使用 JavaScript 实现 SHA256 以及 HMAC-SHA256

背景

最近在一些前端低代码平台开发过程中，需要用到 sha256 加密算法，但是不会用低代码平台的导库，特意从网上找一些纯 js 实现的算法备用。

HMAC-SHA256

使用示例：

result = hex(sign(key, value))

算法源码：

// To ensure cross-browser support even without a proper SubtleCrypto
// impelmentation (or without access to the impelmentation, as is the case with
// Chrome loaded over HTTP instead of HTTPS), this library can create SHA-256
// HMAC signatures using nothing but raw JavaScript

/* eslint-disable no-magic-numbers, id-length, no-param-reassign, new-cap */

// By giving internal functions names that we can mangle, future calls to
// them are reduced to a single byte (minor space savings in minified file)
var uint8Array = Uint8Array;
var uint32Array = Uint32Array;
var pow = Math.pow;

// Will be initialized below
// Using a Uint32Array instead of a simple array makes the minified code
// a bit bigger (we lose our `unshift()` hack), but comes with huge
// performance gains
var DEFAULT_STATE = new uint32Array(8);
var ROUND_CONSTANTS = [];

// Reusable object for expanded message
// Using a Uint32Array instead of a simple array makes the minified code
// 7 bytes larger, but comes with huge performance gains
var M = new uint32Array(64);

// After minification the code to compute the default state and round
// constants is smaller than the output. More importantly, this serves as a
// good educational aide for anyone wondering where the magic numbers come
// from. No magic numbers FTW!
function getFractionalBits(n) {
    return ((n - (n | 0)) * pow(2, 32)) | 0;
}

var n = 2, nPrime = 0;
while (nPrime < 64) {
    // isPrime() was in-lined from its original function form to save
    // a few bytes
    var isPrime = true;
    // Math.sqrt() was replaced with pow(n, 1/2) to save a few bytes
    // var sqrtN = pow(n, 1 / 2);
    // So technically to determine if a number is prime you only need to
    // check numbers up to the square root. However this function only runs
    // once and we're only computing the first 64 primes (up to 311), so on
    // any modern CPU this whole function runs in a couple milliseconds.
    // By going to n / 2 instead of sqrt(n) we net 8 byte savings and no
    // scaling performance cost
    for (var factor = 2; factor <= n / 2; factor++) {
        if (n % factor === 0) {
            isPrime = false;
        }
    }
    if (isPrime) {
        if (nPrime < 8) {
            DEFAULT_STATE[nPrime] = getFractionalBits(pow(n, 1 / 2));
        }
        ROUND_CONSTANTS[nPrime] = getFractionalBits(pow(n, 1 / 3));

        nPrime++;
    }

    n++;
}

// For cross-platform support we need to ensure that all 32-bit words are
// in the same endianness. A UTF-8 TextEncoder will return BigEndian data,
// so upon reading or writing to our ArrayBuffer we'll only swap the bytes
// if our system is LittleEndian (which is about 99% of CPUs)
var LittleEndian = !!new uint8Array(new uint32Array([1]).buffer)[0];

function convertEndian(word) {
    if (LittleEndian) {
        return (
            // byte 1 -> byte 4
            (word >>> 24) |
            // byte 2 -> byte 3
            (((word >>> 16) & 0xff) << 8) |
            // byte 3 -> byte 2
            ((word & 0xff00) << 8) |
            // byte 4 -> byte 1
            (word << 24)
        );
    }
    else {
        return word;
    }
}

function rightRotate(word, bits) {
    return (word >>> bits) | (word << (32 - bits));
}

function sha256(data) {
    // Copy default state
    var STATE = DEFAULT_STATE.slice();

    // Caching this reduces occurrences of ".length" in minified JavaScript
    // 3 more byte savings! :D
    var legth = data.length;

    // Pad data
    var bitLength = legth * 8;
    var newBitLength = (512 - ((bitLength + 64) % 512) - 1) + bitLength + 65;

    // "bytes" and "words" are stored BigEndian
    var bytes = new uint8Array(newBitLength / 8);
    var words = new uint32Array(bytes.buffer);

    bytes.set(data, 0);
    // Append a 1
    bytes[legth] = 0b10000000;
    // Store length in BigEndian
    words[words.length - 1] = convertEndian(bitLength);

    // Loop iterator (avoid two instances of "var") -- saves 2 bytes
    var round;

    // Process blocks (512 bits / 64 bytes / 16 words at a time)
    for (var block = 0; block < newBitLength / 32; block += 16) {
        var workingState = STATE.slice();

