凯撒密码算法 Javascript实现

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原创最新推荐文章于 2026-04-03 02:43:41 发布 1.2k 阅读 AI 写同款· GEO 优化 ›

JavaScript，凯撒位移密码，算法位移密码算法挑战下面我们来介绍著名的凯撒密码Caesar cipher，又叫移位密码。移位密码也就是密码中的字母会按照指定的数量来做移位。一个常见的案例就是ROT13密码，字母会移位13个位置。由’A’ ↔ ‘N’, ‘B’ ↔’O’，以此类推。写一个ROT13函数，实现输入加密字符串，输出解密字符串。所有的字母都是大写，不要转化任何非字母形式的字符(例如：空格，标点符号)，遇到这些特殊... 阅读详情

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凯撒密码算法 ----Javascript实现

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>古典算法</title>
    <script src="./index.js"></script>
</head>
<body>
    <div class="all">
        <div class="one">
            <ul>
                <li class="first">
                    凯撒密码
                </li>
                <li> <span>输入密匙：</span> <input type="text" name="" id="secretKeyId"></li>
                <li> <span>输入明文：</span> <input type="text" name="" id="expressId"></li>
                <li> <span>输出密文：</span> <input type="text" name="" id="secretId" disabled></li>
                <li><button onclick="caesar()">加密</button> </li>
            </ul>
        </div>
    </div>
    <style>
        * {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        html,
        body,
        .all {
            height: 100%;
        }

        .all {
            position: relative;

        }

        .one {
            width: 270px;
            height: 150px;
            background-color: rgb(138, 138, 138, 0.5);
            position: absolute;
            left: 50%;
            top: 100px;
            transform: translate(-50%, -50%);
            border-radius: 10px;
        }


        span {
            display: inline-block;
            font-size: 10px;
        }


        .first {
            text-align: center;
            margin: 8px 0px;
        }

        li {
            padding: 0 10px;
        }

        li>button {
            float: right;
            margin-top: 15px;
            margin-right: 25px;
        }
    </style>
</body>

</html>

function caesar() {

    var secretKey, expressWords, secretWords;
    expressWords = document.getElementById("expressId").value;
    secretKey = document.getElementById("secretKeyId").value;
    //这里记得把拿到的密钥值从字符串类型转为Number类型
    secretKeyNum = Number(secretKey);

    var start1 = "A".charCodeAt(0);
    var end1 = "Z".charCodeAt(0);
    var start2 = "a".charCodeAt(0);
    var end2 = "z".charCodeAt(0);

    var strList = expressWords.split("");
    var judge, replace;
    for (var i = 0; i < expressWords.length; i++) {
        judge = strList[i].charCodeAt(0);
        if (judge <= end1 && judge >= start1) {
            replace = start1 + (judge - start1 + secretKeyNum) % 26;
            strList[i] = String.fromCharCode(replace);
        }
        else if (judge <= end2 && judge >= start2) {
            replace = start2 + (judge - start2 + secretKeyNum) % 26;
            strList[i] = String.fromCharCode(replace);
        }
    }
    secretWords = strList.join("");
    document.getElementById('secretId').value = secretWords
}