Caesar Decryption Algorithm

Caesar Decryption.java

public class NotePassing {
    public static String decipher (String codedMessage, int key){
        char[] charArray = new char[codedMessage.length()];
        int[] intArray = new int[codedMessage.length()+1];
        for (int r = 0; r < codedMessage.length(); r++){

            boolean isUCase = (codedMessage.charAt(r)>=65) && (codedMessage.charAt(r)<=90);
            boolean isLCase = (codedMessage.charAt(r)>=97) && (codedMessage.charAt(r)<=122);
            int changedAsci = ((int)codedMessage.charAt(r)) + key;
            if (isUCase) {
                intArray[r] = (changedAsci > 90) ? 64 + (changedAsci - 90) : changedAsci;
            }
            else if (isLCase){
                intArray[r] = (changedAsci > 122) ?  96 + (changedAsci - 122) : changedAsci;
            }
            else{
                intArray[r] = changedAsci - key;
            }
            charArray[r] = (char) intArray[r];
        }
        String decodedString = new String(charArray);         //passing char array object to string
        return decodedString;
        }
}

Caesar Decryption

Objective

This Algorithm converts a text encrypted via Caesar back to plain English text.

Methodology

1. Takes in stream of input and probable key
2. Each letter is checked for case
3. Based on case, shifts the letters by the case