Create playfaircipher.cpp

Algorithms/playfaircipher.cpp

@@ -0,0 +1,126 @@
+#include <iostream>
+#include <string>
+using namespace std;
+class playfair {
+   public:
+      string msg; char n[5][5];
+   void play( string k, string t, bool m, bool e ) {
+      createEncoder( k, m );
+      getText( t, m, e );
+      if( e )
+         play( 1 );
+      else
+         play( -1 );
+      print();
+   }
+   private:
+      void play( int dir ) {
+      int j,k,p,q;
+      string nmsg;
+      for( string::const_iterator it = msg.begin(); it != msg.end(); it++ ) {
+         if( getPos( *it++, j, k ) )
+         if( getPos( *it, p, q) {
+            //for same row
+            if( j == p ) {
+               nmsg+= getChar( j, k + dir );
+               nmsg += getChar( p, q + dir );
+            }
+            //for same column
+            else if( k == q ) {
+               nmsg += getChar( j + dir, k );
+               nmsg += getChar( p + dir, q );
+            } else {
+               nmsg += getChar( p, k );
+               nmsg += getChar( j, q );
+            }
+         }
+      }
+      msg = nmsg;
+   }
+   void print() //print the solution {
+      cout << "\n\n Solution:" << endl;
+      string::iterator it = msg.begin(); int count = 0;
+      while( it != msg.end() ) {
+         cout << *it;
+         it++;
+         cout << *it << " ";
+         it++;
+         if( ++count >= 26 )
+         cout << endl;
+         count = 0;
+      }
+      cout << endl << endl;
+   }
+   char getChar( int a, int b ) { //get the characters
+      return n[ (b + 5) % 5 ][ (a + 5) % 5 ];
+   }
+   bool getPos( char l, int &c, int &d ) { //get the position
+      for( int y = 0; y < 5; y++ )
+      for( int x = 0; x < 5; x++ )
+      if( n[y][x] == l ) {
+         c = x;
+         d= y;
+      return true;
+      }
+      return false;
+   }
+   void getText( string t, bool m, bool e ) { //get the original message
+      for( string::iterator it = t.begin(); it != t.end(); it++ ) {
+         //to choose J = I or no Q in the alphabet.
+         *it = toupper( *it );
+         if( *it < 65 || *it > 90 )
+            continue;
+         if( *it == 'J' && m )
+            *it = 'I';
+         else if( *it == 'Q' && !m )
+            continue;
+         msg += *it;
+      }  
+      if( e ) {
+         string nmsg = ""; size_t len = msg.length();
+         for( size_t x = 0; x < len; x += 2 ) {
+            nmsg += msg[x];
+            if( x + 1 < len ) {
+               if( msg[x] == msg[x + 1] ) nmsg += 'X';
+               nmsg += msg[x + 1];
+            }
+         }
+         msg = nmsg;
+      }
+      if( msg.length() & 1 )
+      msg += 'X';
+   }
+   void createEncoder( string key, bool m ) { //creation of the key table
+      if( key.length() < 1 )
+      key= "KEYWORD";
+      key += "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+      string s= "";
+      for( string::iterator it = key.begin(); it != key.end(); it++ ) {
+         *it = toupper( *it );
+         if( *it < 65 || *it > 90 )
+            continue;
+         if( ( *it == 'J' && m ) || ( *it == 'Q' && !m ) )
+            continue;
+         if( s.find( *it ) == -1 )
+            s += *it;
+      }
+      copy( s.begin(), s.end(), &n[0][0] );
+   }
+};
+int main( int argc, char* argv[] ) {
+   string k, i, msg;
+   bool m, c;
+   cout << "Encrpty or Decypt? ";
+   getline( cin, i );
+   c = ( i[0] == 'e' || i[0] == 'E' );
+   cout << "Enter a key: ";
+   getline( cin, k);
+   cout << "I <-> J (Y/N): ";
+   getline( cin, i );
+   m = ( i[0] == 'y' || i[0] == 'Y' );
+   cout << "Enter the message: ";
+   getline( cin, msg );
+   playfair pf;
+   pf.play( k, msg,m, c );
+   return system( "pause" );
+}