Programming Challange: Ceaser Cipher

[majorawsome]

Well, I have been learning Cryptology in my math class, and I have been trying to make a program that deciphers the Ceaser cipher I realized how this program has been a challange for me. I then thought, hey, why not make this the first Challange on the Forum? So now I am making a challange.

 

But first, what is the Ceaser cipher? It is when you take a string of characters and shift them left or right. So if you have a  string "abcd" and shift right 1, it will be "bcde". Also take a look at this link for a better explanation http://www.cs.trincoll.edu/~crypto/historical/caesar.html

 

Challange: Create a program that Deciphers and Ciphers a string of characters.

 

How to Answer: Attach a picture of the program and the code.

 

 

[MasterOfDisaster]

Here's my solution, written in pure C code.

 

I wrote this code assuming the messages only consist of spaces and lowercases. It works quite well, even if it does not check the input for accuracy - I intentionally skipped those parts so that you can concentrate on the main decoding/encoding logic:

#include <stdlib.h>#include <stdio.h>#include <string.h>int main(int argc, char **argv){    printf("Action: ");    char action[10];    fgets(action, 10, stdin);    char str[1000];    if(!strcmp(action, "encipher\n"))    {        printf("Enter string to encipher (max. 999 letters & only lowercases):\n");        fgets(str, 1000, stdin);        int shiftValue = 0;        printf("Enter shift value: ");        scanf("%d", &shiftValue);        if(shiftValue > 0)        {            for(int i = 0; str[i]; ++i)            {                if(str[i] == ' ' || str[i] == '\n')                    continue;                str[i] += shiftValue;                while(str[i] > 'z')                {                    str[i] = 'a' + (str[i] - 'z');                }            }        }        else if(shiftValue < 0)        {            for(int i = 0; str[i]; ++i)            {                if(str[i] == ' ' || str[i] == '\n')                    continue;                str[i] -= shiftValue;                while(str[i] < 'a')                {                    str[i] = 'z' - ('a' - str[i]);                }            }        }        printf("Enciphered message: \n%s", str);    }    else if(!strcmp(action, "decipher\n"))    {        printf("Enter string to decipher (max. 999 letters & only lowercases):\n");        fgets(str, 1000, stdin);        int shiftValue = 0;        printf("Enter shift value: ");        scanf("%d", &shiftValue);        if(shiftValue < 0)        {            for(int i = 0; str[i]; ++i)            {                if(str[i] == ' ' || str[i] == '\n')                    continue;                str[i] += shiftValue;                while(str[i] > 'z')                {                    str[i] = 'a' + (str[i] - 'z');                }            }        }        else if(shiftValue > 0)        {            for(int i = 0; str[i]; ++i)            {                if(str[i] == ' ' || str[i] == '\n')                    continue;                str[i] -= shiftValue;                while(str[i] < 'a')                {                    str[i] = 'z' - ('a' - str[i]);                }            }        }        printf("Enciphered message: \n%s", str);    }    else    {        printf("Invalid command!\n");        exit(-1);    }    return 0;}

I found this much more readable than a picture of the code. But here is a picture of the application running in the console: http://oi42.tinypic.com/2qsb1w9.jpg

[arkon]

choice = input("Choose an action:\r\n 1: Encipher\r\n 2: Decipher\r\n")while (choice != "1" and choice != "2"):    choice = input("Please choose a valid action:\r\n 1: Encipher\r\n\ 2: Decipher\r\n")if choice == '1':    string = input("\r\nEnter a string to encipher (lowercase):\r\n")else:    string = input("\r\nEnter a string to decipher (lowercase):\r\n")shift = int(input("\r\nEnter shift value: "))newstr = ''if choice == '1':    for char in string:        newstr += chr((ord(char) - ord('a') + shift)  % 26 + ord('a'))else:    for char in string:        newstr += chr((ord(char) - ord('a') - shift)  % 26 + ord('a'))print("\r\nMessage:\r\n" + newstr)

Written in Python 3, and a screenshot: http://i.imgur.com/ogZBUs1.png

 

[Darkfeign]

Man the difference in amount of code required between C and python becomes so apparent in the above two examples.

[Tigerbomb8]

Man the difference in amount of code required between C and python becomes so apparent in the above two examples.

Not really, the formatting in the C++ code added 30+ lines that was just  '{' and '}'. it could also be compacted to the same size as the python code

[Darkfeign]

Still not the same size as the python program.

[arkon]

Not really, the formatting in the C++ code added 30+ lines that was just  '{' and '}'. it could also be compacted to the same size as the python code

 

Could cut it down to about 90-95 lines by removing some of the useless brackets.

