BrokenDigestTest.java

package whatever;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.util.Random;

import com.google.common.base.Throwables;
import com.google.common.io.BaseEncoding;

public class BrokenDigestTest {
	private static final String VALID_CHARACTERS = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM1234567890_";
	public static void main(String[] args) {
		char[] arr = new char[16];
		Random rand = new Random(System.currentTimeMillis());
		System.out.println("Hashing 2000 random strings...");
		int fails = 0;
		for (int j = 0; j < 2000; j++) {
			for (int i = 0; i < arr.length; i++) {
				arr[i] = VALID_CHARACTERS.charAt(rand.nextInt(VALID_CHARACTERS.length()));
			}
			String str = new String(arr);
			System.out.print("Hashing "+str+"... ");
			String vanilla = hashVanilla(str);
			String custom = ServerID.javaHexDigest(str);
			String proper = hashProper(str);
			if (vanilla.equals(custom)) {
				System.out.println("OK");
			} else {
				fails++;
				System.out.println("FAIL");
				System.out.println("   Vanilla: "+vanilla);
				System.out.println("  ServerID: "+custom);
				System.out.println("  Standard: "+proper);
			}
		}
		System.out.println("Done. "+fails+"/2000 failed ("+(int)((fails/2000f)*100)+"% failure rate)");
	}
	private static String hashVanilla(String str) {
		MessageDigest md = null;
		try {
			md = MessageDigest.getInstance("SHA-1");
			md.reset();
			md.update(str.getBytes("UTF-8"));
		} catch (Exception e) {
			throw Throwables.propagate(e);
		}
		byte[] hash = md.digest();
		return new BigInteger(hash).toString(16);
	}
	
	private static String hashProper(String str) {
		MessageDigest md = null;
		try {
			md = MessageDigest.getInstance("SHA-1");
			md.reset();
			md.update(str.getBytes("UTF-8"));
		} catch (Exception e) {
			throw Throwables.propagate(e);
		}
		byte[] hash = md.digest();
		return BaseEncoding.base16().lowerCase().encode(hash);
	}
}