本文实例讲述了JavaScript实现SHA-1加密算法的方法。分享给大家供大家参考。具体实现方法如下：
调用方法：hex_sha1即可。
/*
*
* 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;
}
希望本文所述对大家的javascript程序设计有所帮助。
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