aes_encrypt.cs

public static void AES_Encrypt(string inputFile, string password)
{
    //Source: http://stackoverflow.com/questions/14871238/report-progress-backgroundworker-from-different-class-c-sharp
    //Source: http://stackoverflow.com/questions/27645527/aes-encryption-on-large-files

    //generate random salt
    byte[] salt = Security.GenerateRandomSalt(32);

    //create output file name
    FileStream fsCrypt = new FileStream(inputFile + ".aes", FileMode.Create);

    //convert password string to byte arrray
    byte[] passwordBytes = System.Text.Encoding.UTF8.GetBytes(password);

    //Set Rijndael symmetric encryption algorithm
    RijndaelManaged AES = new RijndaelManaged();

    AES.KeySize = 256;
    AES.BlockSize = 128;
    AES.Padding = PaddingMode.PKCS7;

    //http://stackoverflow.com/questions/2659214/why-do-i-need-to-use-the-rfc2898derivebytes-class-in-net-instead-of-directly
    //"What it does is repeatedly hash the user password along with the salt."
    //High iteration counts.

    var key = new Rfc2898DeriveBytes(passwordBytes, salt, 50000);
    AES.Key = key.GetBytes(AES.KeySize / 8);
    AES.IV = key.GetBytes(AES.BlockSize / 8);

    //Cipher modes: 
    //http://security.stackexchange.com/questions/52665/which-is-the-best-cipher-mode-and-padding-mode-for-aes-encryption
    AES.Mode = CipherMode.CFB;

    //write salt to the begining of the output file
    fsCrypt.Write(salt, 0, salt.Length);

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

    FileStream fsIn = new FileStream(inputFile, FileMode.Open);

    //create a buffer (1mb) so only this amount will allocate in the memory and not the whole file
    byte[] buffer = new byte[1048576];
    int read;
    long y = 0;

    try
    {
        while ((read = fsIn.Read(buffer, 0, buffer.Length)) > 0)
        {
            Application.DoEvents();
            // -> for responsive GUI, using Task will be better!
            //JSEncryptorPro uses background worker, I left it here like this, so if somebody
            //want to "copy-paste" the code, can use immediately

            cs.Write(buffer, 0, read);
        }
        //close up
        fsIn.Close();
    }
    catch (Exception ex)
    {
        Debug.WriteLine("Error: " + ex.Message);
    }
    finally
    {
        cs.Close();
        fsCrypt.Close();
    }
}