javascript - PHP 的 `hex2bin` 的 Node.js/JS 实现返回错误结果。如何得到相同的结果？

Question

这是一段 PHP 代码:

$h = hex2bin('db6dc3f86800da4f7c19e643e8941ebb');
$md5 = md5($h);
echo $md5; // ==> b885730327999e8823d113161c3538d3

这在 Node.js 中也是一样的。但结果不同:

let h = hex2bin('db6dc3f86800da4f7c19e643e8941ebb');
let md5 = crypto.createHash('md5').update(h).digest('hex');
console.log(md5); ==> // a141519bf4b0acf2221ed94e721ddc7d

我使用了四种不同的 hex2bin JS 类似物变体，我可以在互联网上找到这些变体。它们都不会返回与 PHP 相同的结果。但不仅如此，这些 JS 函数都不会返回与其他 JS 函数相同的结果。

1. 从这里 http://locutus.io/php/strings/hex2bin/
2. 来自这个答案https://stackoverflow.com/a/12987042/1114926
3. 来自这个答案https://stackoverflow.com/a/41550641/1114926
4. 来自这个答案https://stackoverflow.com/a/17224848/1114926

为什么会这样？ PHP的hex2bin在JS/Node.js中真的不行吗？我是否需要为这个功能设置整个 PHP 解释器？

Answer 1

经过一段时间在网络上的挖掘，我终于找到了适合您的解决方案。我认为问题出在 javascript 的 md5 实现中，因为我在网上找到的大多数 hex2bin javascript 函数总是返回相同的结果。

这个 MD5 我发现 here 的 javascript 实现。如您所见，hex2bin 实现非常短，您可以在很多地方找到它。

/*

    MD5 IMPLEMENTATION

*/

var hex_chr = "0123456789abcdef";

function rhex(num) {
  str = "";
  for (j = 0; j <= 3; j++)
    str += hex_chr.charAt((num >> (j * 8 + 4)) & 0x0F) +
    hex_chr.charAt((num >> (j * 8)) & 0x0F);
  return str;
}

/*
 * Convert a string to a sequence of 16-word blocks, stored as an array.
 * Append padding bits and the length, as described in the MD5 standard.
 */
function str2blks_MD5(str) {
  nblk = ((str.length + 8) >> 6) + 1;
  blks = new Array(nblk * 16);
  for (i = 0; i < nblk * 16; i++) blks[i] = 0;
  for (i = 0; i < str.length; i++)
    blks[i >> 2] |= str.charCodeAt(i) << ((i % 4) * 8);
  blks[i >> 2] |= 0x80 << ((i % 4) * 8);
  blks[nblk * 16 - 2] = str.length * 8;
  return blks;
}

/*
 * Add integers, wrapping at 2^32. This uses 16-bit operations internally 
 * to work around bugs in some JS interpreters.
 */
function add(x, y) {
  var lsw = (x & 0xFFFF) + (y & 0xFFFF);
  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
  return (msw << 16) | (lsw & 0xFFFF);
}

/*
 * Bitwise rotate a 32-bit number to the left
 */
function rol(num, cnt) {
  return (num << cnt) | (num >>> (32 - cnt));
}

/*
 * These functions implement the basic operation for each round of the
 * algorithm.
 */
function cmn(q, a, b, x, s, t) {
  return add(rol(add(add(a, q), add(x, t)), s), b);
}

function ff(a, b, c, d, x, s, t) {
  return cmn((b & c) | ((~b) & d), a, b, x, s, t);
}

function gg(a, b, c, d, x, s, t) {
  return cmn((b & d) | (c & (~d)), a, b, x, s, t);
}

function hh(a, b, c, d, x, s, t) {
  return cmn(b ^ c ^ d, a, b, x, s, t);
}

function ii(a, b, c, d, x, s, t) {
  return cmn(c ^ (b | (~d)), a, b, x, s, t);
}

/*
 * Take a string and return the hex representation of its MD5.
 */
function calcMD5(str) {
  x = str2blks_MD5(str);
  a = 1732584193;
  b = -271733879;
  c = -1732584194;
  d = 271733878;

  for (i = 0; i < x.length; i += 16) {
    olda = a;
    oldb = b;
    oldc = c;
    oldd = d;

    a = ff(a, b, c, d, x[i + 0], 7, -680876936);
    d = ff(d, a, b, c, x[i + 1], 12, -389564586);
    c = ff(c, d, a, b, x[i + 2], 17, 606105819);
    b = ff(b, c, d, a, x[i + 3], 22, -1044525330);
    a = ff(a, b, c, d, x[i + 4], 7, -176418897);
    d = ff(d, a, b, c, x[i + 5], 12, 1200080426);
    c = ff(c, d, a, b, x[i + 6], 17, -1473231341);
    b = ff(b, c, d, a, x[i + 7], 22, -45705983);
    a = ff(a, b, c, d, x[i + 8], 7, 1770035416);
    d = ff(d, a, b, c, x[i + 9], 12, -1958414417);
    c = ff(c, d, a, b, x[i + 10], 17, -42063);
    b = ff(b, c, d, a, x[i + 11], 22, -1990404162);
    a = ff(a, b, c, d, x[i + 12], 7, 1804603682);
    d = ff(d, a, b, c, x[i + 13], 12, -40341101);
    c = ff(c, d, a, b, x[i + 14], 17, -1502002290);
    b = ff(b, c, d, a, x[i + 15], 22, 1236535329);

