revanced-patches/integrations/java/fi/vanced/libraries/youtube/ryd/Utils.java

package fi.vanced.libraries.youtube.ryd;

import android.util.Base64;
import android.util.Log;

import java.security.MessageDigest;

public class Utils {
    private static final String TAG = "VI - RYD - Utils";

    public static String solvePuzzle(String challenge, int difficulty) {
        byte[] decodedChallenge = Base64.decode(challenge, Base64.NO_WRAP);

        byte[] buffer = new byte[20];
        for (int i = 4; i < 20; i++) {
            buffer[i] = decodedChallenge[i - 4];
        }

        try {
            int maxCount = (int) (Math.pow(2, difficulty + 1) * 5);
            MessageDigest md = MessageDigest.getInstance("SHA-512");
            for (int i = 0; i < maxCount; i++) {
                buffer[0] = (byte)i;
                buffer[1] = (byte)(i >> 8);
                buffer[2] = (byte)(i >> 16);
                buffer[3] = (byte)(i >> 24);
                byte[] messageDigest = md.digest(buffer);

                if (countLeadingZeroes(messageDigest) >= difficulty) {
                    String encode = Base64.encodeToString(new byte[]{buffer[0], buffer[1], buffer[2], buffer[3]}, Base64.NO_WRAP);
                    return encode;
                }
            }
        }
        catch (Exception ex) {
            Log.e(TAG, "Failed to solve puzzle", ex);
        }

        return null;
    }

    static int countLeadingZeroes(byte[] uInt8View) {
        int zeroes = 0;
        int value = 0;
        for (int i = 0; i < uInt8View.length; i++) {
            value = uInt8View[i] & 0xFF;
            if (value == 0) {
                zeroes += 8;
            } else {
                int count = 1;
                if (value >>> 4 == 0) {
                    count += 4;
                    value <<= 4;
                }
                if (value >>> 6 == 0) {
                    count += 2;
                    value <<= 2;
                }
                zeroes += count - (value >>> 7);
                break;
            }
        }
        return zeroes;
    }
}