javascript - CryptoJS AES CBC 256 解密在明文中间添加额外的字节

Question

我正在编写一个 Chrome 扩展程序，它使用 CryptoJS 进行一些 Apache Thrift 工作。我目前正在尝试让 CryptoJS 工作。我在使用 CryptoJS 解密由 CryptoJS 加密的数据时遇到问题。我在下面附上一个测试用例，在问题描述之后。

发生的事情如下，我有一个“字节”数组:

var bArr = [11,0,1,0,0,0,6,100,105,103,101,115,116,11,0,2,0,0,0,152,67,119,65,66,65,65,65,65,69,109,78,111,99,109,57,116,90,83,49,48,90,88,78,48,76,87,78,115,97,87,86,117,100,65,103,65,65,103,65,65,49,68,69,75,65,65,77,65,65,65,65,65,86,75,102,66,85,103,115,65,66,65,65,65,65,67,81,49,90,68,99,119,77,71,73,120,78,67,48,121,78,84,90,107,76,84,81,119,77,109,81,116,79,84,65,48,90,105,48,52,79,84,86,105,78,68,73,50,89,109,78,108,78,84,99,76,65,65,85,65,65,65,65,85,89,50,104,121,98,50,49,108,76,87,78,115,97,87,86,117,100,67,49,122,90,87,78,121,90,88,81,65,11,0,3,0,0,0,36,52,51,52,55,54,56,98,53,45,50,48,102,102,45,52,99,100,102,45,56,53,97,50,45,57,49,49,56,50,98,55,98,51,102,57,53,0];
var stringToEncode = String.fromCharCode.apply(null, bArr);

我用 CryptoJS 加密然后解密。加密前的前 25 个字节:

11,0,1,0,0,0,6,100,105,103,101,115,116,11,0,2,0,0,0,152,67,119,65,66,65

解密后:

11,0,1,0,0,0,6,100,105,103,101,115,116,11,0,2,0,0,0,194,152,67,119,65,66

唯一的区别是在位置 20 处多了一个 194。显然，除了填充之外，所有其他字节都完全相同。我试图了解这是从哪里来的。

关于帽子的更多信息是这些字节。这是一个包含 3 个字段的 Thrift 结构，字段 2 包含另一个嵌入式 Thrift 结构的 Base64 表示。输入示例的前 20 个字节:

• 11,0,1:字符串类型的 Thrift 字段，fid 1
• 0,0,0,6:fid 1的值的int32长度
• 100,67,119,65,66,65:字符串“摘要”
• 11,0,2:字符串类型的 Thrift 字段，fid 2
• 0,0,0,152:fid 2的值的int32长度
• 67 ...直到下一个字节 11:嵌入式结构的 Base64 表示

由于解密问题，Thrift 解析器错误地识别了 fid 2 值的长度。

我相信我在带有 PKCS7 填充的 OpenSSL 模式下使用带有 32 字节 key (SHA256) 和 16 字节 IV 的 AES256 CBC。

这是我的 qunit 测试。

test("Decryption", function() {
  var bArr = [11,0,1,0,0,0,6,100,105,103,101,115,116,11,0,2,0,0,0,152,67,119,65,66,65,65,65,65,69,109,78,111,99,109,57,116,90,83,49,48,90,88,78,48,76,87,78,115,97,87,86,117,100,65,103,65,65,103,65,65,49,68,69,75,65,65,77,65,65,65,65,65,86,75,102,66,85,103,115,65,66,65,65,65,65,67,81,49,90,68,99,119,77,71,73,120,78,67,48,121,78,84,90,107,76,84,81,119,77,109,81,116,79,84,65,48,90,105,48,52,79,84,86,105,78,68,73,50,89,109,78,108,78,84,99,76,65,65,85,65,65,65,65,85,89,50,104,121,98,50,49,108,76,87,78,115,97,87,86,117,100,67,49,122,90,87,78,121,90,88,81,65,11,0,3,0,0,0,36,52,51,52,55,54,56,98,53,45,50,48,102,102,45,52,99,100,102,45,56,53,97,50,45,57,49,49,56,50,98,55,98,51,102,57,53,0];
  var stringToEncode = String.fromCharCode.apply(null, bArr);
  var symmetricKey = "v3JElaRswYgxOt4b";

