如何为给定字符串生成 32 个字节的 SHA256？

Question

我正在寻找 javascript 代码，用于为给定字符串 32 字节 生成 SHA256

这段代码应该可以在浏览器中运行，因此它应该可以在没有任何依赖的情况下运行

到目前为止，我发现了以下提供 64 字节 SHA256 的函数：

/**
* Secure Hash Algorithm (SHA256)
* http://www.webtoolkit.info/
* Original code by Angel Marin, Paul Johnston
**/

function SHA256(s){
 var chrsz = 8;
 var hexcase = 0;

 function safe_add (x, y) {
 var lsw = (x & 0xFFFF) + (y & 0xFFFF);
 var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
 return (msw << 16) | (lsw & 0xFFFF);
 }

 function S (X, n) { return ( X >>> n ) | (X << (32 - n)); }
 function R (X, n) { return ( X >>> n ); }
 function Ch(x, y, z) { return ((x & y) ^ ((~x) & z)); }
 function Maj(x, y, z) { return ((x & y) ^ (x & z) ^ (y & z)); }
 function Sigma0256(x) { return (S(x, 2) ^ S(x, 13) ^ S(x, 22)); }
 function Sigma1256(x) { return (S(x, 6) ^ S(x, 11) ^ S(x, 25)); }
 function Gamma0256(x) { return (S(x, 7) ^ S(x, 18) ^ R(x, 3)); }
 function Gamma1256(x) { return (S(x, 17) ^ S(x, 19) ^ R(x, 10)); }

 function core_sha256 (m, l) {
 var K = new Array(0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5, 0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5, 0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3, 0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174, 0xE49B69C1, 0xEFBE4786, 0xFC19DC6, 0x240CA1CC, 0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA, 0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7, 0xC6E00BF3, 0xD5A79147, 0x6CA6351, 0x14292967, 0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13, 0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85, 0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3, 0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070, 0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5, 0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3, 0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208, 0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2);
 var HASH = new Array(0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19);
 var W = new Array(64);
 var a, b, c, d, e, f, g, h, i, j;
 var T1, T2;

 m[l >> 5] |= 0x80 << (24 - l % 32);
 m[((l + 64 >> 9) << 4) + 15] = l;

 for ( var i = 0; i<m.length; i+=16 ) {
 a = HASH[0];
 b = HASH[1];
 c = HASH[2];
 d = HASH[3];
 e = HASH[4];
 f = HASH[5];
 g = HASH[6];
 h = HASH[7];

 for ( var j = 0; j<64; j++) {
 if (j < 16) W[j] = m[j + i];
 else W[j] = safe_add(safe_add(safe_add(Gamma1256(W[j - 2]), W[j - 7]), Gamma0256(W[j - 15])), W[j - 16]);

 T1 = safe_add(safe_add(safe_add(safe_add(h, Sigma1256(e)), Ch(e, f, g)), K[j]), W[j]);
 T2 = safe_add(Sigma0256(a), Maj(a, b, c));

 h = g;
 g = f;
 f = e;
 e = safe_add(d, T1);
 d = c;
 c = b;
 b = a;
 a = safe_add(T1, T2);
 }

 HASH[0] = safe_add(a, HASH[0]);
 HASH[1] = safe_add(b, HASH[1]);
 HASH[2] = safe_add(c, HASH[2]);
 HASH[3] = safe_add(d, HASH[3]);
 HASH[4] = safe_add(e, HASH[4]);
 HASH[5] = safe_add(f, HASH[5]);
 HASH[6] = safe_add(g, HASH[6]);
 HASH[7] = safe_add(h, HASH[7]);
 }
 return HASH;
 }

 function str2binb (str) {
 var bin = Array();
 var mask = (1 << chrsz) - 1;
 for(var i = 0; i < str.length * chrsz; i += chrsz) {
 bin[i>>5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - i % 32);
 }
 return bin;
 }

 function Utf8Encode(string) {
 string = string.replace(/\r\n/g,'\n');
 var utftext = '';

 for (var n = 0; n < string.length; n++) {

 var c = string.charCodeAt(n);

 if (c < 128) {
 utftext += String.fromCharCode(c);
 }
 else if((c > 127) && (c < 2048)) {
 utftext += String.fromCharCode((c >> 6) | 192);
 utftext += String.fromCharCode((c & 63) | 128);
 }
 else {
 utftext += String.fromCharCode((c >> 12) | 224);
 utftext += String.fromCharCode(((c >> 6) & 63) | 128);
 utftext += String.fromCharCode((c & 63) | 128);
 }

 }

 return utftext;
 }

 function binb2hex (binarray) {
 var hex_tab = hexcase ? '0123456789ABCDEF' : '0123456789abcdef';
 var str = '';
 for(var i = 0; i < binarray.length * 4; i++) {
 str += hex_tab.charAt((binarray[i>>2] >> ((3 - i % 4)*8+4)) & 0xF) +
 hex_tab.charAt((binarray[i>>2] >> ((3 - i % 4)*8 )) & 0xF);
 }
 return str;
 }

 s = Utf8Encode(s);
 return binb2hex(core_sha256(str2binb(s), s.length * chrsz));
}

Answer 1

您实际收到的结果是 32 个字节。

我们来看一个例子：

console.log(SHA256("test"));

returns:

9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08

我们看到的是一个 32 字节的字符串表示形式，它产生 64 字节的单个字符。然而，一组两个字符实际上是一个字节，十进制范围从 0 到 255。

9f (hex) -> 10011111 (binary) -> 159 (decimal)

86 (hex) -> 10000110 (binary) -> 134 (decimal)

等等。

如果要将 64 个字符序列存储为 'real' 32 个字节，则需要将两个字符对转换为一个 8 位无符号整数值 (0-255) 并将它们放在 JavaScript类型数组。

例如...

let hexString = "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08";
let unsignedIntegers = hexString.match(/[\dA-F]{2}/gi).map(function(s) {
  return parseInt(s, 16);
});
let typedArray = new Uint8Array(unsignedIntegers);
console.log(typedArray);

...给出一个 32 字节的 Uint8Array。

如何为给定字符串生成 32 个字节的 SHA256？

how to generate SHA256 with 32 bytes for a given string?

javascript

sha256