Thread: Identifying Hashes Efficiently?

Hello,

Before continuing a task that someone suggested for a mini-project, do you believe there is a more accurate way to identify hashes? Currently, I am using regex + length of hash to give the user possible hashes.

Identifier class:

package votek;
/*Author: Votek/Karil Votek
 * Purpose: Class is used to run checks on possible hashes that the user has entered. 
 */
public class Identifier {
 
	//Hash entered by user is stored here
	private String hash;
	//String that will contain all possible hashes to share with user
	private String results = "Possible Hashes: ";
	//Method that runs the other hash methods checks and prints out the results.
	public void runHashCheck(String hash) {
		//setting Identifier's private instance 'hash' to the String given by user
		this.hash = hash;
		//Methods for each hash
		checkMD2();
		checkMD5();
		checkSHA1();
		//If the results variable did not change, tells user nothing was found. Otherwise, shares possible hashes.
		if(results == "Possible Hashes: ") {
			System.out.println("No possible hashes were found.");
		} else {
			System.out.println(results);
			results = "Possible Hashes: ";
		}
	}
	//Method to check for MD2 hash
	private void checkMD2() { 
		boolean isMD2 = hash.matches("[0-fA-F0-9]{32}");
		if(isMD2) {
			results += "MD2 ";
		}
	}
	//Method to check for MD5 hash
	private void checkMD5() {
		boolean isMD5 = hash.matches("[0-fA-F0-9]{32}");
		if(isMD5) {
			results += "MD5 ";
		}
	}
	//Method to check for SHA1 hash
	private void checkSHA1() {
		boolean isSHA1 = hash.matches("[0-fA-F0-9]{40}");
		if(isSHA1) {
			results+= "SHA1 ";
		}
	}
 
	//More hash check methods will follow
 
}// end of Identifier class

HashIdentifier Class (main):

/*Author: Votek/Karil Votek
 * Program: User inserts a hash and methods are ran to determine possible hashes the hash may be.
 */
package votek;
 
import java.util.Scanner;
 
public class HashIdentifier {
 
	public static void main(String[] args) {
		//Creating & initializing an object for the Identifier class & Scanner class
		Identifier identifier = new Identifier();
		Scanner user = new Scanner(System.in);
		//Used to stop the loop
		char quit = 'n';
 
		//Continue loop of user inputting hashes/checking hashes
		while(Character.toLowerCase(quit) != 'q') {
			System.out.print("Please enter the hash you would like to check: ");
			identifier.runHashCheck(user.nextLine());
 
			System.out.println("Enter 'q' if you would like to quit the program. Otherwise, enter any other character: ");
			quit = user.nextLine().charAt(0);
		}
 
		user.close();
 
	}
 
} //end of HashIdentifier class

Originally Posted by Votek

do you believe there is a more accurate way to identify hashes

Nope. Hashes are one way finger prints. You can check the length and say it is possibly an MD5 hash but that's about it.

As for your actual code I would refactor those methods to accept the hash as a parameter and return a boolean.

public static boolean isPossiblyAnMD5(String hash) {
    if (hash.matches("[0-fA-F0-9]{32}")) {
        return true;
    }
    return false;
}

This will allow you to write unit tests and confirm it works for known MD5's.

Also, while I am here:

if(results == "Possible Hashes: ")

You need to use .equals() for string equality.

Originally Posted by ChristopherLowe

Nope. Hashes are one way finger prints. You can check the length and say it is possibly an MD5 hash but that's about it.

As for your actual code I would refactor those methods to accept the hash as a parameter and return a boolean.

public static boolean isPossiblyAnMD5(String hash) {
    if (hash.matches("[0-fA-F0-9]{32}")) {
        return true;
    }
    return false;
}

This will allow you to write unit tests and confirm it works for known MD5's.

Also, while I am here:

if(results == "Possible Hashes: ")

You need to use .equals() for string equality.

Thank you for the advice. After testing, is it okay to revert to the original code?

(Completed project but went back and did suggestion/it worked with MD5's)