Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * The MIT License (MIT)
 * <p/>
 * Copyright (c) 2013-2014 Valentin Konovalov
 * <p/>
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * <p/>
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * <p/>
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Main {
    public static boolean verifyChecksum(byte[] bytesWithChecksumm) {
        try {
            if (bytesWithChecksumm == null || bytesWithChecksumm.length < 5) {
                return false;
            }
            MessageDigest digestSha = MessageDigest.getInstance("SHA-256");
            digestSha.update(bytesWithChecksumm, 0, bytesWithChecksumm.length - 4);
            byte[] first = digestSha.digest();
            byte[] calculatedDigest = digestSha.digest(first);
            boolean checksumValid = true;
            for (int i = 0; i < 4; i++) {
                if (calculatedDigest[i] != bytesWithChecksumm[bytesWithChecksumm.length - 4 + i]) {
                    checksumValid = false;
                }
            }
            return checksumValid;
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }
}