Generates random output usable for design purposes. DO NOT USE FOR CRYPTO! YOU HAVE BEEN WARNED!

RandomOutput.java

/*
 * Copyright (c) 2015 Luis Hartmann
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.glasfrost.labs.randomoutput;

import static java.lang.Math.abs;
import java.util.Date;
import java.util.Random;

/**
 *
 * @author Luis
 */
public class RandomOutput {

    public static final String CHARS_BIN = "01";
    public static final String CHARS_OCT = "01234567";
    public static final String CHARS_DEC = "0123456789";
    public static final String CHARS_HEX = "123456789abcdef";
    public static final String CHARS_ALNUM = "0123456789"
            + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            + "abcdefghijklmnopqrstuvwxyz";
    
    public static final long DEFAULT_AMOUNT = 512;
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        
        if(args.length<1 || args.length>3){
            usage();
            System.exit(0);
        }
        
        long amount = DEFAULT_AMOUNT;
        Random rand = new Random();
        rand.setSeed(new Date().getTime());
        boolean debug = false;
        
        if(args.length>1){
            amount = Long.parseLong(args[1]);
        }
        
        if(args.length==3 && args[2].equals("debug")){
            debug = true;
        }
        
        err("main: amount: " + amount, debug);
        
        switch(args[0]){
            case "bin":
                generate(CHARS_BIN, rand, amount, debug);
                break;
            case "oct":
                generate(CHARS_OCT, rand, amount, debug);
                break;
            case "dec":
                generate(CHARS_DEC, rand, amount, debug);
                break;
            case "hex":
                generate(CHARS_HEX, rand, amount, debug);
                break;
            case "alnum":
                generate(CHARS_ALNUM, rand, amount, debug);
                break;
        }
        
        err("main: amount: " + amount, debug);
        
    }
    
    public static void generate(String charlist, Random rand, long amount, boolean debug){
        char[] chars = charlist.toCharArray();
        err("generate: charlist.length(): " + charlist.length(), debug);
        for(long count=0; count<amount; count++){
            int charnum = charlist.length();
            int pick = (abs(rand.nextInt()) % charnum);
            err("generate: pick: " + pick, debug);
            System.out.print(chars[pick]);
        }
        System.out.println();
    }
    
    public static void err(String msg, boolean debug){
        if(debug){
            System.err.println(msg);
        }
    }
    
    public static void usage(){
        System.err.println("RandomOutput");
        System.err.println("by Luis Hartmann 2015");
        System.err.println("");
        System.err.println("usage: RandomOutput <mode> [<amount>]");
        System.err.println("");
        System.err.println("     <mode> can be one of the following:");
        System.err.println("          bin");
        System.err.println("               Outputs binary chars");
        System.err.println("               0-1");
        System.err.println("");
        System.err.println("          oct");
        System.err.println("               Outputs octal chars");
        System.err.println("               0-7");
        System.err.println("");
        System.err.println("          dec");
        System.err.println("               Outputs decimal chars");
        System.err.println("               0-9");
        System.err.println("");
        System.err.println("          hex");
        System.err.println("               Outputs hexadecimal chars");
        System.err.println("               0-9 a-f");
        System.err.println("");
        System.err.println("          alnum");
        System.err.println("               Outputs alphanumerical chars");
        System.err.println("               0-9 a-z A-Z");
        System.err.println("");
        System.err.println("     <amount> is optional and defaults to "
                + DEFAULT_AMOUNT + ".");
        System.err.println("          It determines how many chars will be "
                + "generated.");
        System.err.println("");
        System.err.println("   WARNING:");
        System.err.println("   DO NOT RELY ON THE RANDOMNESS OF THE OUTPUT!");
        System.err.println("   THE CHARS ARE NOT INTENDED FOR CRYPTOGRAPHICAL "
                + "PURPOSES!");
        System.err.println("   USE AT OWN RISK!");
    }
    
}