Class implements encryption and decryption under the. NET Framework

using system;
using system. data;
using system. configuration;
using system. web;
using system. web. security;
using system. web. ui;
using system. web. UI. webcontrols;
using system. web. UI. webcontrols. webparts;
using system. web. UI. htmlcontrols;
using system. security. cryptography;
using system. io;
using system. text;

//

// Security summary
// security class implements encryption and decryption under the. NET Framework.
//
namespace ptfair. websites. common
{< br> public class security
{< br> string _ querystringkey = configurationsettings. deleetask[ "cryptionkey"]; // URL transmission parameter encryption key
string _ passwordkey = "hgfedcba"; // password encryption key
Public Security ()
{< br> //
// todo: add the constructor logic here
//
}

///
/// Encrypted URL transmission string
///
Public String encryptquerystring (string querystring)
{
Return encrypt (querystring, _ querystringkey );
}

///
/// Decrypt the string transmitted by the URL
///
Public String decryptquerystring (string querystring)
{
Return decrypt (querystring, _ querystringkey );
}

///
/// Encrypted account password
///
Public String encryptpassword (string password)
{
Return encrypt (password, _ passwordkey );
}

///
/// Decrypt the account password
///
Public String decryptpassword (string password)
{
Return decrypt (password, _ passwordkey );
}

///
/// Dec encryption process
///
Public String encrypt (string ptoencrypt, string skey)
{
Descryptoserviceprovider des = new descryptoserviceprovider (); // put the string in the byte array

Byte [] inputbytearray = encoding. Default. getbytes (ptoencrypt );
// Byte [] inputbytearray = encoding. Unicode. getbytes (ptoencrypt );
Des. Key = asciiencoding. ASCII. getbytes (skey); // create the key and offset of the encryption object
Des. IV = asciiencoding. ASCII. getbytes (skey); // use the getbytes method of the asciiencoding. ASCII method in the original article
Memorystream MS = new memorystream (); // enables the input password to be in English text
Cryptostream cs = new cryptostream (MS, Des. createencryptor (), cryptostreammode. Write );
CS. Write (inputbytearray, 0, inputbytearray. Length );
CS. flushfinalblock ();
Stringbuilder ret = new stringbuilder ();
Foreach (byte B in ms. toarray ())
{
Ret. appendformat ("{0: X2}", B );
}

Ret. tostring ();
Return ret. tostring ();
}

///
/// Dec decryption process
///
Public String decrypt (string ptodecrypt, string skey)
{
Descryptoserviceprovider des = new descryptoserviceprovider ();
Int Len = ptodecrypt. Length/2;
Byte [] inputbytearray = new byte [Len];
For (INT x = 0; x <Len; X ++)
{
Int I = (convert. toint32 (ptodecrypt. substring (x * 2, 2), 16 ));
Inputbytearray [x] = (byte) I;
}
Des. Key = asciiencoding. ASCII. getbytes (skey); // create the key and offset of the encryption object. This value is important and cannot be modified.
Des. IV = asciiencoding. ASCII. getbytes (skey );
Memorystream MS = new memorystream ();
Cryptostream cs = new cryptostream (MS, Des. createdecryptor (), cryptostreammode. Write );
CS. Write (inputbytearray, 0, inputbytearray. Length );
CS. flushfinalblock ();
Stringbuilder ret = new stringbuilder (); // create a stringbuild object. createdecrypt uses a stream object and the decrypted text must be converted into a stream object.
Return System. Text. encoding. Default. getstring (Ms. toarray ());
}

///
/// Check whether the encrypted string is the same as the original one
///
Public bool validatestring (string enstring, string fostring, int Mode)
{
Switch (Mode)
{
Default:
Case 1:
If (decrypt (enstring, _ querystringkey) = fostring. tostring ())
{
Return true;
}
Else
{
Return false;
}
Case 2:
If (decrypt (enstring, _ passwordkey) = fostring. tostring ())
{
Return true;
}
Else
{
Return false;
}
}
}
}
}