/* BaseMac.java -- 
   Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc.

This file is a part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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General Public License for more details.

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USA

Linking this library statically or dynamically with other modules is
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permission to link this library with independent modules to produce an
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package gnu.javax.crypto.mac;

import gnu.java.security.hash.IMessageDigest;

import java.security.InvalidKeyException;
import java.util.Map;

/**
 * A base abstract class to facilitate <i>MAC</i> (Message Authentication Code)
 * implementations.
 */
public abstract class BaseMac
    implements IMac
{
  /** The canonical name prefix of the <i>MAC</i>. */
  protected String name;
  /** Reference to the underlying hash algorithm instance. */
  protected IMessageDigest underlyingHash;
  /** The length of the truncated output in bytes. */
  protected int truncatedSize;

  /**
   * Trivial constructor for use by concrete subclasses.
   * 
   * @param name the canonical name of this instance.
   */
  protected BaseMac(String name)
  {
    super();

    this.name = name;
  }

  /**
   * Trivial constructor for use by concrete subclasses.
   * 
   * @param name the canonical name of this instance.
   * @param underlyingHash the underlying message digest algorithm instance.
   */
  protected BaseMac(String name, IMessageDigest underlyingHash)
  {
    this(name);

    if (underlyingHash != null)
      truncatedSize = underlyingHash.hashSize();
    this.underlyingHash = underlyingHash;
  }

  public String name()
  {
    return name;
  }

  public int macSize()
  {
    return truncatedSize;
  }

  public void update(byte b)
  {
    underlyingHash.update(b);
  }

  public void update(byte[] b, int offset, int len)
  {
    underlyingHash.update(b, offset, len);
  }

  public void reset()
  {
    underlyingHash.reset();
  }

  public Object clone() throws CloneNotSupportedException
  {
    BaseMac result = (BaseMac) super.clone();
    if (this.underlyingHash != null)
      result.underlyingHash = (IMessageDigest) this.underlyingHash.clone();

    return result;
  }

  public abstract void init(Map attributes) throws InvalidKeyException,
      IllegalStateException;

  public abstract byte[] digest();

  public abstract boolean selfTest();
}