RosettaCodeData/Task/Parallel-brute-force/Java/parallel-brute-force-1.java

94 lines
3.8 KiB
Java

import javax.xml.bind.DatatypeConverter;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
* "Main Program" that does the parallel processing
*/
public class ParallelBruteForce {
public static void main(String[] args) throws NoSuchAlgorithmException {
//the hashes to be cracked
String[] hashes = {"1115dd800feaacefdf481f1f9070374a2a81e27880f187396db67958b207cbad",
"3a7bd3e2360a3d29eea436fcfb7e44c735d117c42d1c1835420b6b9942dd4f1b",
"74e1bb62f8dabb8125a58852b63bdf6eaef667cb56ac7f7cdba6d7305c50a22f"};
//An ExecutorService is a high-level parallel programming facility, that can execute a number of tasks
//the FixedThreadPool is an ExecutorService that uses a configurable number of parallel threads
ExecutorService executorService = Executors.newFixedThreadPool(3);
//Submit one Task per hash to the thread po
for (String hash : hashes) {
executorService.submit(new Forcer(hash));
}
//An ExecutorSerice must be shut down properly (this also causes the program to await termination of
// all pending tasks in the thread pool)
executorService.shutdown();
}
}
/**
* The Class that contains the actual brute-forcing task.
* <p>
* It implements the build-in Interface "Runnable", so it can be run on a Thread or a Thread-Execution-Facility
* (such as an ExecutorService).
*/
class Forcer implements Runnable {
private static final int LENGTH = 5;
//These will sore the hash to be cracked in both bytes (required for comparison) and String representation
// (required for output)
private final byte[] crackMe;
private final String crackMeString;
//The MessageDigest does the SHA-256 caclulation. Note that this may throw a NoSuchAlgorithmException when there
// is no SHA-256 implementation in the local standard libraries (but that algorithm is mandatory, so this code
// probably will never throw that Excpetion
private final MessageDigest digest = MessageDigest.getInstance("SHA-256");
public Forcer(String crackMe) throws NoSuchAlgorithmException {
this.crackMeString = crackMe;
this.crackMe = DatatypeConverter.parseHexBinary(crackMe);
}
@Override
public void run() {
String match = "";
//all loops use this array for their counters. This is very dirty and should never be done in production!
char[] chars = new char[LENGTH];
//used for short-stopping when a match is found - one could abuse the match-variable for this, but this is
// much clearer
boolean done = false;
for (chars[0] = 'a'; chars[0] <= 'z' && !done; chars[0]++) {
for (chars[1] = 'a'; chars[1] <= 'z' && !done; chars[1]++) {
for (chars[2] = 'a'; chars[2] <= 'z' && !done; chars[2]++) {
for (chars[3] = 'a'; chars[3] <= 'z' && !done; chars[3]++) {
for (chars[4] = 'a'; chars[4] <= 'z' && !done; chars[4]++) {
//the String creation is necessary to get the encoding right
String canidate = new String(chars);
//genenrate SHA-256 hash using Java's standard facilities
byte[] hash = digest.digest(canidate.getBytes());
if (Arrays.equals(hash, crackMe)) {
match = canidate;
done = true;
}
}
}
}
}
}
System.out.println(String.format("Hash %s has the following match : %s", crackMeString, match));
}
}