给大家分享一个JavaScript的SHA1（哈希算法）

//SHA1加密算法
function SHA1(msg) {
function rotate_left(n, s) {
var t4 = (n << s ) | (n >>> (32 - s));
return t4;
};
function lsb_hex(val) {
var str = "";
var i;
var vh;
var vl;


for ( i = 0; i <= 6; i += 2) {
vh = (val >>> (i * 4 + 4)) & 0x0f;
vl = (val >>> (i * 4)) & 0x0f;
str += vh.toString(16) + vl.toString(16);
}
return str;
};


function cvt_hex(val) {
var str = "";
var i;
var v;


for ( i = 7; i >= 0; i--) {
v = (val >>> (i * 4)) & 0x0f;
str += v.toString(16);
}
return str;
};


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;
};


var blockstart;
var i, j;
var W = new Array(80);
var H0 = 0x67452301;
var H1 = 0xEFCDAB89;
var H2 = 0x98BADCFE;
var H3 = 0x10325476;
var H4 = 0xC3D2E1F0;
var A, B, C, D, E;
var temp;


msg = Utf8Encode(msg);


var msg_len = msg.length;


var word_array = new Array();
for ( i = 0; i < msg_len - 3; i += 4) {
j = msg.charCodeAt(i) << 24 | msg.charCodeAt(i + 1) << 16 | msg.charCodeAt(i + 2) << 8 | msg.charCodeAt(i + 3);
word_array.push(j);
}


switch (msg_len % 4) {
case 0:
i = 0x080000000;
break;
case 1:
i = msg.charCodeAt(msg_len - 1) << 24 | 0x0800000;
break;


case 2:
i = msg.charCodeAt(msg_len - 2) << 24 | msg.charCodeAt(msg_len - 1) << 16 | 0x08000;
break;


case 3:
i = msg.charCodeAt(msg_len - 3) << 24 | msg.charCodeAt(msg_len - 2) << 16 | msg.charCodeAt(msg_len - 1) << 8 | 0x80;
break;
}


word_array.push(i);


while ((word_array.length % 16) != 14)
word_array.push(0);


word_array.push(msg_len >>> 29);
word_array.push((msg_len << 3) & 0x0ffffffff);


for ( blockstart = 0; blockstart < word_array.length; blockstart += 16) {


for ( i = 0; i < 16; i++)
W[i] = word_array[blockstart + i];
for ( i = 16; i <= 79; i++)
W[i] = rotate_left(W[i - 3] ^ W[i - 8] ^ W[i - 14] ^ W[i - 16], 1);


A = H0;
B = H1;
C = H2;
D = H3;
E = H4;


for ( i = 0; i <= 19; i++) {
temp = (rotate_left(A, 5) + ((B & C) | (~B & D)) + E + W[i] + 0x5A827999) & 0x0ffffffff;
E = D;
D = C;
C = rotate_left(B, 30);
B = A;
A = temp;
}


for ( i = 20; i <= 39; i++) {
temp = (rotate_left(A, 5) + (B ^ C ^ D) + E + W[i] + 0x6ED9EBA1) & 0x0ffffffff;
E = D;
D = C;
C = rotate_left(B, 30);
B = A;
A = temp;
}


for ( i = 40; i <= 59; i++) {
temp = (rotate_left(A, 5) + ((B & C) | (B & D) | (C & D)) + E + W[i] + 0x8F1BBCDC) & 0x0ffffffff;
E = D;
D = C;
C = rotate_left(B, 30);
B = A;
A = temp;
}


for ( i = 60; i <= 79; i++) {
temp = (rotate_left(A, 5) + (B ^ C ^ D) + E + W[i] + 0xCA62C1D6) & 0x0ffffffff;
E = D;
D = C;
C = rotate_left(B, 30);
B = A;
A = temp;
}


H0 = (H0 + A) & 0x0ffffffff;
H1 = (H1 + B) & 0x0ffffffff;
H2 = (H2 + C) & 0x0ffffffff;
H3 = (H3 + D) & 0x0ffffffff;
H4 = (H4 + E) & 0x0ffffffff;


}


var temp = cvt_hex(H0) + cvt_hex(H1) + cvt_hex(H2) + cvt_hex(H3) + cvt_hex(H4);


return temp.toLowerCase();
}