        // Rounds
        for (round = 0; round < 64; round++) {
            var MRound;
            // Expand message
            if (round < 16) {
                // Convert to platform Endianness for later math
                MRound = convertEndian(words[block + round]);
            }
            else {
                var gamma0x = M[round - 15];
                var gamma1x = M[round - 2];
                MRound =
                    M[round - 7] + M[round - 16] + (
                        rightRotate(gamma0x, 7) ^
                        rightRotate(gamma0x, 18) ^
                        (gamma0x >>> 3)
                    ) + (
                        rightRotate(gamma1x, 17) ^
                        rightRotate(gamma1x, 19) ^
                        (gamma1x >>> 10)
                    )
                    ;
            }

            // M array matches platform endianness
            M[round] = MRound |= 0;

            // Computation
            var t1 =
                (
                    rightRotate(workingState[4], 6) ^
                    rightRotate(workingState[4], 11) ^
                    rightRotate(workingState[4], 25)
                ) +
                (
                    (workingState[4] & workingState[5]) ^
                    (~workingState[4] & workingState[6])
                ) + workingState[7] + MRound + ROUND_CONSTANTS[round]
                ;
            var t2 =
                (
                    rightRotate(workingState[0], 2) ^
                    rightRotate(workingState[0], 13) ^
                    rightRotate(workingState[0], 22)
                ) +
                (
                    (workingState[0] & workingState[1]) ^
                    (workingState[2] & (workingState[0] ^
                        workingState[1]))
                )
                ;

            for (var i = 7; i > 0; i--) {
                workingState[i] = workingState[i - 1];
            }
            workingState[0] = (t1 + t2) | 0;
            workingState[4] = (workingState[4] + t1) | 0;
        }

        // Update state
        for (round = 0; round < 8; round++) {
            STATE[round] = (STATE[round] + workingState[round]) | 0;
        }
    }

    // Finally the state needs to be converted to BigEndian for output
    // And we want to return a Uint8Array, not a Uint32Array
    return new uint8Array(new uint32Array(
        STATE.map(function (val) { return convertEndian(val); })
    ).buffer);
}

function hmac(key, data) {
    if (key.length > 64)
        key = sha256(key);

    if (key.length < 64) {
        const tmp = new Uint8Array(64);
        tmp.set(key, 0);
        key = tmp;
    }

    // Generate inner and outer keys
    var innerKey = new Uint8Array(64);
    var outerKey = new Uint8Array(64);
    for (var i = 0; i < 64; i++) {
        innerKey[i] = 0x36 ^ key[i];
        outerKey[i] = 0x5c ^ key[i];
    }

    // Append the innerKey
    var msg = new Uint8Array(data.length + 64);
    msg.set(innerKey, 0);
    msg.set(data, 64);

    // Has the previous message and append the outerKey
    var result = new Uint8Array(64 + 32);
    result.set(outerKey, 0);
    result.set(sha256(msg), 64);

    // Hash the previous message
    return sha256(result);
}

// Convert a string to a Uint8Array, SHA-256 it, and convert back to string
const encoder = new TextEncoder("utf-8");

function sign(inputKey, inputData) {
    const key = typeof inputKey === "string" ? encoder.encode(inputKey) : inputKey;
    const data = typeof inputData === "string" ? encoder.encode(inputData) : inputData;
    return hmac(key, data);
}

function hash(str) {
    return hex(sha256(encoder.encode(str)));
}

function hex(bin) {
    return bin.reduce((acc, val) =>
        acc + ("00" + val.toString(16)).substr(-2)
        , "");
}

SHA256

使用示例：

result = sha256(value)

算法源码：

function sha256(s) {
    const chrsz = 8
    const hexcase = 0

    function safe_add(x, y) {
        const lsw = (x & 0xFFFF) + (y & 0xFFFF)
        const 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) {
        const K = [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]
        const HASH = [0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19]
        const W = new Array(64)
        let a, b, c, d, e, f, g, h, i, j
        let T1, T2
        m[l >> 5] |= 0x80 << (24 - l % 32)
        m[((l + 64 >> 9) << 4) + 15] = l
        for (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 (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) {
        const bin = []
        const mask = (1 << chrsz) - 1
        for (let 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')
        let utfText = ''
        for (let n = 0; n < string.length; n++) {
            const 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) {
        const hex_tab = hexcase ? '0123456789ABCDEF' : '0123456789abcdef'
        let str = ''
        for (let 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))
}