C# 发送 byte[] 到服务器，解密内容并将其作为 byte[] 发送回客户端

Question

我的问题如下：

我有一个 client/server 应用程序通过套接字连接。我客户的任务是按字节向服务器发送文件。服务器获取字节，解密它们，将其发送回客户端，然后他将它们写入磁盘上的新文件中。

我每次都会在这行代码处遇到服务器端异常（System.Security.Cryptography.Exception：填充无效且无法删除）：plaintext = sr.ReadToEnd();

有人可以帮我解决我的问题吗？

这里是解密代码：

public byte[] Dec(byte[] content, byte[] Key, byte[] IV, int fileLength, string filepath, int chunkSize, int bytesToRead)
    {
        byte[] contentDec;
        string plaintext = null;
        System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("IV");

        using (RijndaelManaged rijAlg = new RijndaelManaged())
        {
            rijAlg.Key = Key;
            rijAlg.IV = IV;

            ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);


            using (MemoryStream ms = new MemoryStream(content))
            {
                using (CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader sr = new StreamReader(cs))
                    {
                        plaintext = sr.ReadToEnd();
                        cs.FlushFinalBlock();
                    }
                    contentDec = encoding.GetBytes(plaintext);
                }
            }
        }
        return contentDec;
    }

这是我的加密代码：

    public byte[] Enc(byte[] content,byte[] Key, byte[] IV, int fileLength,string filepath, int chunkSize, int bytesToRead)
    {
        byte[] contentEnc;
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("IV");
        using (RijndaelManaged rijAlg = new RijndaelManaged())
        {
            rijAlg.Key = Key;
            rijAlg.IV = IV;
            ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);
            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter sw = new StreamWriter(cs))
                    {
                        sw.Write(content);
                    }
                    contentEnc = ms.ToArray();
                }
            }
        }
        return contentEnc;
    }

在客户端我调用这样的加密方法

        int chunkSize = 1024;
        byte[] chunk = new byte[chunkSize];
        using (FileStream fileReader = new FileStream(plainPath, FileMode.Open, FileAccess.Read))
        using (FileStream filewriter = new FileStream(pathEncrypt, FileMode.Create, FileAccess.ReadWrite))
        using (BinaryReader binaryReader = new BinaryReader(fileReader))
        using (RijndaelManaged myRijndael = new RijndaelManaged())
        {
            myRijndael.GenerateKey();
            myRijndael.GenerateIV();
            Key = myRijndael.Key;
            IV = myRijndael.IV;
            int bytesToRead = (int)fileReader.Length;
            do
            {
                chunk = service.Enc(binaryReader.ReadBytes(chunkSize), Key, IV,(int)fileReader.Length, 
                    fileReader.Name, chunkSize, bytesToRead);
                filewriter.Write(chunk, 0, chunk.Length);
                bytesToRead -= chunkSize;
            } while (bytesToRead > 0);
        }

Key 和 IV 声明为私有字节[]

在客户端我调用这样的解密方法

        int chunkSize = 1024;
        byte[] chunk = new byte[chunkSize];
        using (FileStream fileReader = new FileStream(pathEncrypt, FileMode.Open, FileAccess.Read))
        using (FileStream filewriter = new FileStream(pathDecrypt, FileMode.Create, FileAccess.ReadWrite))
        using (BinaryReader binaryReader = new BinaryReader(fileReader))
        {
            int bytesToRead = (int)fileReader.Length;

            do
            {
                chunk = service.Dec(binaryReader.ReadBytes(chunkSize), Key, IV, (int)fileReader.Length, 
                    fileReader.Name, chunkSize, bytesToRead);
                filewriter.Write(chunk, 0, chunk.Length);
                bytesToRead -= chunkSize;
            } while (bytesToRead > 0);
        }

编辑：这是我在客户端和服务器之间建立的连接。

服务器： var host = new ServiceHost(类型(服务), 新 Uri("net.pipe://localhost"));

        host.AddServiceEndpoint(typeof(TiService),
                                new NetNamedPipeBinding(), "TestService");
        host.Open();
        Console.WriteLine("Server connection established...");
        Console.ReadKey();

客户：

var callback = new Callback();
var context = new InstanceContext(callback);
var pipeFactory =
new DuplexChannelFactory<TiService>(context,
new NetNamedPipeBinding(),
new EndpointAddress("net.pipe://localhost/TestService"));

service = pipeFactory.CreateChannel();
service.Connect();