[majorawsome]

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Cryptology{    class Program    {        static void Main(string[] args)        {            Console.WriteLine("Hello, and welcome to an encryption/decryption program writtern in C# by Austin DeLauney");            Console.WriteLine("Enter 1 for encryption and 2 for decryption, and 3 for letter analysis");            int decision = Convert.ToInt32(Console.ReadLine());            switch (decision)            {                case 1:                    Console.WriteLine("Please enter the string to encode");                    string toEncode = Console.ReadLine();                    Encrypt e = new Encrypt(toEncode);                    break;                case 2:                    Console.WriteLine("Please enter the string to decode");                    string toDecode = Console.ReadLine();                    Decrypt d = new Decrypt(toDecode);                    break;                case 3:                    Console.WriteLine("Please enter the string to analyze");                    string toAnalyze = Console.ReadLine();                    Analyze a = new Analyze(toAnalyze);                    break;                default:                    Console.WriteLine("NOW RUNNING NOPE.EXE");                    for (int i = 0; i < 10000; i++)                        Console.WriteLine("NOPE");                    Console.Read();                    break;            }            Console.ReadLine();        }    }}

Program.cs

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Cryptology{    class Encrypt    {        String PlainText = null;        Char[] Alphabet = "abcdefghijklmnopqrstuvwxyz".ToCharArray();        public Encrypt(String toEncrypt)        {            PlainText = toEncrypt;            Console.WriteLine("Enter 1 for Ceaser, 2 for Vigenere");            int decision = Convert.ToInt32(Console.ReadLine());            switch (decision)            {                case 1:                    Console.WriteLine("GIMME DAT KEY BRUH");                    char charKey = Convert.ToChar(Console.ReadLine());                    Console.WriteLine(CeaserEncipher(charKey));                    break;                case 2:                    Console.WriteLine("GIMME DAT KEY BRUH");                    String stringKey = Console.ReadLine();                    Console.WriteLine(VigenereEncipher(stringKey));                    break;            }            Console.ReadLine();        }        public String CeaserEncipher(char key)        {            StringBuilder sB = new StringBuilder();            //Console.WriteLine((int)(key));            int shift = key - 97;            foreach (var character in PlainText)            {                int val = character - 97;                int remander = (val + shift);                if (remander > ('z' - 97)) //On Overflow                    remander -= 26;                else if (remander < ('a' - 97)) //On Underflow                    remander += 26;                //Console.WriteLine(remander);                sB.Append(Alphabet[remander]);            }            return sB.ToString();        }        public Char CeaserEncipher(char key, int index)        {            //Console.WriteLine((key));            int shift = key - 97;            int val = PlainText[index] - 97;            int remander = (val + shift);            if (remander > ('z' - 97)) //On Overflow                remander -= 26;            else if (remander < ('a' - 97)) //On Underflow                remander += 26;            //Console.WriteLine(remander);            return (Alphabet[remander]);        }        public String VigenereEncipher(String key)        {            StringBuilder sB = new StringBuilder();            key = key.ToLower();            Char[] keyChar = key.ToCharArray();            for (int i = 0; i < PlainText.Length; i++)            {                int remander = i % key.Length;                //Console.WriteLine(keyChar[remander]);                sB.Append(CeaserEncipher(keyChar[remander], i));            }            return sB.ToString();        }    }}

Encrypt.cs

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Cryptology{    class Decrypt    {        String CipherText = null;        Char[] CodeArray = null;        Char[] Alphabet = "abcdefghijklmnopqrstuvwxyz".ToCharArray();        public Decrypt (String s)        {            CipherText = s.ToLower();            CodeArray = CipherText.ToCharArray();            Console.WriteLine("Enter 1 for Brute Force Ceaser, 2 for Code Ceaser, 3 for Vigenere");            int decision = Convert.ToInt32(Console.ReadLine());            switch (decision)            {                case 1:                    CeaserDecipher();                    break;                case 2:                    Console.WriteLine("GIMME DAT KEY BRUH");                    char charKey = Convert.ToChar(Console.ReadLine());                    Console.WriteLine(CeaserDecipher(charKey));                    Console.ReadLine();                    break;                case 3:                    Console.WriteLine("GIMME DAT KEY BRUH");                    String stringKey = Console.ReadLine();                    VigenereDecipher(stringKey);                    break;            }        }        public void CeaserDecipher()        {            for (int i = 0; i < Alphabet.Length; i++)            {                Console.Write(Alphabet[Math.Abs(i)] + ": ");                foreach (var character in CipherText)                {                    int val = character - 97;                    int remander = (val - i);                    if (remander > ('z' - 97)) //On Overflow                        remander -= 26;                    else if (remander < ('a' - 97)) //On Underflow                        remander += 26;                    //Console.WriteLine(remander);                    Console.Write(Alphabet[remander]);                }                Console.WriteLine();            }            Console.Read();        }        public String CeaserDecipher(char key)        {            StringBuilder sB = new StringBuilder();            //Console.WriteLine((int)(key));            int shift = key - 97;            foreach (var character in CipherText)            {                int val = character - 97;                int remander = (val - shift);                if (remander > ('z' - 97)) //On Overflow                    remander -= 26;                else if (remander < ('a' - 97)) //On Underflow                    remander += 26;                //Console.WriteLine(remander);                sB.Append(Alphabet[remander]);            }            return sB.ToString();        }        public Char CeaserDecipher(char key, int index)        {            //Console.WriteLine((int)(key));            int shift = key - 97;            int val = CipherText[index] - 97;            int remander = (val - shift);            if (remander > ('z' - 97)) //On Overflow                remander -= 26;            else if (remander < ('a' - 97)) //On Underflow                remander += 26;            //Console.WriteLine(remander);            return (Alphabet[remander]);        }        public void VigenereDecipher(String key)        {            key = key.ToLower();            Char[] keyChar = key.ToCharArray();            for (int i = 0; i < keyChar.Length; i++)            {                keyChar[i] = (char)(keyChar[i]);                //Console.WriteLine(keyChar[i]);            }            for (int i = 0; i < CipherText.Length; i++)            {                int remander = i % key.Length;                //Console.WriteLine(keyChar[remander]);                Console.Write(CeaserDecipher(keyChar[remander], i));            }        }    }}

