytesToBinary([].slice.call(entropy))
+  var checksumBits = deriveChecksumBits(entropy)
 
-  var bits = entropyBits + checksum
+  var bits = entropyBits + checksumBits
   var chunks = bits.match(/(.{1,11})/g)
-
   var words = chunks.map(function (binary) {
-    var index = parseInt(binary, 2)
-
+    var index = binaryToByte(binary)
     return wordlist[index]
   })
 
@@ -90,6 +112,7 @@ function entropyToMnemonic (entropy, wordlist) {
 
 function generateMnemonic (strength, rng, wordlist) {
   strength = strength || 128
+  if (strength % 32 !== 0) throw new TypeError(INVALID_ENTROPY)
   rng = rng || randomBytes
 
   var hex = rng(strength / 8).toString('hex')
@@ -106,29 +129,6 @@ function validateMnemonic (mnemonic, wordlist) {
   return true
 }
 
-function checksumBits (entropyBuffer) {
-  var hash = createHash('sha256').update(entropyBuffer).digest()
-
-  // Calculated constants from BIP39
-  var ENT = entropyBuffer.length * 8
-  var CS = ENT / 32
-
-  return bytesToBinary([].slice.call(hash)).slice(0, CS)
-}
-
-// =========== helper methods from bitcoinjs-lib ========
-
-function bytesToBinary (bytes) {
-  return bytes.map(function (x) {
-    return lpad(x.toString(2), '0', 8)
-  }).join('')
-}
-
-function lpad (str, padString, length) {
-  while (str.length < length) str = padString + str
-  return str
-}
-
 module.exports = {
   mnemonicToSeed: mnemonicToSeed,
   mnemonicToSeedHex: mnemonicToSeedHex,

diff --git a/package.json b/package.json
@@ -33,7 +33,7 @@
     "node-fetch": "^1.6.3",
     "nyc": "^8.3.0",
     "proxyquire": "^1.7.10",
-    "standard": "*",
+    "standard": "^9.0.0",
     "tape": "^4.6.2"
   }
 }
diff --git a/test/index.js b/test/index.js
@@ -1,5 +1,4 @@
 var bip39 = require('../')
-var proxyquire = require('proxyquire')
 var download = require('../util/wordlists').download
 var WORDLISTS = {
   english: require('../wordlists/english.json'),
@@ -15,7 +14,7 @@ function testVector (description, wordlist, password, v, i) {
   var vmnemonic = v[1]
   var vseedHex = v[2]
 
-  test('for ' + description + ' test vector ' + i, function (t) {
+  test('for ' + description + '(' + i + '), ' + ventropy, function (t) {
     t.plan(5)
 
     t.equal(bip39.mnemonicToEntropy(vmnemonic, wordlist), ventropy, 'mnemonicToEntropy returns ' + ventropy.slice(0, 40) + '...')
@@ -37,15 +36,15 @@ test('invalid entropy', function (t) {
 
   t.throws(function () {
     bip39.entropyToMnemonic(new Buffer('', 'hex'))
-  }, /^Invalid entropy$/, 'throws for empty entropy')
+  }, /^TypeError: Invalid entropy$/, 'throws for empty entropy')
 
   t.throws(function () {
     bip39.entropyToMnemonic(new Buffer('000000', 'hex'))
-  }, /^Invalid entropy$/, 'throws for entropy that\'s not a multitude of 4 bytes')
+  }, /^TypeError: Invalid entropy$/, 'throws for entropy that\'s not a multitude of 4 bytes')
 
   t.throws(function () {
     bip39.entropyToMnemonic(new Buffer(new Array(1028 + 1).join('00'), 'hex'))
-  }, /^Invalid entropy$/, 'throws for entropy that is larger than 1024')
+  }, /^TypeError: Invalid entropy$/, 'throws for entropy that is larger than 1024')
 })
 
 test('UTF8 passwords', function (t) {
@@ -63,57 +62,18 @@ test('UTF8 passwords', function (t) {
   })
 })
 
