javascript将url中的参数加密解密代码

<SCRIPT LANGUAGE="JavaScript">    

<!-- Begin    

function Encrypt(str, pwd) {    

    if(str=="")return "";    

    str = escape(str);    

    if(!pwd || pwd==""){ var pwd="1234"; }    

    pwd = escape(pwd);    

      if(pwd == null || pwd.length <= 0) {    

        alert("Please enter a password with which to encrypt the message.");    

          return null;    

      }    

      var prand = "";    

      for(var I=0; I<pwd.length; I++) {    

        prand += pwd.charCodeAt(I).toString();    

      }    

      var sPos = Math.floor(prand.length / 5);    

      var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos*2) + prand.charAt(sPos*3) + prand.charAt(sPos*4) + prand.charAt(sPos*5));    

      var incr = Math.ceil(pwd.length / 2);    

      var modu = Math.pow(2, 31) - 1;    

      if(mult < 2) {    

        alert("Algorithm cannot find a suitable hash. Please choose a different password. /nPossible considerations are to choose a more complex or longer password.");    

        return null;    

      }    

      var salt = Math.round(Math.random() * 1000000000) % 100000000;    

      prand += salt;    

      while(prand.length > 10) {    

        prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString();    

      }    

      prand = (mult * prand + incr) % modu;    

    var enc_chr = "";    

    var enc_str = "";    

    for(var I=0; I<str.length; I++) {    

        enc_chr = parseInt(str.charCodeAt(I) ^ Math.floor((prand / modu) * 255));    

        if(enc_chr < 16) {    

            enc_str += "0" + enc_chr.toString(16);    

        }else    

            enc_str += enc_chr.toString(16);    

        prand = (mult * prand + incr) % modu;    

    }    

      salt = salt.toString(16);    

      while(salt.length < 8)salt = "0" + salt;    

    enc_str += salt;    

    return enc_str;    

}    

function Decrypt(str, pwd) {    

    if(str=="")return "";    

    if(!pwd || pwd==""){ var pwd="1234"; }    

    pwd = escape(pwd);    

      if(str == null || str.length < 8) {    

        alert("A salt value could not be extracted from the encrypted message because it's length is too short. The message cannot be decrypted.");    

        return;    

      }    

      if(pwd == null || pwd.length <= 0) {    

        alert("Please enter a password with which to decrypt the message.");    

        return;    

      }    

      var prand = "";    

      for(var I=0; I<pwd.length; I++) {    

        prand += pwd.charCodeAt(I).toString();    

      }    

      var sPos = Math.floor(prand.length / 5);    

      var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos*2) + prand.charAt(sPos*3) + prand.charAt(sPos*4) + prand.charAt(sPos*5));    

      var incr = Math.round(pwd.length / 2);    

      var modu = Math.pow(2, 31) - 1;    

      var salt = parseInt(str.substring(str.length - 8, str.length), 16);    

      str = str.substring(0, str.length - 8);    

      prand += salt;    

      while(prand.length > 10) {    

        prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString();    

      }    

      prand = (mult * prand + incr) % modu;    

      var enc_chr = "";    

      var enc_str = "";    

    for(var I=0; I<str.length; I+=2) {    

        enc_chr = parseInt(parseInt(str.substring(I, I+2), 16) ^ Math.floor((prand / modu) * 255));    

        enc_str += String.fromCharCode(enc_chr);    

        prand = (mult * prand + incr) % modu;    

    }    

    return unescape(enc_str);    

}    

//  End -->    

</script>