cryptoseals/backend/src/main/java/com/crypto/Caesar.java

package com.crypto;
public class Caesar {
    
    public static String encode(String plaintext, int key){
        String alphabet = "abcdefghijklmnopqrstuvwxyz";
        char encoded[] = plaintext.toCharArray();

        for(int i = 0; i < plaintext.length(); i++){
            if (alphabet.indexOf(encoded[i]) == -1) continue;
            encoded[i] = alphabet.charAt((alphabet.indexOf(encoded[i]) + key) % 26);
        }
        return String.valueOf(encoded);
    }

    public static String[] decode(String ciphertext){
        String alphabet = "abcdefghijklmnopqrstuvwxyz";
        char encoded[] = ciphertext.strip().toCharArray();

        char decoded[] = new char[ciphertext.length()];
        String bruteforce[] = new String[26];

        for(int key = 0; key < alphabet.length(); key++){

            for(int i = 0; i < ciphertext.length(); i++){
                if (alphabet.indexOf(encoded[i]) == -1) {
                    decoded[i] = encoded[i];
                    continue;
                }
                char current = encoded[i];
                int pos = alphabet.indexOf(current);
                if(pos != -1) {
                    int newpos = (pos + key) % 26;
                    decoded[i] = alphabet.charAt(newpos);
                } else
                    decoded[i] = current;
            }
            bruteforce[key] = String.valueOf(decoded);
        }
        return bruteforce;

    }
}