  var key = CryptoJS.enc.Latin1.parse( CryptoJS.enc.Latin1.stringify( CryptoJS.SHA256( symmetricKey ) ) );
  var iv  = CryptoJS.lib.WordArray.random( 16 );

  var encrypted = CryptoJS.AES.encrypt( stringToEncode,
                                        key,
                                        { iv: iv, format: CryptoJS.format.OpenSSL }
                                      ).ciphertext.toString(CryptoJS.enc.Latin1);

  var decrypted = CryptoJS.AES.decrypt( { ciphertext: CryptoJS.enc.Latin1.parse(encrypted) },
                                          key,
                                          { iv: iv, padding: CryptoJS.pad.NoPadding }
                                      ).toString(CryptoJS.enc.Latin1);

  var buf = [];
  for (var i=0; i<decrypted.length; i++) {
    buf.push( decrypted.charCodeAt(i) );
  }

  var bstr1 = "";
  for (var i=0; i<bArr.length; i++) {
    bstr1 += (i>0) ? ","+bArr[i] : bArr[i]+"";
  }
  var bstr2 = "";
  for (var i=0; i<buf.length; i++) {
    bstr2 += (i>0) ? ","+buf[i] : buf[i]+"";
  }

  console.log("------------------------------------------");
  console.log(bstr1);
  console.log(bstr2);
  console.log("------------------------------------------");

  equal( stringToEncode.slice(0,200), decrypted.slice(0,200) );
});

我的测试 HTML 包装器加载了这些:

<script src="../bower_components/jquery/dist/jquery.min.js"></script>
<script src="../bower_components/js-base64/base64.js"></script>
<script src="../bower_components/thrift/lib/js/src/thrift.js"></script>
<script src="../bower_components/underscore/underscore-min.js"></script>
<script src="../bower_components/qunit/qunit/qunit.js"></script>
<script src="../bower_components/browserify-cryptojs/components/core.js"></script>
<script src="../bower_components/browserify-cryptojs/components/sha256.js"></script>
<script src="../bower_components/browserify-cryptojs/components/enc-base64.js"></script>
<script src="../bower_components/browserify-cryptojs/components/cipher-core.js"></script>
<script src="../bower_components/browserify-cryptojs/components/format-hex.js"></script>
<script src="../bower_components/browserify-cryptojs/components/aes.js"></script>
<script src="../bower_components/browserify-cryptojs/components/pad-nopadding.js"></script>
<!-- the Test Suite-->
<script type="text/javascript" src="test-client.js" charset="utf-8"></script>
<!-- CSS-->
<link rel="stylesheet" href="../bower_components/qunit/qunit/qunit.css" type="text/css" media="screen" />

我的 bower.json 是:

{
  "name": "gossiperl-client-chrome",
  "version": "0.1.0",
  "main": "manifest.json",
  "dependencies": {
    "jquery": "~1.11.0",
    "underscore": "~1.7.0",
    "thrift": "radekg/thrift#js-binary-protocol",
    "js-base64": "~2.1.5",
    "qunit": "~1.14.0",
    "browserify-cryptojs": "~0.3.1"
  },
  "authors": [
    "radekg <...@....com>"
  ],
  "description": "Gossiperl Chrome client with a sample application",
  "keywords": [
    "gossiperl",
    "client"
  ],
  "license": "MIT",
  "homepage": "http://....com",
  "private": true
}

Answer 1

问题是 CryptoJS 将输入视为 UTF-8 输入字符串，除非它已经是 WordArray。如果您的输入不是 UTF-8，这当然是个问题。您看到的是 0x80 (128) 以上的值被转换为两个字节以修复 UTF-8 编码。