Decrypt.cs

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Cryptology{    class Analyze    {        String Text = null;        Char[] Alphabet = "abcdefghijklmnopqrstuvwxyz".ToCharArray();        int Jump = 0;         public Analyze(string toAnalyze)        {            Text = toAnalyze.ToLower();            Console.WriteLine("Enter the numbers to skip");            Jump = Convert.ToInt32(Console.ReadLine());            PrintLetterOccurence();            Console.ReadLine();        }        private int[] countLetters(int jump, int startingPos)        {            int[] count = new int[26];            for (int i = startingPos; i < Text.Length; i += jump)            {                count[Text[i] - 97]++;            }           /* for (int i = 0; i < count.Length; i++)            {                Console.Write(Alphabet[i] + " ");                Console.WriteLine(count[i]);            }*/            return count;        }        public int[] LetterOccurence()        {            int[] occurence = new int[26];            foreach (var character in Text)            {                int remander = (character - 97);                occurence[remander]++;            }            return occurence;        }        public void PrintLetterOccurence()        {            for (int i = 0; i < Jump; i++)            {                int[] occurence = countLetters(Jump, i);                for (int i2 = 0; i2 < Alphabet.Length; i2++)                {                    Console.Write(Alphabet[i2] + ": ");                    Console.WriteLine(occurence[i2]);                }                Console.WriteLine();            }        }    }}

and Analyze.cs

 

This code is in C#, and the program Decrypts and Encrypts Ceaser, brute forces Ceaser and encrypts, decrypts Vigenere (DIfferent type of Ciphering I learned). It also includes an analyze class that analyzes the amount of letters in the string (For vigenere decryption)

[arkon]

~ massive snip ~

 

Haha, NOPE.EXE

[fletch to 99]

 

