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RIPEMD-160實作原理

步驟ㄧ:

官方公式定義:

根據 j 的值不同，函式計算方式也不同

符號意思分別為

步驟二:

然後加上hash時會用到的常數constant

1.

將其分為hl與hr
const hl = [0x00000000, 0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xa953fd4e];
const hr = [0x50a28be6, 0x5c4dd124, 0x6d703ef3, 0x7a6d76e9, 0x00000000];

對照上圖最右側公式 "5a827999" = (2 ** 30 * (Math.sqrt(2))).toString(16).substring(0,8)

2.selection of message word

寫為如下：

const zl = [
  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
  7, 4, 13, 1, 10, 6, 15, 3, 12, 0, 9, 5, 2, 14, 11, 8,
  3, 10, 14, 4, 9, 15, 8, 1, 2, 7, 0, 6, 13, 11, 5, 12,
  1, 9, 11, 10, 0, 8, 12, 4, 13, 3, 7, 15, 14, 5, 6, 2,
  4, 0, 5, 9, 7, 12, 2, 10, 14, 1, 3, 8, 11, 6, 15, 13
]

const zr = [
  5, 14, 7, 0, 9, 2, 11, 4, 13, 6, 15, 8, 1, 10, 3, 12,
  6, 11, 3, 7, 0, 13, 5, 10, 14, 15, 8, 12, 4, 9, 1, 2,
  15, 5, 1, 3, 7, 14, 6, 9, 11, 8, 12, 2, 10, 0, 4, 13,
  8, 6, 4, 1, 3, 11, 15, 0, 5, 12, 2, 13, 9, 7, 10, 14,
  12, 15, 10, 4, 1, 5, 8, 7, 6, 2, 13, 14, 0, 3, 9, 11
]

3.Amount for rotate left (rol)

const sl = [
  11, 14, 15, 12, 5, 8, 7, 9, 11, 13, 14, 15, 6, 7, 9, 8,
  7, 6, 8, 13, 11, 9, 7, 15, 7, 12, 15, 9, 11, 7, 13, 12,
  11, 13, 6, 7, 14, 9, 13, 15, 14, 8, 13, 6, 5, 12, 7, 5,
  11, 12, 14, 15, 14, 15, 9, 8, 9, 14, 5, 6, 8, 6, 5, 12,
  9, 15, 5, 11, 6, 8, 13, 12, 5, 12, 13, 14, 11, 8, 5, 6
]

var sr = [
  8, 9, 9, 11, 13, 15, 15, 5, 7, 7, 8, 11, 14, 14, 12, 6,
  9, 13, 15, 7, 12, 8, 9, 11, 7, 7, 12, 7, 6, 15, 13, 11,
  9, 7, 15, 11, 8, 6, 6, 14, 12, 13, 5, 14, 13, 13, 7, 5,
  15, 5, 8, 11, 14, 14, 6, 14, 6, 9, 12, 9, 12, 5, 15, 8,
  8, 5, 12, 9, 12, 5, 14, 6, 8, 13, 6, 5, 15, 13, 11, 11
]
最後寫上initial value

看完上面定義的這些數字可能會有點模糊，不知道他們是用來做什麼的

所以我們直接來看整個hash過程的pseudo-code

寫成JS

function rotl (x, n) {
  return (x << n) | (x >>> (32 - n))
}

function fn1 (a, b, c, d, e, m, k, s) {
  return (rotl((a + (b ^ c ^ d) + m + k) | 0, s) + e) | 0
}

function fn2 (a, b, c, d, e, m, k, s) {
  return (rotl((a + ((b & c) | ((~b) & d)) + m + k) | 0, s) + e) | 0
}

function fn3 (a, b, c, d, e, m, k, s) {
  return (rotl((a + ((b | (~c)) ^ d) + m + k) | 0, s) + e) | 0
}

function fn4 (a, b, c, d, e, m, k, s) {
  return (rotl((a + ((b & d) | (c & (~d))) + m + k) | 0, s) + e) | 0
}

function fn5 (a, b, c, d, e, m, k, s) {
  return (rotl((a + (b ^ (c | (~d))) + m + k) | 0, s) + e) | 0
}

for (var i = 0; i < 80; i += 1) {
    var tl
    var tr
    if (i < 16) {
      tl = fn1(al, bl, cl, dl, el, words[zl[i]], hl[0], sl[i])
      tr = fn5(ar, br, cr, dr, er, words[zr[i]], hr[0], sr[i])
    } else if (i < 32) {
      tl = fn2(al, bl, cl, dl, el, words[zl[i]], hl[1], sl[i])
      tr = fn4(ar, br, cr, dr, er, words[zr[i]], hr[1], sr[i])
    } else if (i < 48) {
      tl = fn3(al, bl, cl, dl, el, words[zl[i]], hl[2], sl[i])
      tr = fn3(ar, br, cr, dr, er, words[zr[i]], hr[2], sr[i])
    } else if (i < 64) {
      tl = fn4(al, bl, cl, dl, el, words[zl[i]], hl[3], sl[i])
      tr = fn2(ar, br, cr, dr, er, words[zr[i]], hr[3], sr[i])
    } else { // if (i<80) {
      tl = fn5(al, bl, cl, dl, el, words[zl[i]], hl[4], sl[i])
      tr = fn1(ar, br, cr, dr, er, words[zr[i]], hr[4], sr[i])
    }

