/*  *  * A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined  * in FIPS PUB 180-1  *  * By lizq  *  * 2006-11-11  *  */ /*  *  * Configurable variables.  *  */ 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))); } /*  *  * Perform a simple self-test to see if the VM is working  *  */ function sha1_vm_test(){     return hex_sha1("abc") == "a9993e364706816aba3e25717850c26c9cd0d89d"; } /*  *  * 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; } /*  *  * calculate MessageDigest accord to source message that inputted  *  */ function calcDigest(){     var digestM = hex_sha1(document.SHAForm.SourceMessage.value);     document.SHAForm.MessageDigest.value = digestM; }