JavaScript实现MD5和SHA-1加密：安全用户登录示例

在一般网站开发中,用户登陆的密码都是明码发送的,这样是很不安全的.   
解决方法:在提交前,用JavaScript将用户密码进行sha1或md5加密.下面是js源码:   
  
/*sha1  
* A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined  
* in FIPS PUB 180-1  
* Version 2.1a Copyright Paul Johnston 2000 - 2002.  
* Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet  
* Distributed under the BSD License  
* See http://pajhome.org.uk/crypt/md5 for details.  
*/  
  
/*  
* Configurable variables. You may need to tweak these to be compatible with  
* the server-side, but the defaults work in most cases.  
*/  
var hexcase = 0; /* hex output format. 0 - lowercase; 1 - uppercase        */  
var b64pad = ""; /* base-64 pad character. "=" for strict RFC compliance   */  
var chrsz   = 8; /* bits per input character. 8 - ASCII; 16 - Unicode      */  
  
/*  
* These are the functions you'll usually want to call  
* They take string arguments and return either hex or base-64 encoded strings  
*/  
function hex_sha1(s){return binb2hex(core_sha1(str2binb(s),s.length * chrsz));}   
function b64_sha1(s){return binb2b64(core_sha1(str2binb(s),s.length * chrsz));}   
function str_sha1(s){return binb2str(core_sha1(str2binb(s),s.length * chrsz));}   
function hex_hmac_sha1(key, data){ return binb2hex(core_hmac_sha1(key, data));}   
function b64_hmac_sha1(key, data){ return binb2b64(core_hmac_sha1(key, data));}   
function str_hmac_sha1(key, data){ return binb2str(core_hmac_sha1(key, data));}   

  
/*  
* 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(x, len)   
{   
/* append padding */  
x[len >> 5] |= 0x80 << (24 - len % 32);   
x[((len + 64 >> 9) << 4) + 15] = len;   
  
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)   
{   
    var olda = a;   
    var oldb = b;   
    var oldc = c;