Question

Create a Caesar Cipher in Java.

Should be able to support full ascii table (0 to infinity) with all symbols, characters, etc.

Using the Strings provided below, create an encryption and decryption method:

String basicText = "TOX!QL<];`\z6 L"n2=qafDkdp*a'S d 'SkQLq~+Ct*{8Y"4 ZnMxS.9e..&%9"

String password = "password1"

Answer 1

The java code for caesar cipher is given below

******************************Caesar.java**********************************

public class Caesar {
   //method for encrypting
   public static String createCipher(String p,int shift){
      
               //create a buffer string where we can append the
       //encrypted characters one by one
StringBuffer r= new StringBuffer();

        for (int j=0; j<p.length(); j++)
        {
                //The upper limit range of ASCII is 256
            // c= (value of character + shift)
            // and to keep it within range of ASCII LIMIT we use %256
                char cipherChar = (char)(((int)p.charAt(j) + shift) % 256);
                r.append(cipherChar);
           
        }
        //convert string buffer to final string cipher text
String ciphertext= r.toString();

return ciphertext;
  
      
   }
  
   //decryption is reverse of encryption
   public static String decrypt(String c,int shift){
      
      
StringBuffer r= new StringBuffer();

       for (int j=0; j<c.length(); j++)
       {
          
               char cipherChar = (char)(((int)c.charAt(j) - shift) % 256);
               r.append(cipherChar);
          
       }
String ciphertext= r.toString();
  
return ciphertext;

  
}

   public static void main(String[] args) {
       int shift=10;
       String s1= "TOX!QL<];`\\z6 L\"n2=qafDkdp*a'S d 'SkQLq~+Ct*{8Y\"4 ZnMxS.9e..&%9";
       String cipher1=createCipher(s1, shift);
       System.out.println("PlainText: "+s1);
       System.out.println("Cipher: "+cipher1);
       String decrypted1=decrypt(cipher1, shift);
       System.out.println("After decrypting: "+decrypted1);
      
       String s2="password1";
      
       String cipher2=createCipher(s2, shift);
       System.out.println("PlainText: "+s2);
       System.out.println("Cipher: "+cipher2);
       String decrypted2=decrypt(cipher2, shift);
       System.out.println("After decrypting: "+decrypted2);
}
}