/* * Copyright (c) 2011, Oracle and/or its affiliates. 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.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.crypto.spec; import java.security.spec.AlgorithmParameterSpec; /** * Specifies the set of parameters required by a {@link * javax.crypto.Cipher} using the Galois/Counter Mode (GCM) mode. * <p> * Simple block cipher modes (such as CBC) generally require only an * initialization vector (such as {@code IvParameterSpec}), * but GCM needs these parameters: * <ul> * <li>{@code IV}: Initialization Vector (IV) </li> * <li>{@code tLen}: length (in bits) of authentication tag T</li> * </ul> * <p> * In addition to the parameters described here, other GCM inputs/output * (Additional Authenticated Data (AAD), Keys, block ciphers, * plain/ciphertext and authentication tags) are handled in the {@code * Cipher} class.  <p> * Please see <a href="http://www.ietf.org/rfc/rfc5116.txt"> RFC 5116 * </a> for more information on the Authenticated Encryption with * Associated Data (AEAD) algorithm, and <a href= * "http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf"> * NIST Special Publication 800-38D</a>, "NIST Recommendation for Block * Cipher Modes of Operation:  Galois/Counter Mode (GCM) and GMAC." * <p> * The GCM specification states that {@code tLen} may only have the * values {128, 120, 112, 104, 96}, or {64, 32} for certain * applications.  Other values can be specified for this class, but not * all CSP implementations will support them. * * @see javax.crypto.Cipher * * @since 1.7 */public class GCMParameterSpec implements AlgorithmParameterSpec {     // Initialization Vector.  Could use IvParameterSpec, but that    // would add extra copies.    private byte[] iv;     // Required Tag length (in bits).    private int tLen;     /**     * Constructs a GCMParameterSpec using the specified authentication     * tag bit-length and IV buffer.     *     * @param tLen the authentication tag length (in bits)     * @param src the IV source buffer.  The contents of the buffer are     * copied to protect against subsequent modification.     *     * @throws IllegalArgumentException if {@code tLen} is negative,     * or {@code src} is null.     */    public GCMParameterSpec(int tLen, byte[] src) {        if (src == null) {            throw new IllegalArgumentException("src array is null");        }         init(tLen, src, 0, src.length);    }     /**     * Constructs a GCMParameterSpec object using the specified     * authentication tag bit-length and a subset of the specified     * buffer as the IV.     *     * @param tLen the authentication tag length (in bits)     * @param src the IV source buffer.  The contents of the     * buffer are copied to protect against subsequent modification.     * @param offset the offset in {@code src} where the IV starts     * @param len the number of IV bytes     *     * @throws IllegalArgumentException if {@code tLen} is negative,     * {@code src} is null, {@code len} or {@code offset} is negative,     * or the sum of {@code offset} and {@code len} is greater than the     * length of the {@code src} byte array.     */    public GCMParameterSpec(int tLen, byte[] src, int offset, int len) {        init(tLen, src, offset, len);    }     /*     * Check input parameters.     */    private void init(int tLen, byte[] src, int offset, int len) {        if (tLen < 0) {            throw new IllegalArgumentException(                "Length argument is negative");        }        this.tLen = tLen;         // Input sanity check        if ((src == null) ||(len < 0) || (offset < 0)                || ((len + offset) > src.length)) {            throw new IllegalArgumentException("Invalid buffer arguments");        }         iv = new byte[len];        System.arraycopy(src, offset, iv, 0, len);    }     /**     * Returns the authentication tag length.     *     * @return the authentication tag length (in bits)     */    public int getTLen() {        return tLen;    }     /**     * Returns the Initialization Vector (IV).     *     * @return the IV.  Creates a new array each time this method     * is called.     */    public byte[] getIV() {        return iv.clone();    }}