如何解密一个ArrayBuffer? [英] How to decrypt an ArrayBuffer?

问题描述

我一直在尝试使用 CryptoJS 解密一个 ArrayBuffer 对象，但到目前为止它总是返回一个空白的 WordArray.文件(图像)在 iOS 和 Android 应用程序中加密，发送到服务器，并在此网络应用程序中下载以进行解密和显示.iOS 和 Android 应用程序能够毫无问题地解密文件，因此加密过程没有任何问题.

I've been trying to decrypt an ArrayBuffer object using CryptoJS, but so far it always returns a blank WordArray. The files (images) are encrypted in an iOS and Android app, sent to a server, and downloaded in this web app to be decrypted and displayed. The iOS and Android apps are able to decrypt the files without problems, so there's nothing wrong with the encryption process.

文件使用 XMLHttpRequest 下载，responseType 设置为 arraybuffer.到目前为止，这是我的代码:

The files are downloaded with an XMLHttpRequest with responseType set to arraybuffer. Here's my code so far:

// Decrypt a Base64 encrypted string (this works perfectly)
String.prototype.aesDecrypt = function(key) {

    var nkey = CryptoJS.enc.Hex.parse(key.sha256());
    return CryptoJS.AES.decrypt(this.toString(), nkey, {
        iv: CryptoJS.enc.Hex.parse('00000000000000000000000000000000'),
        mode: CryptoJS.mode.CBC,
        padding: CryptoJS.pad.Pkcs7
    }).toString(CryptoJS.enc.Utf8);

}

// Decrypt a plain encrypted ArrayBuffer (this is the problem, it always outputs an empty WordArray)
ArrayBuffer.prototype.aesDecrypt = function(key) {

    // Get key
    if (!key) return null;
    var nkey = CryptoJS.enc.Hex.parse(key.sha256());

    // Get input (if I pass the ArrayBuffer directly to the create function, it returns
    // a WordList with sigBytes set to NaN)
    //var input = CryptoJS.lib.WordArray.create(this);
    var input = CryptoJS.lib.WordArray.create(new Uint8Array(this));

    // Decrypt
    var output = CryptoJS.AES.decrypt(input, nkey, {
        iv: CryptoJS.enc.Hex.parse('00000000000000000000000000000000'),
        mode: CryptoJS.mode.CBC,
        padding: CryptoJS.pad.Pkcs7
    });

    // Output is an empty WordList
    console.log("Output: ", output);

}

我的另一个问题是如何将 WordArray 转换为 ArrayBuffer?

Another question I have is how do you convert a WordArray to an ArrayBuffer?

推荐答案

ArrayBuffer 的转换 ->WordArray 已在 CryptoJS 的 问题 46.为此，添加了一个 TypedWordArray，您还可以在其中传递 ArrayBuffer.

The conversion of ArrayBuffer -> WordArray has been discussed in CryptoJS's issue 46. For that reason a TypedWordArraywhere you can also pass an ArrayBuffer has been added.

要使用它，请另外包含以下脚本:

To use that additionally include the following script:

<script src="http://crypto-js.googlecode.com/svn/tags/3.1/build/components/lib-typedarrays.js"></script>

然后你可以简单地做:

var wordArray = CryptoJS.lib.WordArray.create(arrayBuffer);

/* perform decryption of `wordArray` */

<小时>

要将生成的 decryptedWordArray 重新转换为 ArrayBuffer，最简单的方法可能是首先将其转换为 Base64-String (如此处所述)，然后将该字符串解码为所需的ArrayBuffer(请参阅此处).整个过程看起来像这样:

---

To reconvert the resulting decryptedWordArray to an ArrayBuffer, the simplest approach would probably be, to first convert it to a Base64-String (as discussed here) and then decode that String to the desired ArrayBuffer (see here). The whole procedure would look something like this:

dcWordArray = ... // your decrypted WordArray
dcBase64String = dcWordArray.toString(CryptoJS.enc.Base64); // to Base64-String
dcArrayBuffer = base64DecToArr(dcBase64String).buffer; // to ArrayBuffer

为了更有效的转换(不需要中间的 Base64String)，请查看 Aletheios 对 那个 问题(函数 wordToByteArray(wordArray) 然后做 .buffer).

For a more efficient conversion (no intermediate Base64String necessary) check out Aletheios answer to that question (the function wordToByteArray(wordArray) and then do .buffer).

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