transposition

/* 
 * Example input:
 * attackpostponeduntiltwoam
 *	4312567
*/

import java.util.*;
public class transpoCipher {
	
	public static void main(String[] args) { 
		Scanner reader = new Scanner(System.in);
		//use to fill empty spots in last row
		String alphaL = "abcdefghijklmnopqrstuvwxyz";
		List<String> alpha = new ArrayList<String>();
		alpha = Arrays.asList(alphaL);

		//get message
		System.out.println("Enter the message: ");
		String str = reader.nextLine();
		//str.replaceAll("\\s","");

		//get key
		ArrayList<Integer> key = new ArrayList<Integer>(7);
		System.out.println("Enter the key: ");
		char[] tempK = reader.next().toCharArray();
		for(int t : tempK){
			key.add(Character.getNumericValue(t));
		}		

		//print out the key
		System.out.print("the key is: ");
		for(int x : key){
			System.out.print(x + " ");
		}
		System.out.println();

		//if not enough letters to fill last row, add in alphabet letters
		int numRows = str.length() / 7;
		if(str.length() % 7 > 0){
			numRows++;
			for(int i = str.length() % 7; i < 7; i++){
				str += "x";
			}
		}

		//create 2D array to store values from message into rows and columns
		//then print it out
		char [][] block = new char[numRows][7];
		System.out.println("plaintext:");
		int access = 0;
		for(int c = 0; c < numRows; c++){
			for(int r = 0; r < 7; r++){
				block [c][r] = str.charAt(access);
				System.out.print(block[c][r] + " ");
				access++;
			}
			System.out.println();
		}

		//go through the 2D array of plaintext to output the columns by order
		//of the key
		System.out.print("ciphertext: ");
		String ciphertext = "";
		for(int i = 0; i < key.size(); i++){
			int column = key.indexOf(i+1);
			
			for(int cs = 0; cs < numRows; cs++){
				for(int rs = 0; rs < 7; rs++){
					
					//if at the right index, print out char
					if(rs == column){
						ciphertext += (block[cs][rs]);
					}
					
				}
			}
		}
		System.out.println(ciphertext);
		//now time to decipher: given the key and the ciphertext
		
		int counter = 0;
		String decipher = "";
		ArrayList<ArrayList<String>> tempR = new ArrayList<ArrayList<String>>();

		while(counter < ciphertext.length()){
			ArrayList<String> temp = new ArrayList<String>();
			for(int i = 0; i < 4; i++){
				temp.add(Character.toString(ciphertext.charAt(counter)));
				counter++;
			}
			tempR.add(temp);
		}
			
		for(int i = 0; i < key.size(); i++){
			int patt = key.indexOf(i+1);
			ArrayList<String> temp = tempR.get(i);
			tempR.set(i, tempR.get(patt));
			tempR.set(patt, temp);
			decipher += tempR.get(i);
		}
		System.out.print("decryption: " + str);
	}

}