<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>字符串加密</title>
</head>
<body>
<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 baidu.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>
</body>
</html>
来源：https://www.cnblogs.com/movemoon/p/4754965.html