What is the C# equivalent of Java BouncyCastle AES decryption?

Question

I have the following Java code that needs to be translated to c#:

public static byte[] encryptAES(byte[] toEncrypt, byte[] key,
                                boolean encrypte) throws Exception {

    Security.addProvider(new BouncyCastleProvider());

    byte[] iv = { (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
                  (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
                  (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
                  (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00 };

    IvParameterSpec salt = new IvParameterSpec(iv);
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding", "BC");

    if (encrypte == false)
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"),  salt);
    else
        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "AES"),  salt);

    byte[] result = cipher.doFinal(toEncrypt);
    return result;
}

How do you do the equivalent of:

Security.addProvider(new BouncyCastleProvider());

and what is the equivalent of:

IvParameterSpec salt = new IvParameterSpec(iv);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding", "BC");

Answer 1

Try this out.

According to http://social.msdn.microsoft.com/Forums/en-US/13a20d89-7d84-4f7d-8f5c-5ae108a7f5cf/des-encryption-padding-mode-pkcs5?forum=csharplanguage pkcs#5 is the same as pkcs#7.

public static byte[] EncryptDataAES(byte[] toEncrypt, byte[] key)
    {
        byte[] encryptedData;
        byte[] iv = { (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
                                                        (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
                                                        (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00,
                                                        (byte) 0x00, (byte) 0x00, (byte) 0x00, (byte) 0x00 };


        using (SymmetricAlgorithm aes = SymmetricAlgorithm.Create())
        {
            aes.Mode = CipherMode.CBC;
            aes.Key = key;
            aes.IV = iv;
            aes.Padding = PaddingMode.PKCS7;
            ICryptoTransform encryptor = aes.CreateEncryptor();
            using (MemoryStream mStream = new MemoryStream())
            {
                using (CryptoStream cStream = new CryptoStream(mStream, encryptor, CryptoStreamMode.Write))
                {
                    cStream.Write(toEncrypt, 0, toEncrypt.Length);
                    cStream.FlushFinalBlock();
                    encryptedData = mStream.ToArray();
                }
            }
        }
        return encryptedData;
    }

To Decrypt:

public static string DecryptDataAES(byte[] cipherText, byte[] key, byte[] iv)
        {
            string plaintext = null;

            using (Rijndael rijAlg = Rijndael.Create())
            {
                rijAlg.Key = key;
                rijAlg.IV = iv;

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

                // Create the streams used for decryption. 
                using (MemoryStream msDecrypt = new MemoryStream(cipherText))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }

            }

            return plaintext;
        }

Use this to decode your key that is a hex representation of the bytes.

public static byte[] StringToByteArray(String hex)
    {
        int NumberChars = hex.Length / 2;
        byte[] bytes = new byte[NumberChars];
        using (var sr = new StringReader(hex))
        {
            for (int i = 0; i < NumberChars; i++)
                bytes[i] =
                  Convert.ToByte(new string(new char[2] { (char)sr.Read(), (char)sr.Read() }), 16);
        }
        return bytes;
    }