在Silverlight中使用RijndaelManaged加密

Question

我正在实现一个webservice客户端，它需要使用128位Rijndael来加密请求。因为Silverlight中不存在RijndaelManaged类，所以我遵循了下面的建议：AesManaged and RijndaelManaged

结果是我得到的结果是正确的(我的意思是，我使用RijndaelManaged得到的是相同的)，只有前32个字符(128位)，完全是块的大小。我不知道我到底做错了什么。我的.Net实现(RijndaelManaged)是这样的：

private static byte[] Encrypt(byte[] PlainTextBytes, byte[] KeyBytes, string InitialVector)
{
    byte[] InitialVectorBytes = Encoding.UTF8.GetBytes(InitialVector);
    RijndaelManaged SymmetricKey = new RijndaelManaged();
    SymmetricKey.Mode = CipherMode.ECB;
    SymmetricKey.Padding = PaddingMode.PKCS7;
    SymmetricKey.BlockSize = 128;
    ICryptoTransform Encryptor = SymmetricKey.CreateEncryptor(KeyBytes, InitialVectorBytes);
    MemoryStream MemStream = new MemoryStream();
    CryptoStream CryptoStream = new CryptoStream(MemStream, Encryptor, CryptoStreamMode.Write);
    CryptoStream.Write(PlainTextBytes, 0, PlainTextBytes.Length);
    CryptoStream.FlushFinalBlock();
    byte[] CipherTextBytes = MemStream.ToArray();
    MemStream.Close();
    CryptoStream.Close();

    return CipherTextBytes;
}

而我的Silverlight是：

private string Encrypt(byte[] PlainTextBytes, byte[] KeyBytes, string InitialVector)
{
    AesManaged SymmetricKey = new AesManaged();
    byte[] InitialVectorBytes = SymmetricKey.IV;
    //NOTE- because Mode and Padding don't exist in AESManaged for Silverlight, I have to do the padding myself
    //for an empty InitalVector (which is my case)
    for (int i = 0; i < InitialVectorBytes.Length; i++) InitialVectorBytes[i] = 0;
    SymmetricKey.BlockSize = 128;
    ICryptoTransform Encryptor = SymmetricKey.CreateEncryptor(KeyBytes, InitialVectorBytes);
    MemoryStream MemStream = new MemoryStream();
    CryptoStream CryptoStream = new CryptoStream(MemStream, Encryptor, CryptoStreamMode.Write);
    CryptoStream.Write(PlainTextBytes, 0, PlainTextBytes.Length);
    CryptoStream.FlushFinalBlock();
    byte[] CipherTextBytes = MemStream.ToArray();
    MemStream.Close();
    CryptoStream.Close();

    return CipherTextBytes;
}

Answer 1

还不清楚是否真的清除了IV，您只是将其作为字节数组获取，然后将其清除，但我不确定IV属性是否在返回之前复制了内部值。我会用这个：

SymmetricKey.BlockSize = 128;
SymmetricKey.IV = new byte[SymmetricKey.BlockSize / 8];

(顺便说一句，我还会停止对参数和局部变量使用PascalCase。通常的约定是对非常数变量使用camelCase。)

编辑:示例代码来演示你的代码并没有真正改变IV：

AesManaged aes = new AesManaged();
byte[] iv = aes.IV;
iv[0] = 1;
iv[1] = 2;
Console.WriteLine(BitConverter.ToString(iv));      
Console.WriteLine(BitConverter.ToString(aes.IV));

示例输出：

01-02-01-1B-6E-05-B8-2A-C0-86-17-EF-A2-80-60-7B
D8-48-01-1B-6E-05-B8-2A-C0-86-17-EF-A2-80-60-7B

换句话说，改变数组中的值实际上并不会改变IV。

Answer 2

您的.NET版本使用EBC模式，而Silverlight版本使用CBC。第一个输出块在两个版本中是相同的，因为在ECB模式下不使用初始化向量，而在CBC模式下初始化向量为零。在CBC模式中，每个块与前一个块进行XORed (第一个块使用初始化向量进行XORed )，然后加密，而在EBC模式中，每个块按原样加密。