code: /*
   * Copyright (c) 2019 the Eclipse Milo Authors
   *
   * This program and the accompanying materials are made
   * available under the terms of the Eclipse Public License 2.0
   * which is available at https://www.eclipse.org/legal/epl-2.0/
   *
   * SPDX-License-Identifier: EPL-2.0
   */
  
  package org.eclipse.milo.opcua.stack.core.util;
  
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  
  import org.eclipse.milo.opcua.stack.core.StatusCodes;
  import org.eclipse.milo.opcua.stack.core.UaRuntimeException;
  
  public class DigestUtil {
  
      private static final ThreadLocal<MessageDigest> sha1Digest = new ThreadLocal<>();
  
      /**
       * Compute the SHA1 digest for a given input.
       *
       * @param input the input to compute the digest for.
       * @return the SHA1 digest of {@code input}.
       */
      public static byte[] sha1(byte[] input) {
          MessageDigest messageDigest = sha1Digest.get();
  
          if (messageDigest == null) {
              try {
                  messageDigest = MessageDigest.getInstance("SHA1");
                  sha1Digest.set(messageDigest);
              } catch (NoSuchAlgorithmException e) {
                  throw new UaRuntimeException(StatusCodes.Bad_InternalError, e);
              }
          }
  
          return messageDigest.digest(input);
      }
  
  }
  