System.Security.Cryptography.CryptoStream.WriteByte C# (CSharp) Method

        public override void WriteByte(byte value)
        {
            // If there's room in the input buffer such that even with this byte we wouldn't
            // complete a block, simply add the byte to the input buffer.
            if (_inputBufferIndex + 1 < _inputBlockSize)
            {
                _inputBuffer[_inputBufferIndex++] = value;
                return;
            }

            // Otherwise, the logic is complicated, so we simply fall back to the base 
            // implementation that'll use Write.
            base.WriteByte(value);
        }

        public static void DecryptFile(string strKey, string pathCypheredTextFile, string pathPlainTextFile)
        {
            // Place la clé de déchiffrement dans un tableau d'octets
            byte[] key = GenerateAlgotihmInputs(strKey);

            // Place le vecteur d'initialisation dans un tableau d'octets
            byte[] iv = GenerateAlgotihmInputs(strKey);

            // Filestream of the new file that will be decrypted.
            Directory.CreateDirectory(Directory.GetParent(pathPlainTextFile).FullName);
            FileStream fsCrypt = new FileStream(pathPlainTextFile, FileMode.Create);

            RijndaelManaged rijndael = new RijndaelManaged();
            rijndael.Mode = CipherMode.CBC;
            rijndael.Key = key;
            rijndael.IV = iv;

            ICryptoTransform aesDecryptor = rijndael.CreateDecryptor();

            CryptoStream cs = new CryptoStream(fsCrypt, aesDecryptor, CryptoStreamMode.Write);

            // FileStream of the file that is currently encrypted.
            FileStream fsIn = new FileStream(pathCypheredTextFile, FileMode.OpenOrCreate);

            int data;

            while ((data = fsIn.ReadByte()) != -1)
                cs.WriteByte((byte)data);
            cs.Close();
            fsIn.Close();
            fsCrypt.Close();
        }