content: /*
   *  Copyright (C) 2010-2018,2020 Stichting Akvo (Akvo Foundation)
   *
   *  This file is part of Akvo FLOW.
   *
   *  Akvo FLOW is free software: you can redistribute it and modify it under the terms of
   *  the GNU Affero General Public License (AGPL) as published by the Free Software Foundation,
   *  either version 3 of the License or any later version.
   *
   *  Akvo FLOW is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
   *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   *  See the GNU Affero General Public License included below for more details.
   *
   *  The full license text can also be seen at <http://www.gnu.org/licenses/agpl.html>.
   */
  
  package com.gallatinsystems.common.util;
  
  import java.security.InvalidKeyException;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Base64;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  import javax.crypto.Mac;
  import javax.crypto.spec.SecretKeySpec;
  
  /**
   * utility for generating checksums and digests
   * 
   * @author Christopher Fagiani
   */
  public class MD5Util {
      private static final Logger log = Logger.getLogger(MD5Util.class.getName());
  
      public static byte[] md5(byte[] arr) {
          try {
              MessageDigest complete = MessageDigest.getInstance("MD5");
              complete.update(arr);
              return complete.digest();
          } catch (NoSuchAlgorithmException e) {
              log.log(Level.SEVERE, "Could not generate checksum", e);
          }
          return null;
      }
  
      /**
       * generates a checksum based on an MD5 message digest
       * 
       * @param arr
       * @return
       */
      public static String generateChecksum(byte[] arr) {
          byte[] digest = md5(arr);
          if (digest != null) {
              return toHex(digest);
          }
          return null;
      }
  
      public static String toHex(byte[] data) {
          StringBuilder builder = new StringBuilder();
          for (byte b : data) {
              builder.append(String.format("%02x", b));
          }
          return builder.toString();
      }
  
      public static String generateHMAC(String content, String privateKey) {
          Mac mac;
          try {
              mac = Mac.getInstance("HmacSHA1");
              SecretKeySpec secret = new SecretKeySpec(privateKey.getBytes(),
                      mac.getAlgorithm());
              mac.init(secret);
              byte[] digest = mac.doFinal(content.getBytes());
              return Base64.getEncoder().encodeToString(digest);
          } catch (NoSuchAlgorithmException e) {
              log.log(Level.SEVERE, e.getMessage(), e);
          } catch (InvalidKeyException e) {
              log.log(Level.SEVERE, e.getMessage(), e);
          }
          return null;
      }
  }
  