Question

I use this function to decrypt a executable file :

public static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV) ... 

But, this function return a string output I can see the ASCII output of my corresponding decrypted file. But, I need to get a byte[] output.

I have try many thing but I’m stuck: I need a DecryptBytesToBytes function

Answer 1

As a variant:

    static byte[] DecryptBytesToBytes (byte[] cipherText, byte[] Key, byte[] IV)
    {
        // Check arguments. 
        if (cipherText == null || cipherText.Length <= 0)
            throw new ArgumentNullException("cipherText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("Key");

        // Declare the string used to hold 
        // the decrypted text.
        byte[] encrypted = null;

        // Create an AesCryptoServiceProvider object 
        // with the specified key and IV. 
        using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())
        {
            aesAlg.Key = Key;
            aesAlg.IV = IV;

            // Create a decrytor to perform the stream transform.
            ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.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))
                    {
                        string encrypted_text = srDecrypt.ReadToEnd();
                        encrypted = new byte[encrypted_text.Length * sizeof(char)];
                        System.Buffer.BlockCopy(encrypted_text.ToCharArray(), 0, encrypted, 0, encrypted.Length);
                    }
                }
            }

        }

        return encrypted;
    }