关于Digital Signature的一个演示？

用Jscript写成，虽然写的时候与原来有点出入吧，但是意思应该表达出来了。


var content = "Hello world.";

 

var Mykeys = {

    "Tom" : 4,

    "John" : 8

}

 

var Tomskey = 22;

var Johnskey = 18;

 

var Transmiting = "";

var Receive = "";

 

document.write("<br>The content is '" + content + "'. <br><br><br>");

 

Transmiting = enc(Mykeys["Tom"], content);

document.write("<br>I send tom a '" + Transmiting + "'.");

Receive = dec(Tomskey, Transmiting);

document.write("<br>Tom read a '" + Receive + "'.<br>");

 

Transmiting = enc(Mykeys["John"], content);

document.write("<br>I send John a '" + Transmiting + "'.");

Receive = dec(Johnskey, Transmiting);

document.write("<br>John read a '" + Receive + "'.<br>");

 

Transmiting = enc(Tomskey, content);

document.write("<br>Tom send me a '" + Transmiting + "'.");

Receive = dec(Mykeys["Tom"], Transmiting);

document.write("<br>I read a '" + Receive + "'.<br>");

 

Transmiting = enc(Johnskey, content);

document.write("<br>John send me a '" + Transmiting + "'.");

Receive = dec(Mykeys["John"], Transmiting);

document.write("<br>I read a '" + Receive + "'.<br>");

 

function enc(key, content)

{

    var theChars = content.split("");

 

    for (var i=0;i<theChars.length;i++)

       theChars[i] = String.fromCharCode(content.charCodeAt(i) + key);

 

    return theChars.join("");

}

 

function dec(key, content)

{

    var theChars = content.split("");

 

    for (var i=0;i<theChars.length;i++)

       theChars[i] = String.fromCharCode(content.charCodeAt(i) + key - 26);

 

    return theChars.join("");

}