Web string encryption and decryption Methods

Using System;
Using System. Text;
Using System. Security;
Using System. Web. Security;

Namespace StringOperation
{
/// <Summary>
/// Summary of StringOperation.
/// </Summary>
Public class StringOperation
{
Public StringOperation ()
{
//
// TODO: add the constructor logic here
//
}
/// <Summary>
/// Convert special characters
/// </Summary>
/// <Param name = "str"> characters to be converted </param>
/// <Returns> </returns>
Public static string Encode (string str)
{
Str = str. Replace ("&", "& amp ;");
Str = str. Replace ("'","''");
Str = str. Replace ("\" "," & quot ;");
Str = str. Replace ("", "& nbsp ;");
Str = str. Replace ("<", "& lt ;");
Str = str. Replace (">", "& gt ;");
Str = str. Replace ("\ n", "<br> ");
Return str;
}

/// <Summary>
/// Decode
/// </Summary>
/// <Param name = "str"> string </param>
/// <Returns> </returns>
Public static string Decode (string str)
{
Str = str. Replace ("<br>", "\ n ");
Str = str. Replace ("& gt;", "> ");
Str = str. Replace ("& lt;", "<");
Str = str. Replace ("& nbsp ;","");
Str = str. Replace ("& quot ;","\"");
Return str;
}

/// <Summary>
/// Encrypting string
/// </Summary>
/// <Returns> </returns>
Public static string Encrypt (string Password)
{
String str = "";
FormsAuthenticationTicket ticket = new System. Web. Security. FormsAuthenticationTicket (Password, true, 2 );
Str = FormsAuthentication. Encrypt (ticket). ToString ();
Return str;
}

/// <Summary>
/// Encrypting string
/// </Summary>
/// <Param name = "Password"> encrypting string </param>
/// <Param name = "Format"> format, 0 is SHA1, 1 is MD5 </param>
/// <Returns> </returns>
Public static string Encrypt (string Password, int Format)
{
String str = "";
Switch (Format)
{
Case 0:
Str = FormsAuthentication. HashPasswordForStoringInConfigFile (Password, "SHA1 ");
Break;
Case 1:
Str = FormsAuthentication. HashPasswordForStoringInConfigFile (Password, "MD5 ");
Break;
}
Return str;
}

/// <Summary>
/// Decrypt string
/// </Summary>
/// <Param name = "Passowrd"> encrypted string </param>
/// <Returns> </returns>
Public static string Decrypt (string Passowrd)
{
String str = "";
Str = FormsAuthentication. Decrypt (Passowrd). Name. ToString ();
Return str;
}

/// <Summary>
/// Encrypt Cookie
/// </Summary>
/// <Param name = "str"> Target cookie string </param>
/// <Returns> </returns>
Public static string EncryptCookie (string strCookie, int type)
{
String str = En (strCookie, type );
StringBuilder sb = new StringBuilder ();
Foreach (char a in str)
{
Sb. Append (Convert. ToString (a, 16). PadLeft (4, '0 '));
}
Return sb. ToString ();
}

/// <Summary>
/// Decrypt Cookie
/// </Summary>
/// <Param name = "str"> Target cookie string </param>
/// <Returns> </returns>
Public static string DecryptCookie (string strCookie, int type)
{
StringBuilder sb = new StringBuilder ();
String [] strarr = new String [255];
Int I, j, count = strCookie. Length/4;
String strTmp;

For (I = 0; I <count; I ++)
{
For (j = 0; j <4; j ++)
{
Sb. Append (strCookie. Substring (I * 4 + j, 1 ));
}
Strarr [I] = sb. ToString ();
Sb. Remove (0, sb. Length );
}

For (I = 0; I <count; I ++)
{
StrTmp = uint. Parse (strarr [I], System. Globalization. NumberStyles. AllowHexSpecifier). ToString ("D ");
Char ch = (char) uint. Parse (strTmp );
Sb. Append (ch );
}

Return De (sb. ToString (), type );
}

Private static string En (string strCookie, int type)
{
String str;
If (type % 2 = 0)
{
Str = Transform1 (strCookie );
}
Else
{
Str = Transform3 (strCookie );
}

Str = Transform2 (strCookie );
Return str;
}

Private static string De (string strCookie, int type)
{
String str;
If (type % 2 = 0)
{
Str = DeTransform1 (strCookie );
}
Else
{
Str = DeTransform3 (strCookie );
}

