Ejemplo n.º 1
0
        static string decrypt(String encryptedString, Playfair cipher)
        {
            encryptedString = encryptedString.ToLower();
            string decryptedString = null;

            List <Plain> listPlains = new List <Plain>();

            for (int c = 1; c < encryptedString.Length; c++)
            {
                if (c % 2 == 1)
                {
                    Plain plain = new Plain();

                    plain.setval1(encryptedString[c - 1]);
                    plain.setval2(encryptedString[c]);

                    listPlains.Add(plain);
                }
            }



            List <Plain> listDecrypted = new List <Plain>();

            foreach (Plain p in listPlains)
            {
                p.findCoordinates(cipher);
                if (p.getx1() == p.getx2())  //ten sam wiersz
                {
                    if (p.gety1() == 0)
                    {
                        p.sety2(p.gety2() - 1);
                        p.sety1(4);
                    }
                    else if (p.gety2() == 0)
                    {
                        p.sety2(4);
                        p.sety1(p.gety2() - 1);
                    }
                    else
                    {
                        p.sety1(p.gety1() - 1);
                        p.sety2(p.gety2() - 1);
                    }
                }
                else if (p.gety1() == p.gety2())  //ta sama kolumna
                {
                    if (p.getx2() == 0)
                    {
                        p.setx2(4);
                        p.setx1(p.getx1() - 1);
                    }
                    else if (p.getx1() == 0)
                    {
                        p.setx2(p.getx2() - 1);
                        p.setx1(4);
                    }
                    else
                    {
                        p.setx1(p.getx1() - 1);
                        p.setx2(p.getx2() - 1);
                    }
                }
                else                                    ///reszta
                {
                    int buf = p.gety1();
                    p.sety1(p.gety2());
                    p.sety2(buf);
                }

                p.findCipherLetters(cipher);

                listDecrypted.Add(p);
            }
            foreach (Plain p in listDecrypted)
            {
                decryptedString = decryptedString + string.Join("", p.getval1().ToString()) + string.Join("", p.getval2().ToString());
            }
            for (int c = 1; c < decryptedString.Length - 1; c++)
            {
                if (c > 0 && c < decryptedString.Length)
                {
                    if (decryptedString[c] == 'x' && decryptedString[c - 1] == decryptedString[c + 1])
                    {
                        decryptedString = decryptedString.Replace("x", "");
                    }
                }
            }


            return(decryptedString);
        }
Ejemplo n.º 2
0
        static string encrypt(String text, Playfair cipher)
        {
            text = text.ToLower();
            ArrayList list = new ArrayList();

            if (text[0] == 'j')
            {
                list.Add('i');
            }
            else
            {
                list.Add(text[0]);
            }

            for (int c = 1; c < text.Length; c++)
            {
                if (text[c] == ' ' || text[c] == ',' || text[c] == '.' || text[c] == '?' || text[c] == '!' || text[c] == ':' || text[c] == ';' || text[c] == '*' || text[c] == '(' || text[c] == ')' || text[c] == '"' || text[c] == '\n')
                {
                }

                else if (text[c] == 'j')
                {
                    list.Add('i');
                }
                else
                {
                    list.Add(text[c]);
                }
            }

            for (int c = 1; c < list.Count; c++)
            {
                if (list[c - 1].ToString() == list[c].ToString())
                {
                    list.Insert(c, 'x');
                }
            }
            if ((list.Count - 1) % 2 == 0)
            {
                list.Add('x');
            }


            String plaintext = string.Join("", list.ToArray());
            //  Console.WriteLine("Plaintext: " + plaintext);

            List <Plain> listPlains = new List <Plain>();

            for (int c = 1; c < plaintext.Length; c++)
            {
                if (c % 2 == 1)
                {
                    Plain plain = new Plain();

                    plain.setval1(plaintext[c - 1]);
                    plain.setval2(plaintext[c]);

                    listPlains.Add(plain);
                }
            }

            List <Plain> listEncrypted = new List <Plain>();

            foreach (Plain p in listPlains)
            {
                p.findCoordinates(cipher);
                if (p.getx1() == p.getx2())  //ten sam wiersz
                {
                    if (p.gety1() == 4)
                    {
                        p.sety2(p.gety2() + 1);
                        p.sety1(0);
                    }
                    else if (p.gety2() == 4)
                    {
                        p.sety2(0);
                        p.sety1(p.gety2() + 1);
                    }
                    else
                    {
                        p.sety1(p.gety1() + 1);
                        p.sety2(p.gety2() + 1);
                    }
                }
                else if (p.gety1() == p.gety2())  //ta sama kolumna
                {
                    if (p.getx2() == 4)
                    {
                        p.setx2(0);
                        p.setx1(p.getx1() + 1);
                    }
                    else if (p.getx1() == 4)
                    {
                        p.setx2(p.getx2() + 1);
                        p.setx1(0);
                    }
                    else
                    {
                        p.setx1(p.getx1() + 1);
                        p.setx2(p.getx2() + 1);
                    }
                }
                else                                    ///reszta
                {
                    int buf = p.gety1();
                    p.sety1(p.gety2());
                    p.sety2(buf);
                }

                p.findCipherLetters(cipher);

                listEncrypted.Add(p);
            }

            String encryptedString = null;

            foreach (Plain p in listEncrypted)
            {
                encryptedString = encryptedString + string.Join("", p.getval1().ToString()) + string.Join("", p.getval2().ToString());
            }
            return(encryptedString);
        }