/*

 * Copyright 1998-2007 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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 Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.crypto.spec;

import java.security.spec.AlgorithmParameterSpec;

/**

 * This class specifies the parameters used with the

 * <a href="http://www.ietf.org/rfc/rfc2268.txt"><i>RC2</i></a>

 * algorithm.

 *

 * <p> The parameters consist of an effective key size and optionally

 * an 8-byte initialization vector (IV) (only in feedback mode).

 *

 * <p> This class can be used to initialize a <code>Cipher</code> object that

 * implements the <i>RC2</i> algorithm.

 *

 * @author Jan Luehe

 *

 * @since 1.4

 */

public class RC2ParameterSpec implements AlgorithmParameterSpec {

    private byte[] iv = null;

    private int effectiveKeyBits;

    /**

     * Constructs a parameter set for RC2 from the given effective key size

     * (in bits).

     *

     * @param effectiveKeyBits the effective key size in bits.

     */

    public RC2ParameterSpec(int effectiveKeyBits) {

        this.effectiveKeyBits = effectiveKeyBits;

    }

    /**

     * Constructs a parameter set for RC2 from the given effective key size

     * (in bits) and an 8-byte IV.

     *

     * <p> The bytes that constitute the IV are those between

     * <code>iv[0]</code> and <code>iv[7]</code> inclusive.

     *

     * @param effectiveKeyBits the effective key size in bits.

     * @param iv the buffer with the 8-byte IV. The first 8 bytes of

     * the buffer are copied to protect against subsequent modification.

     * @exception IllegalArgumentException if <code>iv</code> is null.

     */

    public RC2ParameterSpec(int effectiveKeyBits, byte[] iv) {

        this(effectiveKeyBits, iv, 0);

    }

    /**

     * Constructs a parameter set for RC2 from the given effective key size

     * (in bits) and IV.

     *

     * <p> The IV is taken from <code>iv</code>, starting at

     * <code>offset</code> inclusive.

     * The bytes that constitute the IV are those between

     * <code>iv[offset]</code> and <code>iv[offset+7]</code> inclusive.

     *

     * @param effectiveKeyBits the effective key size in bits.

     * @param iv the buffer with the IV. The first 8 bytes

     * of the buffer beginning at <code>offset</code> inclusive

     * are copied to protect against subsequent modification.

     * @param offset the offset in <code>iv</code> where the 8-byte IV

     * starts.

     * @exception IllegalArgumentException if <code>iv</code> is null.

     */

    public RC2ParameterSpec(int effectiveKeyBits, byte[] iv, int offset) {

        this.effectiveKeyBits = effectiveKeyBits;

        if (iv == null) throw new IllegalArgumentException("IV missing");

        int blockSize = 8;

        if (iv.length - offset < blockSize) {

            throw new IllegalArgumentException("IV too short");

        }

        this.iv = new byte[blockSize];

        System.arraycopy(iv, offset, this.iv, 0, blockSize);

    }

    /**

     * Returns the effective key size in bits.

     *

     * @return the effective key size in bits.

     */

    public int getEffectiveKeyBits() {

        return this.effectiveKeyBits;

    }

    /**

     * Returns the IV or null if this parameter set does not contain an IV.

     *

     * @return the IV or null if this parameter set does not contain an IV.

     * Returns a new array each time this method is called.

     */

    public byte[] getIV() {

        return (iv == null? null:(byte[])iv.clone());

    }

   /**

     * Tests for equality between the specified object and this

     * object. Two RC2ParameterSpec objects are considered equal if their

     * effective key sizes and IVs are equal.

     * (Two IV references are considered equal if both are <tt>null</tt>.)

     *

     * @param obj the object to test for equality with this object.

     *

     * @return true if the objects are considered equal, false if

     * <code>obj</code> is null or otherwise.

     */

    public boolean equals(Object obj) {

        if (obj == this) {

            return true;

        }

        if (!(obj instanceof RC2ParameterSpec)) {

            return false;

        }

        RC2ParameterSpec other = (RC2ParameterSpec) obj;

        return ((effectiveKeyBits == other.effectiveKeyBits) &&

                java.util.Arrays.equals(iv, other.iv));

    }

    /**

     * Calculates a hash code value for the object.

     * Objects that are equal will also have the same hashcode.

     */

    public int hashCode() {

        int retval = 0;

        if (iv != null) {

            for (int i = 1; i < iv.length; i++) {

                retval += iv[i] * i;

            }

        }

        return (retval += effectiveKeyBits);

    }

}