js实现sha1加密算法

在实现页面通过js调用微信客户端扫码的api的时候需要用到sha1签名算法，所以在网上找了一圈，以下代码可用，直接调用hex_sha1就可以了
var hexcase = 0; /* hex output format. 0 - lowercase; 1 - uppercase */
var chrsz = 8; /* bits per input character. 8 - ASCII; 16 - Unicode */
/*
*
* The main function to calculate message digest
*
*/
function hex_sha1(s){

        return binb2hex(core_sha1(AlignSHA1(s)));

    }



    /*
     *
     * Calculate the SHA-1 of an array of big-endian words, and a bit length
     *
     */
    function core_sha1(blockArray){

        var x = blockArray; // append padding
        var w = Array(80);

        var a = 1732584193;

        var b = -271733879;

        var c = -1732584194;

        var d = 271733878;

        var e = -1009589776;

        for (var i = 0; i < x.length; i += 16) // 每次处理512位 16*32
        {

            var olda = a;

            var oldb = b;

            var oldc = c;

            var oldd = d;

            var olde = e;

            for (var j = 0; j < 80; j++) // 对每个512位进行80步操作
            {

                if (j < 16) 
                    w[j] = x[i + j];

                else
                    w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1);

                var t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)), safe_add(safe_add(e, w[j]), sha1_kt(j)));

                e = d;

                d = c;

                c = rol(b, 30);

                b = a;

                a = t;

            }

            a = safe_add(a, olda);

            b = safe_add(b, oldb);

            c = safe_add(c, oldc);

            d = safe_add(d, oldd);

            e = safe_add(e, olde);

        }

        return new Array(a, b, c, d, e);

    }

    /*
     *
     * Perform the appropriate triplet combination function for the current
     * iteration
     *
     * 返回对应F函数的值
     *
     */
    function sha1_ft(t, b, c, d){

        if (t < 20) 
            return (b & c) | ((~ b) & d);

        if (t < 40) 
            return b ^ c ^ d;

        if (t < 60) 
            return (b & c) | (b & d) | (c & d);

        return b ^ c ^ d; // t<80
    }

    /*
     *
     * Determine the appropriate additive constant for the current iteration
     *
     * 返回对应的Kt值
     *
     */
    function sha1_kt(t){

        return (t < 20) ? 1518500249 : (t < 40) ? 1859775393 : (t < 60) ? -1894007588 : -899497514;

    }

    /*
     *
     * Add integers, wrapping at 2^32. This uses 16-bit operations internally
     *
     * to work around bugs in some JS interpreters.
     *
     * 将32位数拆成高16位和低16位分别进行相加，从而实现 MOD 2^32 的加法
     *
     */
    function safe_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.
     *
     * 32位二进制数循环左移
     *
     */
    function rol(num, cnt){

        return (num << cnt) | (num >>> (32 - cnt));

    }

    /*
     *
     * The standard SHA1 needs the input string to fit into a block
     *
     * This function align the input string to meet the requirement
     *
     */
    function AlignSHA1(str){

        var nblk = ((str.length + 8) >> 6) + 1, blks = new Array(nblk * 16);

        for (var i = 0; i < nblk * 16; i++) 
            blks[i] = 0;

        for (i = 0; i < str.length; i++) 

            blks[i >> 2] |= str.charCodeAt(i) << (24 - (i & 3) * 8);

        blks[i >> 2] |= 0x80 << (24 - (i & 3) * 8);

        blks[nblk * 16 - 1] = str.length * 8;

        return blks;

    }

    /*
     *
     * Convert an array of big-endian words to a hex string.
     *
     */
    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;

    }

    /*
     *
     * Perform a simple self-test to see if the VM is working
     *
     */
    function sha1_vm_test(){

        return hex_sha1("abc") == "a9993e364706816aba3e25717850c26c9cd0d89d";

    }