只要 WordArray 不支持从数组到 WordArray 的直接转换，您就可以直接转换为十六进制，然后再转换为 WordArray。缺少此功能有点奇怪。

以下将具有无符号字节值的数组转换为十六进制(对无效字节值有一点警惕):

function tohex(unsignedByteArray) {
    var hex = "";
    for (var i = 0; i < unsignedByteArray.length; i++) {
        var c = unsignedByteArray[i];
        if (c < 0 || c > 255) {
            throw "Value not an unsigned byte in array";
        }
        var h = c.toString(16);
        if (h.length == 1) {
            hex += "0" + h;
        } else {
            hex += h;
        }
    }
    return hex;
}

function fromhex(hex) {
    if (hex.length % 2 !== 0) {
        throw "Hex string should contain even number of hex digits, one per byte";
    }
    var unsignedByteArray = [];
    for (var i = 0; i < hex.length; i = i + 2) {
        var h = hex.substring(i, i + 2);
        if (!/^[0-9a-f]{2}$/i.test(h)) {
            throw "Invalid hexdigit at offset " + i;
        }
        var c = parseInt(h, 16);
        unsignedByteArray[unsignedByteArray.length] = c;
    }
    return unsignedByteArray;
}

所以你可以像这样使用这些函数:

var bArr = [11, 0, 1, 0, 0, 0, 6, 100, 105, 103, 101, 115, 116, 11, 0, 2, 0, 0, 0, 152, 67, 119, 65, 66, 65, 65, 65, 65, 69, 109, 78, 111, 99, 109, 57, 116, 90, 83, 49, 48, 90, 88, 78, 48, 76, 87, 78, 115, 97, 87, 86, 117, 100, 65, 103, 65, 65, 103, 65, 65, 49, 68, 69, 75, 65, 65, 77, 65, 65, 65, 65, 65, 86, 75, 102, 66, 85, 103, 115, 65, 66, 65, 65, 65, 65, 67, 81, 49, 90, 68, 99, 119, 77, 71, 73, 120, 78, 67, 48, 121, 78, 84, 90, 107, 76, 84, 81, 119, 77, 109, 81, 116, 79, 84, 65, 48, 90, 105, 48, 52, 79, 84, 86, 105, 78, 68, 73, 50, 89, 109, 78, 108, 78, 84, 99, 76, 65, 65, 85, 65, 65, 65, 65, 85, 89, 50, 104, 121, 98, 50, 49, 108, 76, 87, 78, 115, 97, 87, 86, 117, 100, 67, 49, 122, 90, 87, 78, 121, 90, 88, 81, 65, 11, 0, 3, 0, 0, 0, 36, 52, 51, 52, 55, 54, 56, 98, 53, 45, 50, 48, 102, 102, 45, 52, 99, 100, 102, 45, 56, 53, 97, 50, 45, 57, 49, 49, 56, 50, 98, 55, 98, 51, 102, 57, 53, 0];
var bArrHex = tohex(bArr);

var stringToEncode = CryptoJS.enc.Hex.parse(bArrHex);

var symmetricKey = "v3JElaRswYgxOt4b";

var key = CryptoJS.enc.Latin1.parse(CryptoJS.enc.Latin1.stringify(CryptoJS.SHA256(symmetricKey)));

var iv = CryptoJS.lib.WordArray.random(16);

var encrypted = CryptoJS.AES.encrypt(stringToEncode, key, { iv: iv, format: CryptoJS.format.OpenSSL });

var decrypted = CryptoJS.AES.decrypt(encrypted, key, { iv: iv, format: CryptoJS.format.OpenSSL });

var result = fromhex(decrypted.toString(CryptoJS.enc.Hex));

console.log(result);

if (bArr.toString() == result.toString()) {
    console.log("success");
}

请注意，encrypted 在用作字符串时会自动编码为 base64。您不能对密文使用 Latin1 编码。请注意，您的 key 还应包含随机字节，而不仅仅是现在的可打印字符。

最后请注意，在没有 MAC 的情况下发送 AES 加密文本本质上是不安全的，例如因为填充 oracle 攻击以及任何人都可以更改传输中的数据这一事实。