Encryption , Decryption in

/*
* Author : Nidheesh T.Mani
* Version : 1.0
*/

using System;
using System.Security.Cryptography;
namespace Utils
{
///

/// This class provide static methods for encryption and decryption.
///

public class DataEncryption
{
///

/// Method which does the encryption using Rijndeal algorithm
///

/// Data to be encrypted
/// The string to used for making the key.The same string
/// should be used for making the decrpt key
/// Encrypted Data
public static string EncryptString ( string InputText, string Password )
{
RijndaelManaged RijndaelCipher = new RijndaelManaged ( );

byte [ ] PlainText = System.Text.Encoding.Unicode.GetBytes ( InputText );
byte [ ] Salt = System.Text.Encoding.ASCII.GetBytes ( Password.Length.ToString ( ) );

//This class uses an extension of the PBKDF1 algorithm defined in the PKCS#5 v2.0
//standard to derive bytes suitable for use as key material from a password.
//The standard is documented in IETF RRC 2898.

PasswordDeriveBytes SecretKey = new PasswordDeriveBytes ( Password, Salt );
//Creates a symmetric encryptor object.
ICryptoTransform Encryptor = RijndaelCipher.CreateEncryptor ( SecretKey.GetBytes ( 32 ), SecretKey.GetBytes ( 16 ) );
System.IO.MemoryStream memoryStream = new System.IO.MemoryStream ( );
//Defines a stream that links data streams to cryptographic transformations
CryptoStream cryptoStream = new CryptoStream ( memoryStream, Encryptor, CryptoStreamMode.Write );
cryptoStream.Write ( PlainText, 0, PlainText.Length );
//Writes the final state and clears the buffer
cryptoStream.FlushFinalBlock ( );
byte [ ] CipherBytes = memoryStream.ToArray ( );
memoryStream.Close ( );
cryptoStream.Close ( );
string EncryptedData = Convert.ToBase64String ( CipherBytes );
return EncryptedData;

} //eof private static string EncryptString ( string InputText, string Password )

///

/// Method which does the encryption using Rijndeal algorithm.This is for decrypting the data
/// which has orginally being encrypted using the above method
///

/// The encrypted data which has to be decrypted
/// The string which has been used for encrypting.The same string
/// should be used for making the decrypt key
/// Decrypted Data
public static string DecryptString ( string InputText, string Password )
{

RijndaelManaged RijndaelCipher = new RijndaelManaged ( );
byte [ ] EncryptedData = Convert.FromBase64String ( InputText );
byte [ ] Salt = System.Text.Encoding.ASCII.GetBytes ( Password.Length.ToString ( ) );
//Making of the key for decryption
PasswordDeriveBytes SecretKey = new PasswordDeriveBytes ( Password, Salt );
//Creates a symmetric Rijndael decryptor object.
ICryptoTransform Decryptor = RijndaelCipher.CreateDecryptor ( SecretKey.GetBytes ( 32 ), SecretKey.GetBytes ( 16 ) );
System.IO.MemoryStream memoryStream = new System.IO.MemoryStream ( EncryptedData );
//Defines the cryptographics stream for decryption.THe stream contains decrpted data
CryptoStream cryptoStream = new CryptoStream ( memoryStream, Decryptor, CryptoStreamMode.Read );
byte [ ] PlainText = new byte [ EncryptedData.Length ];
int DecryptedCount = cryptoStream.Read ( PlainText, 0, PlainText.Length );
memoryStream.Close ( );
cryptoStream.Close ( );
//Converting to string
string DecryptedData = System.Text.Encoding.Unicode.GetString ( PlainText, 0, DecryptedCount );
return DecryptedData;

} //eof private static string DecryptString (string InputText , string Password )

} //eof class

} //eof namespace Utils