Str = Transform2 (strCookie );
Return str;
}

/// <Summary>
/// Methods 1
/// </Summary>
/// <Param name = "str"> string </param>
/// <Returns> decrypted string </returns>
Public static string DeTransform1 (string str)
{
Int I = 0;
StringBuilder sb = new StringBuilder ();

Foreach (char a in str)
{
Switch (I % 6)
{
Case 0:
Sb. Append (char) (A-1 ));
Break;
Case 1:
Sb. Append (char) (A-5 ));
Break;
Case 2:
Sb. Append (char) (A-7 ));
Break;
Case 3:
Sb. Append (char) (A-2 ));
Break;
Case 4:
Sb. Append (char) (A-4 ));
Break;
Case 5:
Sb. Append (char) (a-9 ));
Break;
}
I ++;
}

Return sb. ToString ();
}

/// <Summary>
/// Method1
/// </Summary>
/// <Param name = "str"> string </param>
/// <Returns> encrypted string </returns>
Public static string Transform1 (string str)
{
Int I = 0;
StringBuilder sb = new StringBuilder ();

Foreach (char a in str)
{
Switch (I % 6)
{
Case 0:
Sb. Append (char) (a + 1 ));
Break;
Case 1:
Sb. Append (char) (a + 5 ));
Break;
Case 2:
Sb. Append (char) (a + 7 ));
Break;
Case 3:
Sb. Append (char) (a + 2 ));
Break;
Case 4:
Sb. Append (char) (a + 4 ));
Break;
Case 5:
Sb. Append (char) (a + 9 ));
Break;
}
I ++;
}

Return sb. ToString ();
}

/// <Summary>
/// Method1
/// </Summary>
/// <Param name = "str"> string </param>
/// <Returns> encrypted string </returns>
Public static string Transform2 (string str)
{
Uint j = 0;
StringBuilder sb = new StringBuilder ();

Str = Reverse (str );
Foreach (char a in str)
{
J =;
If (j> 255)
{
J = (uint) (a> 8) + (a & 0x0ff) <8 ));
}
Else
{
J = (uint) (a> 4) + (a & 0x0f) <4 ));
}
Sb. Append (char) j );
}

Return sb. ToString ();
}

/// <Summary>
/// Methods 1
/// </Summary>
/// <Param name = "str"> string </param>
/// <Returns> decrypted string </returns>
Public static string DeTransform3 (string str)
{
Int I = 0;
StringBuilder sb = new StringBuilder ();

Foreach (char a in str)
{
Switch (I % 6)
{
Case 0:
Sb. Append (char) (A-3 ));
Break;
Case 1:
Sb. Append (char) (A-6 ));
Break;
Case 2:
Sb. Append (char) (A-8 ));
Break;
Case 3:
Sb. Append (char) (A-7 ));
Break;
Case 4:
Sb. Append (char) (A-5 ));
Break;
Case 5:
Sb. Append (char) (A-2 ));
Break;
}
I ++;
}

Return sb. ToString ();
}

/// <Summary>
/// Method1
/// </Summary>
/// <Param name = "str"> string </param>
/// <Returns> encrypted string </returns>
Public static string Transform3 (string str)
{
Int I = 0;
StringBuilder sb = new StringBuilder ();

Foreach (char a in str)
{
Switch (I % 6)
{
Case 0:
Sb. Append (char) (a + 3 ));
Break;
Case 1:
Sb. Append (char) (a + 6 ));
Break;
Case 2:
Sb. Append (char) (a + 8 ));
Break;
Case 3:
Sb. Append (char) (a + 7 ));
Break;
Case 4:
Sb. Append (char) (a + 5 ));
Break;
Case 5:
Sb. Append (char) (a + 2 ));
Break;
}
I ++;
}

Return sb. ToString ();
}

/// <Summary>
/// Reverse display the specified character
/// </Summary>
/// <Param name = "str"> characters to be reversed </param>
/// <Returns> reverse character </returns>
Public static string Reverse (string str)
{
Int I;
StringBuilder sb = new StringBuilder ();

For (I = str. Length-1; I> = 0; I --)
{
Sb. Append (str [I]);
}

Return sb. ToString ();
}
}
}