Encryption in c lang. and decryption in c#

问题

I have used Rijndael (Encryption Algorithm) in my server side code, which is in C language. But my client is written in C# and C# provide its own Rijndael class to encrypt and decrypt.

At client side I am using the same password for key generation but the client application is unable to decrypt it. I want to encrypt a file in C and decrypt that file in .NET (C#).

Server Code : http://www.efgh.com/software/rijndael.txt

Client Code :

    public static void Encrypt()
    {

        string password = @"4c696e6775614e6578742431302a4c6f63616c697a6174696f6e2a3949505f3030372a"; // Your Key Here
            /*UnicodeEncoding UE = new UnicodeEncoding();
            byte[] key = UE.GetBytes(password);*/
            Rfc2898DeriveBytes  pdb = new Rfc2898DeriveBytes (password, new byte[] { 0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c });

            string cryptFile = @"F:\Encoding and Decoding\ReadMe_Encrypted.txt";
            FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);

            RijndaelManaged RMCrypto = new RijndaelManaged();
            RMCrypto.KeySize = 256;
            RMCrypto.BlockSize = 256;               
            byte[] key = pdb.GetBytes(RMCrypto.KeySize / 8);
            byte[] iv = pdb.GetBytes(RMCrypto.BlockSize / 8);  
            CryptoStream cs = new CryptoStream(fsCrypt,
                RMCrypto.CreateEncryptor(key, iv),
                CryptoStreamMode.Write);

            FileStream fsIn = new FileStream(@"F:\Encoding and Decoding\ReadMe.txt", FileMode.Open);

            int data;
            while ((data = fsIn.ReadByte()) != -1)
                cs.WriteByte((byte)data);

            fsIn.Close();
            cs.Close();
            fsCrypt.Close();

    }
    public static void Decrypt()
    {
        string password = @"4c696e6775614e6578742431302a4c6f63616c697a6174696f6e2a3949505f3030372a"; // Your Key Here

       /* UnicodeEncoding UE = new UnicodeEncoding();
        byte[] key = UE.GetBytes(password);*/
       // PasswordDeriveBytes pdb = new PasswordDeriveBytes(password, new byte[] { 0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c });
        Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(password, new byte[] { 0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c });

        FileStream fsCrypt = new FileStream(@"F:\Encoding and Decoding\ReadMe_Encrypted.txt", FileMode.Open);

        RijndaelManaged RMCrypto = new RijndaelManaged();
        RMCrypto.KeySize = 256;
        RMCrypto.BlockSize = 256;
        byte[] key = pdb.GetBytes(RMCrypto.KeySize / 8);
        byte[] iv = pdb.GetBytes(RMCrypto.BlockSize /8);  
        CryptoStream cs = new CryptoStream(fsCrypt, RMCrypto.CreateDecryptor(key, iv), CryptoStreamMode.Read);
     //   CryptoStream cs = new CryptoStream(fsCrypt, RMCrypto.CreateDecryptor(), CryptoStreamMode.Read);


        FileStream fsOut = new FileStream(@"F:\Encoding and Decoding\ReadMe_Decrypted.txt", FileMode.Create);

        int data;
        while ((data = cs.ReadByte()) != -1)
            fsOut.WriteByte((byte)data);

        fsOut.Close();
        cs.Close();
        fsCrypt.Close();
    }

回答1:

In your C# code you're using Rfc2898DeriveBytes to convert your password string into a 256-bit key (under the hood this is actually hashing the password using SHA-1), whereas in the C code you're using the key directly. You probably want to modify the C# code to use the key directly (it looks like a 256-bit key to me, not an ASCII password).

The following should be sufficient:

byte[] key = {0x4c, 0x69, 0x6e, 0x67, ...};

You'll also want to modify the C program to use the correct binary key, rather than taking one on the command line. You can use something like the following:

unsigned char key[KEYLENGTH(KEYBITS)] = {0x4c, 0x69, 0x6e, 0x67, ...};

I'm also not sure if you're using the same mode (http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation). I think the C# code may be using CBC whereas the C code is using ECB. I suggest this as there's an iv in the C# code (generated from the password), but there isn't one in the C code.

You could also try to find a library that you can use from both C and C# and use that instead, for example openssl.

来源：https://stackoverflow.com/questions/11858456/encryption-in-c-lang-and-decryption-in-c-sharp

标签

encryption-symmetric