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index: clarify BIP39 compliance

This commit is contained in:
Daniel Cousens 2014-06-23 15:49:54 +10:00
parent 1f6915bd01
commit b41eefd395
1 changed files with 30 additions and 17 deletions
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47
index.js
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@ -17,17 +17,19 @@ BIP39.prototype.mnemonicToSeed = function(mnemonic, password) {
BIP39.prototype.entropyToMnemonic = function(entropy) {
var entropyBuffer = new Buffer(entropy, 'hex')
var hash = crypto.createHash('sha256').update(entropyBuffer).digest()
var entropyBits = bytesToBinary([].slice.call(entropyBuffer))
var checksum = checksumBits(entropyBuffer)
var combined = Buffer.concat([entropyBuffer, hash])
var bitLength = entropyBuffer.length * 8 + entropyBuffer.length / 4
var bits = bytesToBinary([].slice.call(combined)).substr(0, bitLength)
var bits = entropyBits + checksum
var chunks = bits.match(/(.{1,11})/g)
var chunks = (bits).match(/(.{1,11})/g)
return chunks.map(function(binary) {
var words = chunks.map(function(binary) {
var index = parseInt(binary, 2)
return this.wordlist[index]
}, this).join(' ')
}, this)
return words.join(' ')
}
BIP39.prototype.generateMnemonic = function(strength) {
@ -48,24 +50,35 @@ BIP39.prototype.validate = function(mnemonic) {
if (!belongToList) return false
// convert word indices to 11 bit binary strings
var bits = words.map(function(word) {
var id = wordlist.indexOf(word)
return lpad(id.toString(2), '0', 11)
var index = wordlist.indexOf(word)
return lpad(index.toString(2), '0', 11)
}).join('')
var length = bits.length
var dividerIndex = Math.floor(length / 33) * 32
// split the binary string into ENT/CS
var dividerIndex = Math.floor(bits.length / 33) * 32
var entropy = bits.substring(0, dividerIndex)
var checksum = bits.substring(dividerIndex)
var data = bits.substring(0, dividerIndex)
var bytes = data.match(/(.{1,8})/g).map(function(bin) {
// calculate the checksum and compare
var entropyBytes = entropy.match(/(.{1,8})/g).map(function(bin) {
return parseInt(bin, 2)
})
var hash = crypto.createHash('sha256').update(new Buffer(bytes)).digest()
var checksumBits = bytesToBinary([].slice.call(hash))
var checksum2 = checksumBits.substr(0, length - dividerIndex)
var entropyBuffer = new Buffer(entropyBytes)
var newChecksum = checksumBits(entropyBuffer)
return checksum === checksum2
return newChecksum === checksum
}
function checksumBits(entropyBuffer) {
var hash = crypto.createHash('sha256').update(entropyBuffer).digest()
// Calculated constants from BIP39
var ENT = entropyBuffer.length * 8
var CS = ENT / 32
return bytesToBinary([].slice.call(hash)).substr(0, CS)
}
function salt(password) {