-test('README example 1', function (t) {
-  // defaults to BIP39 English word list
-  var entropy = '133755ff'
-  var mnemonic = bip39.entropyToMnemonic(entropy)
-
-  t.plan(2)
-  t.equal(mnemonic, 'basket rival lemon')
-
-  // reversible
-  t.equal(bip39.mnemonicToEntropy(mnemonic), entropy)
-})
-
-test('README example 2', function (t) {
-  var stub = {
-    randombytes: function (size) {
-      return new Buffer('qwertyuiopasdfghjklzxcvbnm[];,./'.slice(0, size))
-    }
-  }
-  var proxiedbip39 = proxyquire('../', stub)
-
-  // mnemonic strength defaults to 128 bits
-  var mnemonic = proxiedbip39.generateMnemonic()
-
-  t.plan(2)
-  t.equal(mnemonic, 'imitate robot frame trophy nuclear regret saddle around inflict case oil spice')
-  t.equal(bip39.validateMnemonic(mnemonic), true)
-})
-
-test('README example 3', function (t) {
-  var mnemonic = 'basket actual'
-  var seed = bip39.mnemonicToSeed(mnemonic)
-  var seedHex = bip39.mnemonicToSeedHex(mnemonic)
-
-  t.plan(3)
-  t.equal(seed.toString('hex'), seedHex)
-  t.equal(seedHex, '5cf2d4a8b0355e90295bdfc565a022a409af063d5365bb57bf74d9528f494bfa4400f53d8349b80fdae44082d7f9541e1dba2b003bcfec9d0d53781ca676651f')
-  t.equal(bip39.validateMnemonic(mnemonic), false)
-})
-
 test('generateMnemonic can vary entropy length', function (t) {
-  var words = bip39.generateMnemonic(96).split(' ')
+  var words = bip39.generateMnemonic(160).split(' ')
 
   t.plan(1)
-  t.equal(words.length, 9, 'can vary generated entropy bit length')
+  t.equal(words.length, 15, 'can vary generated entropy bit length')
 })
 
-test('generateMnemonic only requests the exact amount of data from an RNG', function (t) {
+test('generateMnemonic requests the exact amount of data from an RNG', function (t) {
   t.plan(1)
 
-  bip39.generateMnemonic(96, function (size) {
-    t.equal(size, 96 / 8)
+  bip39.generateMnemonic(160, function (size) {
+    t.equal(size, 160 / 8)
     return new Buffer(size)
   })
 })

diff --git a/test/readme.js b/test/readme.js
@@ -0,0 +1,42 @@
+var bip39 = require('../')
+var proxyquire = require('proxyquire')
+var test = require('tape')
+
+test('README example 1', function (t) {
+  // defaults to BIP39 English word list
+  var entropy = 'ffffffffffffffffffffffffffffffff'
+  var mnemonic = bip39.entropyToMnemonic(entropy)
+
+  t.plan(2)
+  t.equal(mnemonic, 'zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo wrong')
+
+  // reversible
+  t.equal(bip39.mnemonicToEntropy(mnemonic), entropy)
+})
+
+test('README example 2', function (t) {
+  var stub = {
+    randombytes: function (size) {
+      return new Buffer('qwertyuiopasdfghjklzxcvbnm[];,./'.slice(0, size))
+    }
+  }
+  var proxiedbip39 = proxyquire('../', stub)
+
+  // mnemonic strength defaults to 128 bits
+  var mnemonic = proxiedbip39.generateMnemonic()
+
+  t.plan(2)
+  t.equal(mnemonic, 'imitate robot frame trophy nuclear regret saddle around inflict case oil spice')
+  t.equal(bip39.validateMnemonic(mnemonic), true)
+})
+
+test('README example 3', function (t) {
+  var mnemonic = 'basket actual'
+  var seed = bip39.mnemonicToSeed(mnemonic)
+  var seedHex = bip39.mnemonicToSeedHex(mnemonic)
+
+  t.plan(3)
+  t.equal(seed.toString('hex'), seedHex)
+  t.equal(seedHex, '5cf2d4a8b0355e90295bdfc565a022a409af063d5365bb57bf74d9528f494bfa4400f53d8349b80fdae44082d7f9541e1dba2b003bcfec9d0d53781ca676651f')
+  t.equal(bip39.validateMnemonic(mnemonic), false)
+})