信息安全概论
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}
