//-----------------------------------------------------------------------
//  This file is part of the Microsoft .NET Framework SDK Code Samples.
// 
//  Copyright (C) Microsoft Corporation.  All rights reserved.
// 
//This source code is intended only as a supplement to Microsoft
//Development Tools and/or on-line documentation.  See these other
//materials for detailed information regarding Microsoft code samples.
// 
//THIS CODE AND INFORMATION ARE PROVIDED AS IS WITHOUT WARRANTY OF ANY
//KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
//IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
//PARTICULAR PURPOSE.
//-----------------------------------------------------------------------
using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace Microsoft.Samples.Cryptography.FileEncryptCS
{
	class FileEncrypt 
	{

		public static Byte[] ConvertStringToByteArray(String s)
		{
			return (new UnicodeEncoding()).GetBytes(s);
		}

		public static void Main()
		{
			//Creating a file stream
			FileStream fs  = new FileStream("EncryptedFile.txt",FileMode.Create,FileAccess.Write);

			Console.WriteLine("Enter Some Text to be stored in encrypted file:");
			String strinput = Console.ReadLine();

			Byte[] bytearrayinput=ConvertStringToByteArray(strinput);

			//DES instance with random key
			DESCryptoServiceProvider des = new DESCryptoServiceProvider();
			//create DES Encryptor from this instance
			ICryptoTransform desencrypt = des.CreateEncryptor();

			//Create Crypto Stream that transforms file stream using des encryption
			CryptoStream cryptostream = new CryptoStream(fs,desencrypt,CryptoStreamMode.Write);

			//write out DES encrypted file
			cryptostream.Write(bytearrayinput,0,bytearrayinput.Length);

			cryptostream.Close();

			//create file stream to read encrypted file back
			FileStream fsread = new FileStream("EncryptedFile.txt",FileMode.Open,FileAccess.Read);

			//create DES Decryptor from our des instance
			ICryptoTransform desdecrypt = des.CreateDecryptor();

			//create crypto stream set to read and do a des decryption transform on incoming bytes
			CryptoStream cryptostreamDecr = new CryptoStream(fsread,desdecrypt,CryptoStreamMode.Read);
			//print out the contents of the decrypted file
			Console.WriteLine( (new StreamReader(cryptostreamDecr, new UnicodeEncoding())).ReadToEnd() );

			Console.WriteLine ();
			Console.WriteLine ("Press Enter to continue...");
			Console.ReadLine();
		}
	}
}