How to encrypt a folder with large files using AES algorithm in C#

See more:

C#

encryption

Windows-service

AES

Hi Code project mates,

I have a serious problem with encryption and decryption. What I have is a folder which can be in varied sizes but can have an amount 100 GB or so.

My project need:
The need is when I log off the system the windows service I have created should encrypt the folder(which is the folder with 100 GB data). And when I log in again it should decrypt it and make the folder usable.

So here comes my problem:
I am right now have a method which encrypts and decrypts files inside a folder in a loop format. So just imagine if I have a 100 GB or above in a folder while we log off or log in. The system may hang with such large amount of data.

What I want from you guys:
I am not asking for complete code from you guys. I need just an help.

Actually I want some code samples or something which helps me get rid of the problem. Also I am searching for the encrypting the folder on the whole instead of individual files inside.

I am looking for making this software similar to BITLOCKER. My service should handle the large files with ease.

What I have tried:

I have tried the below code:

protected void enCrypt(string filePath, string passWord)
        {
            //File.SetAttributes(filePath, FileAttributes.Normal);

            byte[] filestobeEncrypted = File.ReadAllBytes(filePath);
            byte[] passwordBytes = Encoding.UTF8.GetBytes(passWord);
            passwordBytes = SHA256.Create().ComputeHash(passwordBytes);

            byte[] bytesEncrypted = AES_Encrypt(filestobeEncrypted, passwordBytes);
            File.WriteAllBytes(filePath, bytesEncrypted);
        }

        protected void deCrypt(string filePath, string passWord)
        {
            //File.SetAttributes(filePath, FileAttributes.Normal);

            byte[] filestobeDecrypted = File.ReadAllBytes(filePath);
            byte[] passwordBytes = Encoding.UTF8.GetBytes(passWord);
            passwordBytes = SHA256.Create().ComputeHash(passwordBytes);

            byte[] bytesDecrypted = AES_Decrypt(filestobeDecrypted, passwordBytes);
            File.WriteAllBytes(filePath, bytesDecrypted);
        }

        public static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
        {
            byte[] encryptedBytes = null;

            // Set your salt here, change it to meet your flavor:
            // The salt bytes must be at least 8 bytes.
            byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

            using (MemoryStream ms = new MemoryStream())
            {
                using (RijndaelManaged AES = new RijndaelManaged())
                {
                    AES.KeySize = 256;
                    AES.BlockSize = 128;

                    var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
                    AES.Key = key.GetBytes(AES.KeySize / 8);
                    AES.IV = key.GetBytes(AES.BlockSize / 8);

                    AES.Mode = CipherMode.CBC;

                    using (var cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
                        cs.Close();
                    }
                    encryptedBytes = ms.ToArray();
                }
            }

            return encryptedBytes;
        }

        public static byte[] AES_Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
        {
            byte[] decryptedBytes = null;

            // Set your salt here, change it to meet your flavor:
            // The salt bytes must be at least 8 bytes.
            byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

            using (MemoryStream ms = new MemoryStream())
            {
                using (RijndaelManaged AES = new RijndaelManaged())
                {
                    AES.KeySize = 256;
                    AES.BlockSize = 128;

                    var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
                    AES.Key = key.GetBytes(AES.KeySize / 8);
                    AES.IV = key.GetBytes(AES.BlockSize / 8);

                    AES.Mode = CipherMode.CBC;

                    using (var cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
                        cs.Close();
                    }
                    decryptedBytes = ms.ToArray();
                }
            }

            return decryptedBytes;
        }