using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Security.Cryptography; // needed for the encryption classes

using System.IO; // needed for the MemoryStream

using System.Text; // needed for the UTF8 encoding

using System.Net; // needed for the cookie

namespace Misc

{

public partial class EncryptionExample1 : System.Web.UI.Page

{

private Byte[] key = { 250, 101, 18, 76, 45, 135, 207, 118, 4, 171, 3, 168, 202, 241, 37, 199 };

private Byte[] vector = { 146, 64, 191, 111, 23, 3, 113, 119, 231, 121, 252, 112, 79, 32, 114, 156 };

protected void Page_Load(object sender, EventArgs e)

{

// Read encrypted password from cookie

if (!IsPostBack && Request.Cookies["LoginCookie"] != null)

{

HttpCookie myCookie = Request.Cookies["LoginCookie"];

txtUserName.Text = myCookie.Values["Username"];

txtPassword.Text = myCookie.Values["Password"];

lblDisplay.Text = "Data read from cookie.";

}

}

protected void btnEncrypt_Click(object sender, EventArgs e)

{

String user = txtUserName.Text;

String plainTextPassword = txtPassword.Text;

String encryptedPassword;

UTF8Encoding encoder = new UTF8Encoding(); // used to convert bytes to characters, and back

Byte[] textBytes; // stores the plain text data as bytes

// Perform Encryption

//-------------------

// Convert a string to a byte array, which will be used in the encryption process.

textBytes = encoder.GetBytes(plainTextPassword);

// Create an instances of the encryption algorithm (Rinjdael AES) for the encryption to perform,

// a memory stream used to store the encrypted data temporarily, and

// a crypto stream that performs the encryption algorithm.

RijndaelManaged rmEncryption = new RijndaelManaged();

MemoryStream myMemoryStream = new MemoryStream();

CryptoStream myEncryptionStream = new CryptoStream(myMemoryStream, rmEncryption.CreateEncryptor(key, vector), CryptoStreamMode.Write);

// Use the crypto stream to perform the encryption on the plain text byte array.

myEncryptionStream.Write(textBytes, 0, textBytes.Length);

myEncryptionStream.FlushFinalBlock();

// Retrieve the encrypted data from the memory stream, and write it to a separate byte array.

myMemoryStream.Position = 0;

Byte[] encryptedBytes = new Byte[myMemoryStream.Length];

myMemoryStream.Read(encryptedBytes, 0, encryptedBytes.Length);

// Close all the streams.

myEncryptionStream.Close();

myMemoryStream.Close();

// Convert the bytes to a string and display it.

encryptedPassword = Convert.ToBase64String(encryptedBytes);

lblDisplay.Text = encryptedPassword;

divMethod.InnerText = "Encrypted Data:";

// Write encrypted password to a cookie

HttpCookie myCookie = new HttpCookie("LoginCookie");

myCookie.Values["Username"] = user;

myCookie.Values["Password"] = encryptedPassword;

myCookie.Expires = new DateTime(2020, 2, 1);

Response.Cookies.Add(myCookie);

}

protected void btnDecrypt_Click(object sender, EventArgs e)

{

// Read encrypted password from cookie

if (Request.Cookies["LoginCookie"] != null)

{

HttpCookie myCookie = Request.Cookies["LoginCookie"];

String encryptedPassword = myCookie.Values["Password"];

Byte[] encryptedPasswordBytes = Convert.FromBase64String(encryptedPassword);

Byte[] textBytes;

String plainTextPassword;

UTF8Encoding encoder = new UTF8Encoding();

// Perform Decryption

//-------------------

// Create an instances of the decryption algorithm (Rinjdael AES) for the encryption to perform,

// a memory stream used to store the decrypted data temporarily, and

// a crypto stream that performs the decryption algorithm.

RijndaelManaged rmEncryption = new RijndaelManaged();

MemoryStream myMemoryStream = new MemoryStream();

CryptoStream myDecryptionStream = new CryptoStream(myMemoryStream, rmEncryption.CreateDecryptor(key, vector), CryptoStreamMode.Write);

// Use the crypto stream to perform the decryption on the encrypted data in the byte array.

myDecryptionStream.Write(encryptedPasswordBytes, 0, encryptedPasswordBytes.Length);

myDecryptionStream.FlushFinalBlock();

// Retrieve the decrypted data from the memory stream, and write it to a separate byte array.

myMemoryStream.Position = 0;

textBytes = new Byte[myMemoryStream.Length];

myMemoryStream.Read(textBytes, 0, textBytes.Length);

// Close all the streams.

myDecryptionStream.Close();

myMemoryStream.Close();

// Convert the bytes to a string and display it.

plainTextPassword = encoder.GetString(textBytes);

lblDisplay.Text = plainTextPassword;

txtPassword.Text = plainTextPassword;

divMethod.InnerText = "Decrypted Data:";

}

}

}

}