package org.sentrysoftware.ipmi.core.coding.security;
   
   /*-
    * ╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲
    * IPMI Java Client
    * ჻჻჻჻჻჻
    * Copyright 2023 Verax Systems, Sentry Software
    * ჻჻჻჻჻჻
    * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as
   * published by the Free Software Foundation, either version 3 of the
   * License, or (at your option) any later version.
   *
   * This program 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 General Lesser Public License for more details.
   *
   * You should have received a copy of the GNU General Lesser Public
   * License along with this program.  If not, see
   * <http://www.gnu.org/licenses/lgpl-3.0.html>.
   * ╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱╲╱
   */
  
  import javax.crypto.Mac;
  import javax.crypto.spec.SecretKeySpec;
  import java.security.InvalidKeyException;
  import java.security.NoSuchAlgorithmException;
  
  /**
   * HMAC-SHA1-96 integrity algorithm.
   */
  public class IntegrityHmacSha1_96 extends IntegrityAlgorithm {
  
      public static final String ALGORITHM_NAME = "HmacSHA1";
      private Mac mac;
  
      private static final byte[] CONST1 = new byte[] { 1, 1, 1, 1,
              1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 };
  
      /**
       * Initiates HMAC-SHA1-96 integrity algorithm.
       *
       * @throws NoSuchAlgorithmException
       *             - when initiation of the algorithm fails
       */
      public IntegrityHmacSha1_96() throws NoSuchAlgorithmException {
          mac = Mac.getInstance(ALGORITHM_NAME);
      }
  
      @Override
      public void initialize(byte[] sik) throws InvalidKeyException {
          super.initialize(sik);
  
          SecretKeySpec k1 = new SecretKeySpec(sik, ALGORITHM_NAME);
  
          mac.init(k1);
  
          k1 = new SecretKeySpec(mac.doFinal(CONST1), ALGORITHM_NAME);
  
          mac.init(k1);
      }
  
      @Override
      public byte getCode() {
          return SecurityConstants.IA_HMAC_SHA1_96;
      }
  
      @Override
      public byte[] generateAuthCode(final byte[] base) {
          if (sik == null) {
              throw new NullPointerException("Algorithm not initialized.");
          }
  
          byte[] result = new byte[12];
          byte[] updatedBase;
  
          if(base[base.length - 2] == 0 /*there are no integrity pad bytes*/) {
              updatedBase = injectIntegrityPad(base,12);
          } else {
              updatedBase = base;
          }
  
          System.arraycopy(mac.doFinal(updatedBase), 0, result, 0, 12);
  
          return result;
      }
  
  }