    al = el
    el = dl
    dl = rotl(cl, 10)
    cl = bl
    bl = tl

    ar = er
    er = dr
    dr = rotl(cr, 10)
    cr = br
    br = tr
}

最後，把一開始的constant的每個數值加上新hash過的數字更新然後串接起來

  let t = (this._b + cl + dr) | 0
  this._b = (this._c + dl + er) | 0
  this._c = (this._d + el + ar) | 0
  this._d = (this._e + al + br) | 0
  this._e = (this._a + bl + cr) | 0
  this._a = t

  let buffer = new Buffer(20)
  buffer.writeInt32LE(this._a, 0)
  buffer.writeInt32LE(this._b, 4)
  buffer.writeInt32LE(this._c, 8)
  buffer.writeInt32LE(this._d, 12)
  buffer.writeInt32LE(this._e, 16)
  return buffer

--------------------------------------------------------------------------------------------------------------------

完整程式碼

const util = require('util');

function HashBase(blockSize) {
  this._block = Buffer.allocUnsafe(blockSize)
  this._blockSize = blockSize
  this._blockOffset = 0
  this._length = [0, 0, 0, 0]

  this._finalized = false
}


HashBase.prototype.update = function (data, encoding) {
  if (this._finalized) throw new Error('Digest already called')
  if (!Buffer.isBuffer(data)) data = Buffer.from(data, encoding)

  // consume data
  var block = this._block
  var offset = 0
  while (this._blockOffset + data.length - offset >= this._blockSize) {
    for (var i = this._blockOffset; i < this._blockSize;) block[i++] = data[offset++]
    this._update()
    this._blockOffset = 0
  }
  while (offset < data.length) block[this._blockOffset++] = data[offset++]

  // update length
  for (var j = 0, carry = data.length * 8; carry > 0; ++j) {
    this._length[j] += carry
    carry = (this._length[j] / 0x0100000000) | 0
    if (carry > 0) this._length[j] -= 0x0100000000 * carry
  }

  return this
}

HashBase.prototype._update = function () {
  throw new Error('_update is not implemented')
}

HashBase.prototype.digest = function (encoding) {
  if (this._finalized) throw new Error('Digest already called')
  this._finalized = true

  var digest = this._digest()
  if (encoding !== undefined) digest = digest.toString(encoding)

  // reset state
  this._block.fill(0)
  this._blockOffset = 0
  for (var i = 0; i < 4; ++i) this._length[i] = 0

  return digest
}


var zl = [
  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
  7, 4, 13, 1, 10, 6, 15, 3, 12, 0, 9, 5, 2, 14, 11, 8,
  3, 10, 14, 4, 9, 15, 8, 1, 2, 7, 0, 6, 13, 11, 5, 12,
  1, 9, 11, 10, 0, 8, 12, 4, 13, 3, 7, 15, 14, 5, 6, 2,
  4, 0, 5, 9, 7, 12, 2, 10, 14, 1, 3, 8, 11, 6, 15, 13
]

var zr = [
  5, 14, 7, 0, 9, 2, 11, 4, 13, 6, 15, 8, 1, 10, 3, 12,
  6, 11, 3, 7, 0, 13, 5, 10, 14, 15, 8, 12, 4, 9, 1, 2,
  15, 5, 1, 3, 7, 14, 6, 9, 11, 8, 12, 2, 10, 0, 4, 13,
  8, 6, 4, 1, 3, 11, 15, 0, 5, 12, 2, 13, 9, 7, 10, 14,
  12, 15, 10, 4, 1, 5, 8, 7, 6, 2, 13, 14, 0, 3, 9, 11
]

var sl = [
  11, 14, 15, 12, 5, 8, 7, 9, 11, 13, 14, 15, 6, 7, 9, 8,
  7, 6, 8, 13, 11, 9, 7, 15, 7, 12, 15, 9, 11, 7, 13, 12,
  11, 13, 6, 7, 14, 9, 13, 15, 14, 8, 13, 6, 5, 12, 7, 5,
  11, 12, 14, 15, 14, 15, 9, 8, 9, 14, 5, 6, 8, 6, 5, 12,
  9, 15, 5, 11, 6, 8, 13, 12, 5, 12, 13, 14, 11, 8, 5, 6
]

var sr = [
  8, 9, 9, 11, 13, 15, 15, 5, 7, 7, 8, 11, 14, 14, 12, 6,
  9, 13, 15, 7, 12, 8, 9, 11, 7, 7, 12, 7, 6, 15, 13, 11,
  9, 7, 15, 11, 8, 6, 6, 14, 12, 13, 5, 14, 13, 13, 7, 5,
  15, 5, 8, 11, 14, 14, 6, 14, 6, 9, 12, 9, 12, 5, 15, 8,
  8, 5, 12, 9, 12, 5, 14, 6, 8, 13, 6, 5, 15, 13, 11, 11
]

var hl = [0x00000000, 0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xa953fd4e]
var hr = [0x50a28be6, 0x5c4dd124, 0x6d703ef3, 0x7a6d76e9, 0x00000000]

function RIPEMD160() {
  HashBase.call(this, 64)

