【JS加解密】凯撒密码加解密

【代码】

<!DOCTYPE html>
<html lang="utf-8">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<head>
     <title>凯撒加解密</title>
     </head>

     <body onload="main();">        
     </body>
</html>
<script type="text/javascript">
<!--
/*****************************************************************
* 用chrome浏览器打开执行，ctrl+shift+i看到执行结果。
******************************************************************/

// 可接受的字符
const SYMBOLS="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890 !?,.%'";

// 密钥
const KEY=7;

// 代码起始，由body_onload调用
function main(){
    console.log("密文="+encrypt("Life is not the amount of breath you take.It's the moments that take you breath away."));
    console.log("明文="+decrypt("SpmlApzAuv1A1olAhtv2u1AvmAiylh1oA6v2A1hrlEP1GzA1olAtvtlu1zA1oh1A1hrlA6v2Aiylh1oAh4h6E"));
};

// 加密字符串
function encrypt(message){
    var msg=message;

    var key=KEY;
    const SYM_LENGTH=SYMBOLS.length;
    var translated="";

    for(var i=0;i<msg.length;i++){
        var letter=msg.at(i);
        
        var idx=SYMBOLS.indexOf(letter);
        
        if (idx!=-1 ){
            translated+=SYMBOLS.at((idx+key)%SYM_LENGTH);
        }else{
            translated+=letter;
        }
    }

    return translated;
}

// 解密字符串
function decrypt(message){
    var msg=message;

    var key=KEY;
    const SYM_LENGTH=SYMBOLS.length;
    var translated="";

    for(var i=0;i<msg.length;i++){
        var letter=msg.at(i);
        
        var idx=SYMBOLS.indexOf(letter);
        
        if (idx!=-1 ){
            translated+=SYMBOLS.at((idx-key)%SYM_LENGTH);
        }else{
            translated+=letter;
        }
    }

    return translated;
}
//-->
</script>

【执行结果】

密文=SpmlApzAuv1A1olAhtv2u1AvmAiylh1oA6v2A1hrlEP1GzA1olAtvtlu1zA1oh1A1hrlA6v2Aiylh1oAh4h6E
明文=Life is not the amount of breath you take.It's the moments that take you breath away.

END

posted @ 2020-09-22 11:54  不朽的飞翔  阅读(155)  评论(0)    收藏  举报