I'm working on a simple encryption program (for school). It is not currently "homework" just FYI, I'm just practicing the examples in the book. It uses a Caesar's Cipher method (an alphabetical shift).
I have not tested this code very much. If something is wrong with it I probably don't know about it. The problem is when this programs runs, it doesn't print the entire message. It prints the first word and then nothing. I just got a hunch in that perhaps it doesn't handle whitespace correctly though...
T0he code:
import java.util.*;
import Utility.Utility; //Import my utility class
public class Cipher {
char forDecrypting[] = new char [26]; //Standard reference alphabet for performing operations on
char forEncrypting[] = new char [26]; //reference alphabet for performing DEcryption
char shift = 0;
public Cipher ()
{
this(3); //Call argument constructor
this.shift = 3;
}
public Cipher (int shift) {
/*Initializes encoding alphabets using an argument specified shift*/
int c = 0;
for(int j = 0; j < 26; j++) {
this.forDecrypting[c] = (char) ((int) 'A' + (j + shift) % 26); //Store the regular alphabet for decrypting
this.forEncrypting[c] = (char) ((int) 'A' + (j - shift + 26 ) % 26); //Store the shifted alphabet for encrypting
c+=1;
}
}
public char transform (boolean encrypting, char ch, int msgLen) { //Changes the char in to its encrypted equivalent
int index = 0;
if(encrypting) { //If we want to encrypt the message
index = Utility.Clamp( ((int) ( ch - 'A')), 0, 25);
System.out.print(" index = " + ((char )index) + " " );
return forEncrypting[index]; //Return the encrypted char
} else {
index = Utility.Clamp( ((int) ( ch - 'A')), 0, 25);
System.out.print(" index = " + ((char )index) + " " );
return forDecrypting[index]; //Else return the decrypted char
}
}
public String encode (String plaintext) {
char [] message = plaintext.toUpperCase().toCharArray(); //Put the plaintext in to an array
char [] cipher = new char [message.length];
for(int p = 0; p <= message.length - 1; p++) { //Iterate through the message, replacing each letter with its corresponding encrypted char
cipher[p] = transform(true, message[p], message.length - 1);
}
return new String(cipher);
}
public String decode (String ciphertext) {
char [] cipher = ciphertext.toUpperCase().toCharArray(); //Put the plaintext in to an array
char [] plaintext = new char [cipher.length];
for(int p = 0; p <= cipher.length - 1; p++) { //Iterate through the message, replacing each letter with its corresponding encrypted char
plaintext[p] = transform(false, cipher[p], cipher.length - 1);
}
return new String(plaintext);
}
public static void main (String[] args) {
System.out.print("A = " +((int) 'A') + " Z = " + ((int)'Z') );
Cipher myCipher = new Cipher();
String ciphertext = new String(myCipher.encode(args[0]));
System.out.println(" Cipher is: " + ciphertext + " Message is: " + new String (myCipher.decode(ciphertext)) );
}
}
The Utility.Clamp function simply forces the value to a range. IE. If the range is from zero to 25, and we specify 100, we get back 25, or if it is -9 we get back zero. If the value is anywhere in the range then it just returns the input value.
Also these are my programs arguments:
"If you can read this then crap if not then good"
and sample output as of now:
"A = 65 Z = 90 index = index = index = index = Cipher is: FC Message is: IF "
