Encryption and Decryption Functions

Microsoft provides very good classes for encryption and decryption under the following namespace.
System.Security.Cryptography.
Coding Sample Given as follows:

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;
using System.Security.Cryptography;

///

/// Class which contains static reusable methods for encrypting a string.
/// Mainly constructed for URL encryption but further can be used for string encryption
/// needed in other operation.
///

public class Cryptex
{
public Cryptex()
{
//
// TODO: Add constructor logic here
//
}

internal static HttpServerUtility sUtil = HttpContext.Current.Server;

///

/// Method used to encrypt a string making use of DES Algorithm.
///

///
///
///
public static string StringEncrypt_DES(string queryString) {

DESCryptoServiceProvider des = new DESCryptoServiceProvider();
string key = ConfigurationManager.AppSettings["DESCryptokey"];

des.Key = Encoding.UTF8.GetBytes(key.Substring(0, 8));
des.IV = Encoding.UTF8.GetBytes(key.Substring(0, 8));
ICryptoTransform cryptotransform = des.CreateEncryptor();
try {
MemoryStream mStream = new MemoryStream();
CryptoStream cryptostream = new CryptoStream(mStream, cryptotransform, CryptoStreamMode.Write);
StreamWriter writer = new StreamWriter(cryptostream);

writer.WriteLine(queryString);
writer.Close();
cryptostream.Close();

byte[] buffer = mStream.ToArray();
mStream.Close();
return Convert.ToBase64String(buffer);
}
catch {
throw;
}
return string.Empty;
}

///

/// Method used to dencrypt a string making use of DES Algorithm.
///

///
///
///
public static string StringDecrypt_DES(string queryString) {

DESCryptoServiceProvider des = new DESCryptoServiceProvider();
string key = ConfigurationManager.AppSettings["DESCryptokey"];

des.Key = Encoding.UTF8.GetBytes(key.Substring(0, 8));
des.IV = Encoding.UTF8.GetBytes(key.Substring(0, 8));
try {
queryString = sUtil.UrlDecode(queryString);

byte[] buffer = Convert.FromBase64String(queryString.Trim());

MemoryStream mStream = new MemoryStream(buffer);
ICryptoTransform cryptotransform = des.CreateDecryptor();
CryptoStream cryptostream = new CryptoStream(mStream, cryptotransform, CryptoStreamMode.Read);

StreamReader reader = new StreamReader(cryptostream);

queryString = reader.ReadLine();
reader.Close();
cryptostream.Close();
mStream.Close();
}
catch {
throw;
}
return queryString;
}

///

/// Method used to encrypt a string making use of RC2 Algorithm.
///

///
///
///
public static string StringEncrypt_RC2(string inputString, string key) {

RC2CryptoServiceProvider rc2 = new RC2CryptoServiceProvider();
rc2.Mode = CipherMode.CBC;

rc2.Key = ASCIIEncoding.ASCII.GetBytes(key);
rc2.IV = ASCIIEncoding.ASCII.GetBytes(key);
ICryptoTransform cryptotransform = rc2.CreateEncryptor();
return encrypt(inputString, cryptotransform);
}
///

/// Method used to dencrypt a string making use of RC2 Algorithm.
///

///
///
///
public static string StringDecrypt_RC2(string inputString, string key) {

RC2CryptoServiceProvider rc2 = new RC2CryptoServiceProvider();
rc2.Mode = CipherMode.CBC;

rc2.Key = ASCIIEncoding.ASCII.GetBytes(key);
rc2.IV = ASCIIEncoding.ASCII.GetBytes(key);
ICryptoTransform cryptotransform = rc2.CreateDecryptor();
return decrypt(inputString, cryptotransform);
}
///

/// Method used to encrypt a string making use of Rijndael Algorithm.
///

///
///
///
public static string StringEncrypt_RIJNDAEL(string inputString, string key) {

Rijndael rijndael = new RijndaelManaged();
rijndael.Mode = CipherMode.CBC;
rijndael.Key = ASCIIEncoding.ASCII.GetBytes(key);
rijndael.IV = ASCIIEncoding.ASCII.GetBytes(key);
ICryptoTransform cryptotransform = rijndael.CreateEncryptor();
return encrypt(inputString, cryptotransform);
}

///

/// Method used to dencrypt a string making use of Rijndael Algorithm.
///

///
///
///
public static string StringDecrypt_RIJNDAEL(string inputString, string key) {

Rijndael rijndael = new RijndaelManaged();
rijndael.Mode = CipherMode.CBC;
rijndael.Key = ASCIIEncoding.ASCII.GetBytes(key);
rijndael.IV = ASCIIEncoding.ASCII.GetBytes(key);
ICryptoTransform cryptotransform = rijndael.CreateDecryptor();
return decrypt(inputString, cryptotransform);
}

protected static string encrypt(string Str, ICryptoTransform cryptotransform) {
try {
MemoryStream mStream = new MemoryStream();
CryptoStream cryptostream = new CryptoStream(mStream, cryptotransform, CryptoStreamMode.Write);
StreamWriter writer = new StreamWriter(cryptostream);

writer.WriteLine(Str.Trim());
writer.Close();
cryptostream.Close();

byte[] buffer = mStream.ToArray();
mStream.Close();
Str = sUtil.UrlEncode(Convert.ToBase64String(buffer));
}
catch{
throw;
}
return Str;
}

protected static string decrypt(string Str, ICryptoTransform cryptotransform) {
try {
Str = sUtil.UrlDecode(Str.Trim());
byte[] buffer = Convert.FromBase64String(Str);

MemoryStream mStream = new MemoryStream(buffer);
CryptoStream cryptostream = new CryptoStream(mStream, cryptotransform, CryptoStreamMode.Read);
StreamReader reader = new StreamReader(cryptostream);
Str = reader.ReadLine();
reader.Close();
cryptostream.Close();
mStream.Close();
}
catch {
throw;
}
return Str;
}

const string DESKey = "AQWSEDRF";
const string DESIV = "AQWSEDRF";

public static string DESDecrypt(string stringToDecrypt)//Decrypt the content
{
byte[] key;
byte[] IV;

byte[] inputByteArray;
try {
key = Convert2ByteArray(DESKey);
IV = Convert2ByteArray(DESIV);
int len = stringToDecrypt.Length; inputByteArray = Convert.FromBase64String(stringToDecrypt);
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
MemoryStream ms = new MemoryStream();
CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(key, IV), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
Encoding encoding = Encoding.UTF8; return encoding.GetString(ms.ToArray());
}
catch (System.Exception ex) {
throw ex;
}
}

public static string DESEncrypt(string stringToEncrypt)// Encrypt the content
{
byte[] key;
byte[] IV;

byte[] inputByteArray;
try {
key = Convert2ByteArray(DESKey);
IV = Convert2ByteArray(DESIV);
inputByteArray = Encoding.UTF8.GetBytes(stringToEncrypt);
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
MemoryStream ms = new MemoryStream(); CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(key, IV), CryptoStreamMode.Write);
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
return Convert.ToBase64String(ms.ToArray());
}
catch (System.Exception ex) {
throw ex;
}
}

static byte[] Convert2ByteArray(string strInput) {

int intCounter; char[] arrChar;
arrChar = strInput.ToCharArray();
byte[] arrByte = new byte[arrChar.Length];
for (intCounter = 0; intCounter <= arrByte.Length - 1; intCounter++)
arrByte[intCounter] = Convert.ToByte(arrChar[intCounter]);
return arrByte;
}
}



For More Info Follow Following Link :

http://msdn.microsoft.com/en-us/library/system.security.cryptography.asnencodeddataenumerator.aspx