using System;using System.Collections.Generic;using System.IO;using System.Linq;using System.Security.Cryptography;using System.Text;using System.Threading.Tasks;namespace ConsoleApplication1{    class Class1    {        private const string SKey = "_?73^?dVT3st5har3";        private const string SaltKey = "!2S@LT&KT3st5har3EY";        private const int Iterations = 1042; // Recommendation is >= 1000        static byte[] GetBytes(string str)        {            var bytes = new byte[str.Length * sizeof(char)];            Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);            return bytes;        }        static string GenerateKey()        {            // Create an instance of Symetric Algorithm. Key and IV is generated automatically.            DESCryptoServiceProvider desCrypto = (DESCryptoServiceProvider)DESCryptoServiceProvider.Create();            // Use the Automatically generated key for Encryption.             return ASCIIEncoding.ASCII.GetString(desCrypto.Key);        }        public static void EncryptFile(string srcFilename, string destFilename)        {            var aes = new AesManaged();            aes.BlockSize = 128;            aes.KeySize = 256;            var salt = GetBytes(SaltKey);            var key = new Rfc2898DeriveBytes(SKey, salt, Iterations);            aes.Key = key.GetBytes(aes.KeySize / 8);            aes.IV = key.GetBytes(aes.BlockSize / 8);            aes.Mode = CipherMode.CBC;            ICryptoTransform transform = aes.CreateEncryptor(aes.Key, aes.IV);            using (var dest = new FileStream(destFilename, FileMode.CreateNew, FileAccess.Write, FileShare.None))            {                using (var cryptoStream = new CryptoStream(dest, transform, CryptoStreamMode.Write))                {                    using (var source = new FileStream(srcFilename, FileMode.Open, FileAccess.Read, FileShare.Read))                    {                        source.CopyTo(cryptoStream);                    }                }            }        }        public static void DecryptFile(string srcFilename, string destFilename)        {            var aes = new AesManaged();            aes.BlockSize = 128;            aes.KeySize = 256;            var salt = GetBytes(SaltKey);            var key = new Rfc2898DeriveBytes(SKey, salt, Iterations);            aes.Key = key.GetBytes(aes.KeySize / 8);            aes.IV = key.GetBytes(aes.BlockSize / 8);            aes.Mode = CipherMode.CBC;            ICryptoTransform transform = aes.CreateDecryptor(aes.Key, aes.IV);            using (var dest = new FileStream(destFilename, FileMode.CreateNew, FileAccess.Write, FileShare.None))            {                using (var cryptoStream = new CryptoStream(dest, transform, CryptoStreamMode.Write))                {                    try                    {                        using (var source = new FileStream(srcFilename, FileMode.Open, FileAccess.Read, FileShare.Read))                        {                            source.CopyTo(cryptoStream);                        }                    }                    catch (CryptographicException exception)                    {                        throw new ApplicationException("Decryption failed.", exception);                    }                }            }        }    }}

    static void Main(string[] args)        {           // Class1.EncryptFile(@"C:\kc_Page_2.mp4", @"C:\kc_Page_3.mp4");            //Class1.DecryptFile(@"C:\kc_Page_3.mp4", @"C:\kc_Page_4.mp4");            Class1.EncryptFile(@"C:\1.docx", @"C:\2.docx");            Class1.DecryptFile(@"C:\2.docx", @"C:\3.docx");            }