com.google.common.hash.MacHashFunction Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of wildfly-client-all

This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

There is a newer version: 34.0.0.Final

Show newest version

/*
 * Copyright (C) 2015 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.hash;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

import com.google.errorprone.annotations.Immutable;
import java.nio.ByteBuffer;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Mac;

/**
 * {@link HashFunction} adapter for {@link Mac} instances.
 *
 * @author Kurt Alfred Kluever
 */
@Immutable
@ElementTypesAreNonnullByDefault
final class MacHashFunction extends AbstractHashFunction {

  @SuppressWarnings("Immutable") // cloned before each use
  private final Mac prototype;

  @SuppressWarnings("Immutable") // keys are immutable, but not provably so
  private final Key key;

  private final String toString;
  private final int bits;
  private final boolean supportsClone;

  MacHashFunction(String algorithmName, Key key, String toString) {
    this.prototype = getMac(algorithmName, key);
    this.key = checkNotNull(key);
    this.toString = checkNotNull(toString);
    this.bits = prototype.getMacLength() * Byte.SIZE;
    this.supportsClone = supportsClone(prototype);
  }

  @Override
  public int bits() {
    return bits;
  }

  private static boolean supportsClone(Mac mac) {
    try {
      Object unused = mac.clone();
      return true;
    } catch (CloneNotSupportedException e) {
      return false;
    }
  }

  private static Mac getMac(String algorithmName, Key key) {
    try {
      Mac mac = Mac.getInstance(algorithmName);
      mac.init(key);
      return mac;
    } catch (NoSuchAlgorithmException e) {
      throw new IllegalStateException(e);
    } catch (InvalidKeyException e) {
      throw new IllegalArgumentException(e);
    }
  }

  @Override
  public Hasher newHasher() {
    if (supportsClone) {
      try {
        return new MacHasher((Mac) prototype.clone());
      } catch (CloneNotSupportedException e) {
        // falls through
      }
    }
    return new MacHasher(getMac(prototype.getAlgorithm(), key));
  }

  @Override
  public String toString() {
    return toString;
  }

  /** Hasher that updates a {@link Mac} (message authentication code). */
  private static final class MacHasher extends AbstractByteHasher {
    private final Mac mac;
    private boolean done;

    private MacHasher(Mac mac) {
      this.mac = mac;
    }

    @Override
    protected void update(byte b) {
      checkNotDone();
      mac.update(b);
    }

    @Override
    protected void update(byte[] b) {
      checkNotDone();
      mac.update(b);
    }

    @Override
    protected void update(byte[] b, int off, int len) {
      checkNotDone();
      mac.update(b, off, len);
    }

    @Override
    protected void update(ByteBuffer bytes) {
      checkNotDone();
      checkNotNull(bytes);
      mac.update(bytes);
    }

    private void checkNotDone() {
      checkState(!done, "Cannot re-use a Hasher after calling hash() on it");
    }

    @Override
    public HashCode hash() {
      checkNotDone();
      done = true;
      return HashCode.fromBytesNoCopy(mac.doFinal());
    }
  }
}