Answer 1

您的问题始于在加密中使用 StreamWriter。它用于编写文本文件，而不是任意文件。当您调用 sw.Write(content) 时，它只是调用 content.ToString()，即 return "System.Byte[]"，而不是您可能期望的数组的每个字节。要修复它，只需编写 CryptoStream，无需使用 StreamWriter，如下所示：

using (var rijAlg = new AesCng())
{
    rijAlg.Key = Key;
    rijAlg.IV = IV;
    ICryptoTransform encryptor = rijAlg.CreateEncryptor();
    using (MemoryStream ms = new MemoryStream())
    {
        using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
        {
            cs.Write(content, 0, content.Length);               
        }
        contentEnc = ms.ToArray();
    }
}

您可能注意到我使用的是 AesCng 而不是 RijndaelManaged。为什么？因为它在我的测试中要快得多，除非你真的需要非标准块，否则使用 RijndaelManaged 没有任何好处。另外，我使用无参数的 CreateEncryptor，因为您已经在前面的行中设置了密钥和 IV。

解密同理。您不应该将它们视为文本，因此：

var buffer = new byte[content.Length]; //at first its size is actual size+padding

using (var rijAlg = new AesCng())
{
    rijAlg.Key = Key;
    rijAlg.IV = IV;

    ICryptoTransform decryptor = rijAlg.CreateDecryptor();

    using (MemoryStream ms = new MemoryStream(content))
    {
        using (CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Read))
        {
            var actualSize = cs.Read(buffer, 0, content.Length);
            //we write the decrypted content to the buffer, and get the actual size

            Array.Resize(ref buffer, actualSize);
            //then we resize the buffer to the actual size
        }
    }
}
return buffer;

此外，您对 Enc 和 Dec 的使用过于复杂。它已经能够自己处理整个文件。所以要加密文件，只需使用

var original = File.ReadAllBytes("originalPath");
var enc = Enc(original, rM.Key, rM.IV);
File.WriteAllBytes("encryptedPath", enc);

要解密文件，只需使用

var enc = File.ReadAllBytes("encryptedPath");
var dec = Dec(enc, rM.Key, rM.IV);
File.WriteAllBytes("decryptedPath", dec);

如您所见，我在 Enc 和 Dec 上丢弃了 fileLength、filepath、chunkSize 和 bytesToRead，因为您当前的代码实际上并没有使用它们。我已经在 ASCII、Unicode 和 UTF-8 上尝试了带有短文本文件的代码，以及带有大型二进制文件的代码，所有这些都在最终解密的文件上使用相同的哈希值成功加密和解密。

编辑：

将代码变成直接的文件流写入，实际上让一切变得如此简单。

public static void Transform(string source, string target, ICryptoTransform transf)
{
    var bufferSize = 65536;
    var buffer = new byte[bufferSize];


    using (var sourceStream = new FileStream(source, FileMode.Open))
    {
        using (var targetStream = new FileStream(target, FileMode.OpenOrCreate))
        {
            using (CryptoStream cs = new CryptoStream(targetStream, transf, CryptoStreamMode.Write))
            {
                var bytesRead = 0;
                do
                {
                    bytesRead = sourceStream.Read(buffer, 0, bufferSize);
                    cs.Write(buffer, 0, bytesRead);
                } while (bytesRead != 0);
            }
        }

    }


}

public static void Enc(string source, byte[] Key, byte[] IV, string target)
{
    using (var rijAlg = new AesCng())
    {
        rijAlg.Key = Key;
        rijAlg.IV = IV;
        ICryptoTransform encryptor = rijAlg.CreateEncryptor();
        Transform(source, target, encryptor);
    }

}
public static void Dec(string source, byte[] Key, byte[] IV, string target)
{
    using (var rijAlg = new AesCng())
    {
        rijAlg.Key = Key;
        rijAlg.IV = IV;
        ICryptoTransform decryptor = rijAlg.CreateDecryptor();
        Transform(source, target, decryptor);
    }

}

用法是：

Enc(@"originalPath", key, iv, @"encryptedPath");
Dec(@"encrypedPath", key, iv, @"decryptedPath");

C# 发送 byte[] 到服务器，解密内容并将其作为 byte[] 发送回客户端

C# Send byte[] to server, decrypt content and send it as byte[] back to client

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