这是一个PHP代码：
$h = hex2bin('db6dc3f86800da4f7c19e643e8941ebb');
$md5 = md5($h);
echo $md5; // ==> b885730327999e8823d113161c3538d3
这在Node.js中是一样的。但结果却不同：
let h = hex2bin('db6dc3f86800da4f7c19e643e8941ebb');
let md5 = crypto.createHash('md5').update(h).digest('hex');
console.log(md5); ==> // a141519bf4b0acf2221ed94e721ddc7d
我使用了hex2bin的四种不同的JS类似变体，我可以在互联网上找到它们。所有这些都不像PHP那样返回。但更重要的是，这些JS函数都没有返回与其他JS函数相同的结果。
为什么会这样？在JS / Node.js中使用PHP hex2bin真的不可能吗？我是否需要为这一功能设置整个PHP解释器？
答案 0 :(得分：1)
最后经过一段时间在网上挖掘后，我找到了正确的解决方案。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函数返回的结果总是相同。
此 MD5 javascript实施我发现 here 。正如您所看到的，hex2bin实现很短，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));