SRC

import java.awt.Container;import java.awt.Dimension;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JOptionPane;import javax.swing.JTextField;import javax.swing.UIManager;import javax.swing.UnsupportedLookAndFeelException;/** * @date September 11 2012 * @purpose A very simple encryption based off of ROT13 * @author matthewlanglois11 *  */public class SimpleEncryption {    /**     * The main method which initlizes the program.     *      * @param args     *            Any arguments passed to the program.     * @throws UnsupportedLookAndFeelException     * @throws IllegalAccessException     * @throws InstantiationException     * @throws ClassNotFoundException     */    public static void main(final String[] args) throws ClassNotFoundException,            InstantiationException, IllegalAccessException,            UnsupportedLookAndFeelException {        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());        //create an instance of the gui and set it visible        new GUI().setVisible(true);    }    //Max/Mins unicodes for chars A-Z and a-z    private static final int min_lower = 97;    private static final int max_lower = 122;    private static final int min_upper = 65;    private static final int max_upper = 90;    /**     *      *      * @param string The string to encrypt     * @param shift The amount to shift 1-25     * @return The encrypted string     */    public static String encrypt(String string, int shift) {        String encrypted = "";        for (char c : string.toCharArray()) {            if (Character.isLetter©) {                int abyte = ((int) c) + shift;                if (Character.isUpperCase©) {                    if (abyte > max_upper) {//wrap around the alphabet                        abyte = abyte -1 - max_upper + min_upper;                    }                } else {                    if (abyte > max_lower) {//wrap around the alphabet                        abyte = abyte -1 - max_lower + min_lower;                    }                }                encrypted += String.valueOf((char) abyte);            } else {                encrypted += String.valueOf©;            }        }        return encrypted;    }     /**     *     *     * @param string The string to decrypt     * @param shift The shift amount     * @return The decrypted string     */    public static String decrypt(String string, int shift) {        String decrypted = "";        for (char c : string.toCharArray()) {            if (Character.isLetter©) {                int abyte = ((int) c) - shift;                if (Character.isUpperCase©) {                    if (abyte < min_upper) {//wrap around the alphabet                        abyte = abyte + max_upper - min_upper + 1;                    }                } else {                    if (abyte < min_lower) {//wrap around the alphabet                        abyte = abyte + max_lower - min_lower + 1;                    }                }                decrypted += String.valueOf((char) abyte);            } else {                decrypted += String.valueOf©;            }        }        return decrypted;    }}class GUI extends JFrame {    /**     * Checks if a string is a valid integer.     *      * @param message     *            The string to parse.     * @return True if the string is a valid number; otherwise false.     */    public static boolean canParse(String message) {        try {            Integer.parseInt(message);        } catch (Exception e) {            return false;        }        return true;    }    private static final long serialVersionUID = 2053636315187421222L;    public GUI() {        initComponents();    }    private void decryptActionPerformed(final ActionEvent e) {        int amount = 13; // ROT 13 reference        if (canParse(this.amount.getText())) {            amount = Integer.parseInt(this.amount.getText());            if (amount > 25 || amount < 1) {                JOptionPane.showMessageDialog(this,                        "The amount to shift must be between 1-25");                return;            }        }        text.setText(SimpleEncryption.decrypt(encryption.getText(), amount));    }    private void encryptActionPerformed(final ActionEvent e) {        int amount = 13; // ROT 13 reference        if (canParse(this.amount.getText())) {            amount = Integer.parseInt(this.amount.getText());            if (amount > 25 || amount < 1) {                JOptionPane.showMessageDialog(this,                        "The amount to shift must be between 1-25");                return;            }        }        encryption.setText(SimpleEncryption.encrypt(text.getText(), amount));    }    /**     * Set up and add all of the components to the frame.     */    private void initComponents() {        encrypt = new JButton();        decrypt = new JButton();        encryption = new JTextField();        text = new JTextField();        amount = new JTextField();        setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);        addWindowListener(new WindowAdapter() {            @Override            public void windowClosing(final WindowEvent e) {                System.exit(1);            }        });        setTitle("Simple Encryption Program by Matt");        final Container contentPane = getContentPane();        contentPane.setLayout(null);        this.setResizable(false);        decrypt.setText("Decrypt");        decrypt.addActionListener(new ActionListener() {            @Override            public void actionPerformed(final ActionEvent e) {                decryptActionPerformed(e);            }        });        contentPane.add(decrypt);        decrypt.setBounds(5, 105, 290, 20);        text.setText("Plain text...");        contentPane.add(text);        text.setBounds(5, 5, 290, 20);        amount.setText("ROT Amount...");        contentPane.add(amount);        amount.setBounds(5, 55, 290, 20);        encryption.setText("Encryption...");        contentPane.add(encryption);        encryption.setBounds(5, 30, 290, 20);        encrypt.setText("Encrypt");        contentPane.add(encrypt);        encrypt.setBounds(5, 80, 290, 20);        encrypt.addActionListener(new ActionListener() {            @Override            public void actionPerformed(final ActionEvent e) {                encryptActionPerformed(e);            }        });        contentPane.setPreferredSize(new Dimension(300, 130));        pack();    }    private JButton encrypt;    private JButton decrypt;    private JTextField text;    private JTextField encryption;    private JTextField amount;}

[Darren]

A break from walls of text... I'm assuming valid input, since I believe if you make a script for yourself, you know the syntax. In a professional environment I would have documentation for everything :P

import sysout = ''for letr in sys.argv[2]:        if sys.argv[1] is 'e':                out+=chr(ord(letr) + int(sys.argv[3]))        elif sys.argv[1] is 'd':                out+=chr(ord(letr) - int(sys.argv[3]))        else:                print 'Usage for script:\n[e:d] [string] [offset] where \ne = encrypt, d = decrypt \nString = String to pass through \noffset = integer offest of chars'                quit()print out

[arkon]

 

A break from walls of text... I'm assuming valid input, since I believe if you make a script for yourself, you know the syntax. In a professional environment I would have documentation for everything :P

import sysout = ''for letr in sys.argv[2]:        if sys.argv[1] is 'e':                out+=chr(ord(letr) + int(sys.argv[3]))        elif sys.argv[1] is 'd':                out+=chr(ord(letr) - int(sys.argv[3]))        else:                print 'Usage for script:\n[e:d] [string] [offset] where \ne = encrypt, d = decrypt \nString = String to pass through \noffset = integer offest of chars'                quit()print out

 

Is this Python 2?

[Darren]

Is this Python 2?

 

Yes, ran in python2.7.2. Shouldn't differ too much for basic stuff like this.