AES single block decryption/encryption _

AES_Decrypt_block.cs

private static byte[] AES_Decrypt_block(byte[] cipherText, byte[] Key)
{
    // Declare the string used to hold the decrypted text. 
    byte[] output_buffer = new byte[cipherText.Length];

    using (AesManaged aesAlg = new AesManaged())
    {
        //If CBC, must initialize IV = O_{128}
        //aesAlg.Mode = CipherMode.CBC;
        //aesAlg.IV = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
        aesAlg.Mode = CipherMode.ECB;

        aesAlg.BlockSize = 128;
        aesAlg.KeySize = 128;
        aesAlg.Padding = PaddingMode.None;
        aesAlg.Key = Key;
            
        // Create a decrytor to perform the stream transform.
        ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
        decryptor.TransformBlock(cipherText, 0, cipherText.Length, output_buffer, 0);
    }

    return output_buffer;
}

AES_encrypt_block.cs

private static byte[] AES_encrypt_block(byte[] plainText, byte[] Key)
{
    byte[] output_buffer = new byte[plainText.Length];

    using (AesManaged aesAlg = new AesManaged())
    {
        //If CBC, must initialize IV = O_{128}
        //aesAlg.Mode = CipherMode.CBC;
        //aesAlg.IV = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
        aesAlg.Mode = CipherMode.ECB;

        aesAlg.BlockSize = 128;
        aesAlg.KeySize = 128;
        aesAlg.Padding = PaddingMode.None;
        aesAlg.Key = Key;

        // Create a decrytor to perform the stream transform.
        ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
        encryptor.TransformBlock(plainText, 0, plainText.Length, output_buffer, 0);
    }

    return output_buffer;
}