using System;
/*
Class  : StringCrypt.cs
Aurthor: Departure
Url    : im-integrations.com
Info:
Encrypt Strings with Vigenere Cipher and ROT Cipher(Caesar Cipher, Rot13 ect..)
Based on information from wiki
*/
 
internal class StringCrypt
{
public static string Vigenere(string sSource, string sKey, int iTableSize = 94, bool bDecrypt = false)
{
//Variables
int i = 32;
int iPosText;
int iPosKey;
string sTable = "";
string sResult = "";
 
//Create Table
while (i < (iTableSize + 32))             {                 sTable +=  ((char)i);                 i++;             }             //Make Key same size as Cipher             while (sSource.Length >= sKey.Length)
{
sKey = string.Concat(sKey, sKey);
}
 
//Vigenere Routine
i = 0;
while (i <= (sSource.Length - 1))
{
if (sTable.IndexOf(sSource[i]) == -1)
sResult += sSource[i];
else
{
iPosText = sTable.IndexOf(sSource[i]);
iPosKey = sTable.IndexOf(sKey[i]);
if (bDecrypt)
sResult += sTable[(((iPosText + iTableSize) - iPosKey) % iTableSize)];
else
sResult += sTable[((iPosText + iPosKey) % iTableSize)];
}
i++;
 
}
 
return sResult;
 
}
 
public static string Caesar(string sSource, int iKey, bool bDecrypt = false)
{
//Variables
string sResult = "";
string sTable = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
int iPosText;
int i;
 
//Convert to Uppercase
sSource = sSource.ToUpper();
 
//Caesar Routine
i = 0;
while (i <= (sSource.Length - 1))
{
if (sTable.IndexOf(sSource[i]) == -1)
sResult += sSource[i];
else
{
iPosText = sTable.IndexOf(sSource[i]);
if (bDecrypt)
sResult += sTable[(((iPosText + sTable.Length) - iKey) % sTable.Length)];
else
 
sResult += sTable[((iPosText + iKey) % sTable.Length)];
}
i++;
}
 
return sResult;
 
}
 
public static string ROT13(string sSource)
{
return Caesar(sSource, 13, false);
}
}

Function CaesarLeft(sString: String; iAmount: Integer):String;
var
 i, iPos: Integer;
 sAlphabet: String;
begin
 sAlphabet:= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
 i:= 1;
 while i <= Length(sString) do
  Begin
   if sString[i] = ' ' then
    Result:= Result + ' '
    else
    begin
     iPos:= pred(pos(sString[i],sAlphabet));
     Result:= Result + sAlphabet[(((iPos + 26) - iAmount) mod 26) + 1];
    end;
   inc(i);
  end;
end;
 
Function CaesarRight(sString: String; iAmount: Integer):String;
var
 i, iPos: Integer;
 sAlphabet: String;
begin
 sAlphabet:= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
 i:= 1;
 while i <= Length(sString) do
  Begin
   if sString[i] = ' ' then
    Result:= Result + ' '
    else
    begin
     iPos:= pred(pos(sString[i],sAlphabet));
     Result:= Result + sAlphabet[((iPos + iAmount) mod 26) + 1];
    end;
   inc(i);
 end;
end;

Function VigenereDecrypt(sEncrypted, sKey: String): String;
var
 i, iPosCipher, iPosKey: Integer;
 sString: string;
begin
//Create our Cipher Table
 sString:= 'abcdefghijklmnopqrstuvwxyz';
//Make the key the same size or greater than the Cipher
 while Length(sEncrypted) >= Length(sKey) do
   sKey:= AnsiLowercase(sKey) + AnsiLowercase(sKey);
//Remove Spaces from Cipher
 i:=0;
  while i<=Length(sEncrypted) do
    if sEncrypted[i]=' ' then Delete(sEncrypted, i, 1)
    else Inc(i);
//Vegenere Decryption routine
 i:= 1;
  while i <= Length(sEncrypted) do
   Begin
    iPosCipher:= pred(pos(sEncrypted[i],sString));
    iPosKey   := pred(pos(sKey[i],sString));
    Result    := Result + sString[(((iPosCipher + 26) - iPosKey) mod 26) + 1];
    inc(i);
   end;
end;
 
Function VigenereEncrypt(sPlainText, sKey: String): String;
var
 i, iPosText, iPosKey: Integer;
 sString: string;
begin
//Create our Cipher Table
 sString:= 'abcdefghijklmnopqrstuvwxyz';
//Make the key the same size or greater than the Plain Text
 while Length(sPlainText) >= Length(sKey) do
   sKey:= AnsiLowercase(sKey) + AnsiLowercase(sKey);
//Remove Spaces from Cipher
 i:=0;
  while i<=Length(sPlainText) do
    if sPlainText[i]=' ' then Delete(sPlainText, i, 1)
    else Inc(i);
//Vegenere Encryption routine
 i:= 1;
  while i <= Length(sPlainText) do
   Begin
    iPosText:= pred(pos(sPlainText[i],sString));
    iPosKey   := pred(pos(sKey[i],sString));
    Result    := Result + sString[((iPosText  + iPosKey) mod 26) + 1];
    inc(i);
   end;
end;