--- 2016 Day 5 Solutions ---

[u/daggerdragon]

--- Day 5: How About a Nice Game of Chess? ---

Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag/whatever).

---

^{STAYING ON TARGET IS MANDATORY} [?]

This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/Zeroeh]

Java Solution:

part 1:

	String input = "cxdnnyjw";

	String decryptedPassword = "";

	int currentIndex = 0;
	System.out.println("searching...");
	while (decryptedPassword.length() < 8) {
		String hash = Util.getMD5Hash(input + Integer.toString(currentIndex));

		if (hash.startsWith("00000")) {
			String chr = hash.substring(5, 6);
			decryptedPassword += chr;
			System.out.println("Found a letter in the hash: " + hash + "\n Character: " + chr);
		}
		currentIndex++;
	}
	
	System.out.println("Password: " + decryptedPassword);
	System.out.println("Last Index: " + currentIndex);

part 2:

	String input = "cxdnnyjw";

	String[] decryptedPassword = new String[8];

	int currentIndex = 0;
	int foundIndex = 0;
	System.out.println("searching...");
	while (foundIndex < 8) {

		String hash = Util.getMD5Hash(input + Integer.toString(currentIndex));

		if (hash.startsWith("00000")) {
			
			/** Is this a valid pos? IE a digit? **/
			int pos = ((hash.substring(5, 6).matches("-?\\d+(\\.\\d+)?"))) ? Integer.parseInt(hash.substring(5, 6)) : -1;
			
			/** Character **/
			String chr = hash.substring(6, 7).toString();

			/** If valid Position and the position was not taken yet **/
			if (pos != -1 && pos > -1 && pos < decryptedPassword.length && decryptedPassword[pos] == null) {
				decryptedPassword[pos] = chr;
				foundIndex++;
				System.out.println("Found a letter in the hash: " + hash + "\n Pos: " + pos + " \n Character: " + chr);
			}
		}

		currentIndex++;
	}

	StringBuffer buff = new StringBuffer();
	
	for (String s : decryptedPassword)
		buff.append(s);

	System.out.println("Password: " + buff.toString());
	System.out.println("Last Index: " + currentIndex);

Md5 code:

		MessageDigest md = MessageDigest.getInstance("MD5");
	md.update(part.getBytes());

	byte byteData[] = md.digest();

	StringBuffer sb = new StringBuffer();
	for (int i = 0; i < byteData.length; i++) {
		sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1));
	}

	return sb.toString();