JavaScript实现AES算法加密和解密

JavaScript的加密和解密用的是google的CryptoJS库。本文以AES/ECB/NoPadding为例展示AES加密和解密的方法。

需要下载CryptoJS库，下载地址如下：
https://github.com/sytelus/CryptoJS

需要引入库文件：
<script src="./CryptoJS-master/rollups/aes.js"></script>
<script src="./CryptoJS-master/components/mode-ecb.js"></script>
<script src="./CryptoJS-master/components/pad-nopadding.js"></script>

加密方法：

function encrypt(str) {
    var decArray = hexStrToDecArray(str);
    var wordArray = int8parse(decArray);
    var encrypted = CryptoJS.AES.encrypt(wordArray, aesKeyBytes(), {
        mode: CryptoJS.mode.ECB,
        padding: CryptoJS.pad.NoPadding
    });
    return wordArrayToHexStr(encrypted.ciphertext.words);
}

这个方法传入的是十六进制字符串，格式为"AA BB CC DD EE FF"；
hexStrToDecArray()方法用来将十六进制字符串转换成十进制数字的数组；
int8parse()方法用来将十进制数字转换成CryptoJS所需要的wordArray数组；
最后，encrypt()方法加密得到的是一个wordArray数组，wordArrayToHexStr()再将其解析成十六进制字符串。

解密方法：

function decrypt(str) {
    var decArray = hexStrToDecArray(str);
    var wordArray = int8parse(decArray);
    var base64Str = CryptoJS.enc.Base64.stringify(wordArray);
    var decrypted = CryptoJS.AES.decrypt(base64Str, aesKeyBytes(), {
        mode: CryptoJS.mode.ECB,
        padding: CryptoJS.pad.NoPadding
    });
    return wordArrayToHexStr(decrypted.words);
}

解密方法同加密方法类似，但是CryptoJS.AES.decrypt()方法需要传入Base64格式的加密字符串，因此这里需要先使用CryptoJS.enc.Base64.stringify()方法做一次转换。

以下是完整的Demo代码：

<!DOCTYPE html>
<html>
<head>
<script src="./CryptoJS-master/rollups/aes.js"></script>
<script src="./CryptoJS-master/components/mode-ecb.js"></script>
<script src="./CryptoJS-master/components/pad-nopadding.js"></script>
<script>
function encryptText() {
    var plain = document.getElementById("plain").value;
    console.log("plain: " + plain);
    var encrypted = encrypt(plain);
    console.log("encrypted: " + encrypted);
    document.getElementById("encrypted").value = encrypted;
}

function decryptText() {
    var encrypted = document.getElementById("todecrypt").value;
    console.log("encrypted: " + encrypted);
    var decrypted = decrypt(encrypted);
    console.log("decrypted: " + decrypted);
    document.getElementById("decrypted").value = decrypted;
}

// 加解密用到的密钥
function aesKeyBytes() {
    var key_Int = new Int8Array([65, 144, 48, 53, 18, 52, 86, 120, 131, 116, 124, 139, 237, 203, 169, 135]);
    var keyBytes = int8parse(key_Int);
    return keyBytes;
}

// 十六进制字符串数组，个数如果不足16整数倍则补0
function hexTo16Hex(str) {
    var diff = 16 - (str.length + 1) / 3 % 16;
    for(var i = 0; i < diff; i++) {
        str = str + " 00";
    }
    return str;
}

// AES加密
function encrypt(str) {
    var decArray = hexStrToDecArray(str);
    var wordArray = int8parse(decArray);
    var encrypted = CryptoJS.AES.encrypt(wordArray, aesKeyBytes(), {
        mode: CryptoJS.mode.ECB,
        padding: CryptoJS.pad.NoPadding
    });
    return wordArrayToHexStr(encrypted.ciphertext.words);
}

// AES解密
function decrypt(str) {
    var decArray = hexStrToDecArray(str);
    var wordArray = int8parse(decArray);
    var base64Str = CryptoJS.enc.Base64.stringify(wordArray);
    var decrypted = CryptoJS.AES.decrypt(base64Str, aesKeyBytes(), {
        mode: CryptoJS.mode.ECB,
        padding: CryptoJS.pad.NoPadding
    });
    return wordArrayToHexStr(decrypted.words);
}

// 构建WordArray对象
function int8parse(u8arr) {
  var len = u8arr.length;
  var words = [];
  for (var i = 0; i < len; i++) {
      words[i >>> 2] |= (u8arr[i] & 0xff) << (24 - (i % 4) * 8);
  }
  return CryptoJS.lib.WordArray.create(words, len);
}

// 十六进制字符串(空格分割)转成十进制数字的数组
function hexStrToDecArray(str) {
    var strArray = str.split(" ");
    var decArray = [];
    for(var i = 0; i < strArray.length; i++) {
        decArray.push(parseInt(strArray[i], 16));
    }
    return arrayTo16Array(decArray);
}

// 十进制数组转成十六进制字符串
function decArrayToHexStr(array) {
    var hexStr = "";
    for(var i = 0; i < array.length; i++) {
        var str = array[i].toString(16).toUpperCase();
        if (str.length < 2) {
            str = "0" + str;
        }
        hexStr = hexStr + str + " ";
    }
    return hexStr.substr(0, hexStr.length - 1);
}

// word类型的十进制数组转成十六进制字符串
function wordArrayToHexStr(array) {
    var hexStr = "";
    for(var i = 0; i < array.length; i++) {
        var num = array[i];
        if (num < 0) {
            num = array[i] + 0x100000000;
        }
        var str = num.toString(16).toUpperCase();
        var fullStr = str;
        if (str.length < 8) {
            for(var j = 0; j < 8 - str.length; j++) {
                fullStr = "0" + fullStr;
            }
        }
        hexStr = hexStr + fullStr;
    }
    var ret = "";
    for(var i = 0; i < hexStr.length; i += 2) {
        ret = ret + hexStr.substr(i, 2) + " "
    }
    return ret.substr(0, ret.length - 1);
}

// 数组元素个数必须是16的整数倍，不足的在后面补0
function arrayTo16Array(array) {
    var len = array.length;
    var distLen = parseInt((array.length - 1) / 16) * 16 + 16;
    for(var i = array.length; i < distLen; i++) {
        array[i] = 0;
    }
    return array;
}
</script>
</head>
<body>
    <h1>加解密测试</h1>
    AES128，ECB模式，PaddingModeZeros，不足部分补0
    <br>
    <input id="plain" type="text" style="width:500px; height:20px;"/>
        <button type="button" onclick="encryptText()">加密</button>
    <input id="encrypted" type="text" style="width:500px; height:20px;" />
    <br>
    <br>
    <br>
    <input id="todecrypt" type="text" style="width:500px; height:20px;"/>
        <button type="button" onclick="decryptText()">解密</button>
    <input id="decrypted" type="text" style="width:500px; height:20px;" />
</body>
</html>

在浏览器中打开之后效果如下：

输入要加密或解密的字符串，点击加密/解密按钮即可。