  // state
  this._a = 0x67452301
  this._b = 0xefcdab89
  this._c = 0x98badcfe
  this._d = 0x10325476
  this._e = 0xc3d2e1f0
}

util.inherits(RIPEMD160, HashBase)

RIPEMD160.prototype._update = function () {
  const words = new Array(16)
  for (var j = 0; j < 16; ++j) words[j] = this._block.readInt32LE(j * 4)

  var al = this._a | 0
  var bl = this._b | 0
  var cl = this._c | 0
  var dl = this._d | 0
  var el = this._e | 0

  var ar = this._a | 0
  var br = this._b | 0
  var cr = this._c | 0
  var dr = this._d | 0
  var er = this._e | 0

  // computation
  for (var i = 0; i < 80; i += 1) {
    var tl
    var tr
    if (i < 16) {
      tl = fn1(al, bl, cl, dl, el, words[zl[i]], hl[0], sl[i])
      tr = fn5(ar, br, cr, dr, er, words[zr[i]], hr[0], sr[i])
    } else if (i < 32) {
      tl = fn2(al, bl, cl, dl, el, words[zl[i]], hl[1], sl[i])
      tr = fn4(ar, br, cr, dr, er, words[zr[i]], hr[1], sr[i])
    } else if (i < 48) {
      tl = fn3(al, bl, cl, dl, el, words[zl[i]], hl[2], sl[i])
      tr = fn3(ar, br, cr, dr, er, words[zr[i]], hr[2], sr[i])
    } else if (i < 64) {
      tl = fn4(al, bl, cl, dl, el, words[zl[i]], hl[3], sl[i])
      tr = fn2(ar, br, cr, dr, er, words[zr[i]], hr[3], sr[i])
    } else { // i < 80
      tl = fn5(al, bl, cl, dl, el, words[zl[i]], hl[4], sl[i])
      tr = fn1(ar, br, cr, dr, er, words[zr[i]], hr[4], sr[i])
    }

    al = el
    el = dl
    dl = rotl(cl, 10)
    cl = bl
    bl = tl

    ar = er
    er = dr
    dr = rotl(cr, 10)
    cr = br
    br = tr
  }

  // update state
  var t = (this._b + cl + dr) | 0
  this._b = (this._c + dl + er) | 0
  this._c = (this._d + el + ar) | 0
  this._d = (this._e + al + br) | 0
  this._e = (this._a + bl + cr) | 0
  this._a = t
}

RIPEMD160.prototype._digest = function () {
  // create padding and handle blocks
  this._block[this._blockOffset++] = 0x80
  if (this._blockOffset > 56) {
    this._block.fill(0, this._blockOffset, 64)
    this._update()
    this._blockOffset = 0
  }

  this._block.fill(0, this._blockOffset, 56)
  this._block.writeUInt32LE(this._length[0], 56)
  this._block.writeUInt32LE(this._length[1], 60)
  this._update()

  // produce result
  var buffer = new Buffer(20)
  buffer.writeInt32LE(this._a, 0)
  buffer.writeInt32LE(this._b, 4)
  buffer.writeInt32LE(this._c, 8)
  buffer.writeInt32LE(this._d, 12)
  buffer.writeInt32LE(this._e, 16)
  return buffer
}

function rotl(x, n) {
  return (x << n) | (x >>> (32 - n))
}

function fn1(a, b, c, d, e, m, k, s) {
  return (rotl((a + (b ^ c ^ d) + m + k) | 0, s) + e) | 0
}

function fn2(a, b, c, d, e, m, k, s) {
  return (rotl((a + ((b & c) | ((~b) & d)) + m + k) | 0, s) + e) | 0
}

function fn3(a, b, c, d, e, m, k, s) {
  return (rotl((a + ((b | (~c)) ^ d) + m + k) | 0, s) + e) | 0
}

function fn4(a, b, c, d, e, m, k, s) {
  return (rotl((a + ((b & d) | (c & (~d))) + m + k) | 0, s) + e) | 0
}

function fn5(a, b, c, d, e, m, k, s) {
  return (rotl((a + (b ^ (c | (~d))) + m + k) | 0, s) + e) | 0
}

console.log(new RIPEMD160().update('abc').digest('hex'))

參考至https://www.esat.kuleuven.be/cosic/publications/article-317.pdf