    a = gg(a, b, c, d, x[i + 1], 5, -165796510);
    d = gg(d, a, b, c, x[i + 6], 9, -1069501632);
    c = gg(c, d, a, b, x[i + 11], 14, 643717713);
    b = gg(b, c, d, a, x[i + 0], 20, -373897302);
    a = gg(a, b, c, d, x[i + 5], 5, -701558691);
    d = gg(d, a, b, c, x[i + 10], 9, 38016083);
    c = gg(c, d, a, b, x[i + 15], 14, -660478335);
    b = gg(b, c, d, a, x[i + 4], 20, -405537848);
    a = gg(a, b, c, d, x[i + 9], 5, 568446438);
    d = gg(d, a, b, c, x[i + 14], 9, -1019803690);
    c = gg(c, d, a, b, x[i + 3], 14, -187363961);
    b = gg(b, c, d, a, x[i + 8], 20, 1163531501);
    a = gg(a, b, c, d, x[i + 13], 5, -1444681467);
    d = gg(d, a, b, c, x[i + 2], 9, -51403784);
    c = gg(c, d, a, b, x[i + 7], 14, 1735328473);
    b = gg(b, c, d, a, x[i + 12], 20, -1926607734);

    a = hh(a, b, c, d, x[i + 5], 4, -378558);
    d = hh(d, a, b, c, x[i + 8], 11, -2022574463);
    c = hh(c, d, a, b, x[i + 11], 16, 1839030562);
    b = hh(b, c, d, a, x[i + 14], 23, -35309556);
    a = hh(a, b, c, d, x[i + 1], 4, -1530992060);
    d = hh(d, a, b, c, x[i + 4], 11, 1272893353);
    c = hh(c, d, a, b, x[i + 7], 16, -155497632);
    b = hh(b, c, d, a, x[i + 10], 23, -1094730640);
    a = hh(a, b, c, d, x[i + 13], 4, 681279174);
    d = hh(d, a, b, c, x[i + 0], 11, -358537222);
    c = hh(c, d, a, b, x[i + 3], 16, -722521979);
    b = hh(b, c, d, a, x[i + 6], 23, 76029189);
    a = hh(a, b, c, d, x[i + 9], 4, -640364487);
    d = hh(d, a, b, c, x[i + 12], 11, -421815835);
    c = hh(c, d, a, b, x[i + 15], 16, 530742520);
    b = hh(b, c, d, a, x[i + 2], 23, -995338651);

    a = ii(a, b, c, d, x[i + 0], 6, -198630844);
    d = ii(d, a, b, c, x[i + 7], 10, 1126891415);
    c = ii(c, d, a, b, x[i + 14], 15, -1416354905);
    b = ii(b, c, d, a, x[i + 5], 21, -57434055);
    a = ii(a, b, c, d, x[i + 12], 6, 1700485571);
    d = ii(d, a, b, c, x[i + 3], 10, -1894986606);
    c = ii(c, d, a, b, x[i + 10], 15, -1051523);
    b = ii(b, c, d, a, x[i + 1], 21, -2054922799);
    a = ii(a, b, c, d, x[i + 8], 6, 1873313359);
    d = ii(d, a, b, c, x[i + 15], 10, -30611744);
    c = ii(c, d, a, b, x[i + 6], 15, -1560198380);
    b = ii(b, c, d, a, x[i + 13], 21, 1309151649);
    a = ii(a, b, c, d, x[i + 4], 6, -145523070);
    d = ii(d, a, b, c, x[i + 11], 10, -1120210379);
    c = ii(c, d, a, b, x[i + 2], 15, 718787259);
    b = ii(b, c, d, a, x[i + 9], 21, -343485551);

    a = add(a, olda);
    b = add(b, oldb);
    c = add(c, oldc);
    d = add(d, oldd);
  }
  return rhex(a) + rhex(b) + rhex(c) + rhex(d);
}


/*

    HEX2BIN IMPLEMENTATION

*/
function hex2bin(hex) {
  var bytes = [],
    str;

  for (var i = 0; i < hex.length - 1; i += 2)
    bytes.push(parseInt(hex.substr(i, 2), 16));

  return String.fromCharCode.apply(String, bytes);
}
var inputStr = 'db6dc3f86800da4f7c19e643e8941ebb';
var hex2bin = hex2bin(inputStr);
console.log('initial = ' + inputStr);
console.log('hex2bin = ' + hex2bin);
console.log('md5 = ' + calcMD5(hex2bin));