gcc/libjava/classpath/gnu/javax/crypto/mac/BaseMac.java

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

This file is a part of GNU Classpath.

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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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package gnu.javax.crypto.mac;

import gnu.java.security.hash.IMessageDigest;

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

/**
 * <p>A base abstract class to facilitate <i>MAC</i> (Message Authentication
 * Code) implementations.</p>
 */
public abstract class BaseMac implements IMac
{

  // Constants and variables
  // -------------------------------------------------------------------------

  /** 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;

  /** The authentication key for this instance. */
  //   protected transient byte[] K;
  // Constructor(s)
  // -------------------------------------------------------------------------
  /**
   * <p>Trivial constructor for use by concrete subclasses.</p>
   *
   * @param name the canonical name of this instance.
   */
  protected BaseMac(String name)
  {
    super();

    this.name = name;
  }

  /**
   * <p>Trivial constructor for use by concrete subclasses.</p>
   *
   * @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;
  }

  // Class methods
  // -------------------------------------------------------------------------

  // Instance methods
  // -------------------------------------------------------------------------

  // gnu.crypto.mac.IMac interface implementation ----------------------------

  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;
  }

  // methods to be implemented by concrete subclasses ------------------------

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

  public abstract byte[] digest();

  public abstract boolean selfTest();
}