CryptoJS AES CBC 256解密在明文中间添加了额外的字节

Question

CryptoJS AES CBC 256解密在明文中间添加了额外的字节

3

我正在编写一个Chrome扩展程序，其中使用CryptoJS进行一些Apache Thrift工作。我目前正在尝试让CryptoJS正常工作。我遇到了一个问题，即CryptoJS无法解密由CryptoJS加密的数据。在问题描述之后，我附上了一个测试用例。

发生的情况如下，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);

我使用CryptoJS对其进行加密，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

唯一的区别是在第20个位置上有一个额外的194。除了填充之外，所有其他字节都完全相同。我正在尝试理解这是从哪里来的。

有关这些字节的更多信息。这是一个包含3个字段的Thrift结构，第二个字段包含另一个嵌入式Thrift结构的Base64表示。输入的前20个字节如下：

- 11,0,1：类型为字符串、fid为1的Thrift字段 - 0,0,0,6：fid 1值的int32长度 - 100,67,119,65,66,65：字符串“digest” - 11,0,2：类型为字符串、fid为2的Thrift字段 - 0,0,0,152：fid 2值的int32长度 - 67 ... 直到下一个字节11：嵌入结构的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。

我相信我正在使用带有32字节密钥（SHA256）和16字节IV的AES256 CBC，在PKCS7填充的OpenSSL模式下。

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) );
});

我测试用的HTML封装加载了以下内容：

<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文件如下：

{
  "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
}

- user56250

C2或194是UTF-8中双字节编码字符的一部分。欢迎来到JavaScript字符串/二进制地狱。哦，152是第一个不属于US-ASCII的字符 - 需要用UTF-8编码两个字节。 - Maarten Bodewes

啊，这个没有办法绕过去吗？ - user56250

我正在寻找它，但是CryptoJS没有直接的数组转换为WordArray。答案可能是先转换为十六进制，然后创建一个WordArray（这相当低效，但JavaScript通常用于字节数组/加密操作）。 - Maarten Bodewes

有点遗憾。Erlang、Java、Mono、Ruby中的所有其他软件都期望以此格式提供数据 - 不需要编码外部摘要。也许像你说的那样，直接从我的数组创建一个wordarray可能是一个选择。或者看看NaCl :-/ - user56250

别急，只是一点编码/解码问题不应该阻止你 :P - Maarten Bodewes

2个回答

1

作为额外的参考。被接受的答案包含了解决问题的关键。

问题在于，除非输入已经是WordArray，否则CryptoJS会将其视为UTF-8输入字符串。

事实上，我已将我的测试更改为以下内容:

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 dataToEncrypt = toCryptoJSWordArray( 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( dataToEncrypt,
                                        key,
                                        { iv: iv, format: CryptoJS.format.OpenSSL }
                                      ).ciphertext.toString(CryptoJS.enc.Latin1);

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

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

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

  deepEqual( bArr.slice(0,200), decrypted.slice(0,200) );
});

function toCryptoJSWordArray(bArr) {
  var latin1StrLength = bArr.length;
  // Convert
  var words = [];
  for (var i = 0; i < bArr.length; i++) {
    words[i >>> 2] |= (bArr[i] & 0xff) << (24 - (i % 4) * 8);
  }
  return new CryptoJS.lib.WordArray.init(words, bArr.length);
}

function toByteArray(str) {
  var bArr = [];
  for (var i=0; i<str.length; i++) {
    bArr.push( str.charCodeAt(i) );
  }
  return bArr;
}

这将从我的字节数组创建一个WordArray，然后进行加密和解密。解密后的数据返回正确。

- user56250

啊，有趣的添加，少转换=更好。 - Maarten Bodewes

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Maarten Bodewes · Accepted Answer

问题是CryptoJS会将输入视为UTF-8输入字符串，除非它已经是WordArray。如果您的输入不是UTF-8，则会出现问题。您看到的是值大于0x80（128）被转换为两个字节以修复UTF-8编码的问题。

只要WordArray不支持从数组直接转换为WordArray，您就可以使用直接转换为十六进制然后转换为WordArray的方法。这个功能缺失有点奇怪。

以下是将带有无符号字节值的数组转换为十六进制数（与无效字节值有关的保护措施）：

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;
}

所以您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，当作为字符串使用时，encrypted会自动编码为base64格式。您不能使用Latin1编码来加密文本。请注意，您的密钥也应该包含随机字节，而不仅仅是可打印字符。

最后请注意，发送没有MAC的AES加密文本本质上是不安全的，例如由于填充预言攻击和任何人都可以更改传输数据的事实。