关于sha1加密与md5加密

1.区别

Hash，一般翻译做"散列"，也有直接音译为"哈希"的，就是把任意长度的输入，变换成固定长度的输出，该输出就是散列值。这种转换是一种压缩映射，也就是，散列值的空间通常远小于输入的空间，不同的输入可能会散列成相同的输出，而不可能从散列值来唯一的确定输入值。简单的说就是一种将任意长度的消息压缩到某一固定长度的消息摘要的函数。
MD5与SHA1都是Hash算法，MD5输出是128位的，SHA1输出是160位的，MD5比SHA1快，SHA1比MD5强度高。

Hash是一种特殊的算法，MD5就是其中常用的一种。它的算法的特征是不可逆性，并且才计算的时候所有的数据都参与了运算，其中任何一个数据变化了都会导致计算出来的Hash值完全不同，所以通常用来校验数据是否正确或用作身份验证。常见的，论坛里面用户的密码是经过MD5等Hash算法算出来的Hash值进行保存的。

2.sha1

调用：

hex_sha1("abc")

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;

     var oldd = d;

     var olde = e;

     for(var j = 0; j < 80; j++)

     {

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

 }

 /*

 * Perform the appropriate triplet combination function for the current

 * iteration

 */

 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;

 }

 /*

 * Determine the appropriate additive constant for the current iteration

 */

 function sha1_kt(t)

 {

   return (t < 20) ?  1518500249 : (t < 40) ?  1859775393 :

          (t < 60) ? -1894007588 : -899497514;

 }

 /*

 * Calculate the HMAC-SHA1 of a key and some data

 */

 function core_hmac_sha1(key, data)

 {

   var bkey = str2binb(key);

   if(bkey.length > 16) bkey = core_sha1(bkey, key.length * chrsz);

   var ipad = Array(16), opad = Array(16);

   for(var i = 0; i < 16; i++)

   {

     ipad[i] = bkey[i] ^ 0x36363636;

     opad[i] = bkey[i] ^ 0x5C5C5C5C;

   }

   var hash = core_sha1(ipad.concat(str2binb(data)), 512 + data.length * chrsz);

   return core_sha1(opad.concat(hash), 512 + 160);

 }

 /*

 * Add integers, wrapping at 2^32. This uses 16-bit operations internally

 * to work around bugs in some JS interpreters.

 */

 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.

 */

 function rol(num, cnt)

 {

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

 }

 /*

 * Convert an 8-bit or 16-bit string to an array of big-endian words

 * In 8-bit function, characters >255 have their hi-byte silently ignored.

 */

 function str2binb(str)

 {

   var bin = Array();

   var mask = (1 << chrsz) - 1;

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

     bin[i>>5] |= (str.charCodeAt(i / chrsz) & mask) << (32 - chrsz - i%32);

   return bin;

 }

 /*

 * Convert an array of big-endian words to a string

 */

 function binb2str(bin)

 {

   var str = "";

   var mask = (1 << chrsz) - 1;

   for(var i = 0; i < bin.length * 32; i += chrsz)

     str += String.fromCharCode((bin[i>>5] >>> (32 - chrsz - i%32)) & mask);

   return str;

 }

 /*

 * 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;

 }

 /*

 * Convert an array of big-endian words to a base-64 string

 */

 function binb2b64(binarray)

 {

   var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

   var str = "";

   for(var i = 0; i < binarray.length * 4; i += 3)

   {

     var triplet = (((binarray[i   >> 2] >> 8 * (3 -  i   %4)) & 0xFF) << 16)

                 | (((binarray[i+1 >> 2] >> 8 * (3 - (i+1)%4)) & 0xFF) << 8 )

                 |  ((binarray[i+2 >> 2] >> 8 * (3 - (i+2)%4)) & 0xFF);

     for(var j = 0; j < 4; j++)

     {

       if(i * 8 + j * 6 > binarray.length * 32) str += b64pad;

       else str += tab.charAt((triplet >> 6*(3-j)) & 0x3F);

     }

   }

   return str;

 }

3.md5

js调用：

hex_md5("abc")