Encrypt and Decrypt

Encrypt and Decrypt

Assign Value method

Encrypt button Event

String plainText = txtDec.getText();

     

        CaesarCrypt cc = new CaesarCrypt();

        String cipherText = cc.encrypt(plainText);

        lblEnc.setText(cipherText);

Decrypt button Event

String cipherText = txtEnc.getText();

       

        CaesarCrypt cc = new CaesarCrypt();

        String plainText = cc.decrypt(cipherText);

        lblDec.setText(plainText);

CaesarCrypt  Class code

public class CaesarCrypt {

   private final String chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890+-";

  

  

   public String encrypt(String plainText)

   {

       

         String cipherText="";

               

         for(int i=0; i < plainText.length(); i++)

         {

          

            if (plainText.charAt(i) == 'a')

            {

               cipherText += "1";

            }

            if (plainText.charAt(i) == 'b')

            {

               cipherText += "2";

            }

            if (plainText.charAt(i) == 'c')

            {

               cipherText += "3";

            }

            if (plainText.charAt(i) == 'd')

            {

               cipherText += "4";

            }

         }

         return cipherText;

   }

  

   public String decrypt(String cipherText)

   {

      

         String plainText="";    

        

         for(int i=0;i<cipherText.length();i++)

         {

         

            if (cipherText.charAt(i) == '1')

            {

               plainText += "a";

            }

            if (cipherText.charAt(i) == '2')

            {

               plainText += "b";

            }

            if (cipherText.charAt(i) == '3')

            {

               plainText += "c";

            }

            if (cipherText.charAt(i) == '4')

            {

               plainText += "d";

            }

         }

        

         return plainText;

   }

}

Shift Key method

Encrypt button Event

String plainText = txtDec.getText();

        int shiftKey = Integer.parseInt(txtShift.getText());

        caseaeCryptShift cc = new caseaeCryptShift();

        String cipherText = cc.encrypt(plainText, shiftKey);

        lblEnc.setText(cipherText);

Decrypt button Event

  String cipherText = txtEnc.getText();

        int shiftKey = Integer.parseInt(txtShift.getText());

        caseaeCryptShift cc = new caseaeCryptShift();

        String plainText = cc.decrypt(cipherText, shiftKey);

        lblDec.setText(plainText);

caseaeCryptShift Class code

public class caseaeCryptShift {

    private final String chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890+-";

    public String encrypt(String plainText, int shiftKey) {

      

        String cipherText = "";

        int charPosition;

        int keyVal;

        char replaceVal;

        for (int i = 0; i < plainText.length(); i++) {

            charPosition = chars.indexOf(plainText.charAt(i));

            keyVal = (charPosition + shiftKey) % 64;

            replaceVal = this.chars.charAt(keyVal);

            cipherText += replaceVal;

        }

        return cipherText;

    }

    public String decrypt(String cipherText, int shiftKey) {

      

        String plainText = "";

        int charPosition;

        int keyVal;

        char replaceVal;

        for (int i = 0; i < cipherText.length(); i++) {

            charPosition = this.chars.indexOf(cipherText.charAt(i));

            keyVal = charPosition - shiftKey;

            if (keyVal < 0) {

                keyVal = this.chars.length() + keyVal;

            }

            replaceVal = this.chars.charAt(keyVal);

            plainText += replaceVal;

        }

        return plainText;

    }

}

C# decryptuin with constant

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ConsoleApplication2

{

    class Program

    {

        static void Main(string[] args)

        {

            //Int64 id = Encrypt("abacus");

            string word = Dencrypt(334160560256);

            System.Console.WriteLine(word);

            System.Console.ReadLine();

        }

        private static Int64 Encrypt(string p)

        {

            Int64 c = 31;

            for (int i = 0; i < p.Length; i++)

            {

                c = c * 47 + (byte)p[i] % 97;

            }

            return c;

        }

        private static string Dencrypt(Int64 id)

        {

            string word = "";

            while (id > 31)

            {          

                byte c= (byte) (id % 47 + 97) ; // remove the multiplied value and extract the character

                char ch= Convert.ToChar(c); // get the charactor

                word = ch + word; // create the word

                id = id / 47;

               

            }

            return word;

        }

    }

}

/*

The following Python function encrypts plain text to

cipher text. For example given the text 'abacus' the function returns a

the cypher text 334160560256. Your task is to reverse engineer the

algorithm and find the source text which results in the cypher text

15731535468486 in a language of your choosing. Remember to comment the

code with your reasoning.

def encrypt (p):

    h = 31

    for i in range(0, len(p)):

        h = h * 47 + ord(p[i]) % 97

    return h

*/