带密钥的加解密

代码如下：
<SCRIPT LANGUAGE="JavaScript"> <!-- Begin function encrypt(str, 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 == 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 enc_str; } // End --> </script> <form name="box"><center> <table cellpadding=0 cellspacing=0 border=0><tr><td colspan=3> <textarea cols=40 rows=5 wrap=virtual name=ipt>Welcome to jzzy.com</textarea> </td></tr> <tr height=50><td valign="top"> <input type="button" onclick="document.box.opt.value= encrypt(document.box.ipt.value, document.box.pwd.value);" value="加密"> </td><td align="center" valign="center"> <input type="text" name="pwd" value="password"> </td><td align="right" valign="bottom"> <input type="button" onclick="document.box.ipt.value= decrypt(document.box.opt.value, document.box.pwd.value);" value="解密"> </td></tr> <tr><td colspan=3> <textarea cols=40 rows=5 wrap=virtual name=opt></textarea> </td></tr></table> </center> </form>
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