/*

 * Copyright (c) 2004, 2019, 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

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package sun.security.krb5.internal.crypto;

import sun.security.krb5.Checksum;

import sun.security.krb5.KrbCryptoException;

import sun.security.krb5.internal.*;

import java.security.GeneralSecurityException;

/*

 * This class encapsulates the checksum type for AES256

 *

 * @author Seema Malkani

 */

public class HmacSha1Aes256CksumType extends CksumType {

    public HmacSha1Aes256CksumType() {

    }

    public int confounderSize() {

        return 16;

    }

    public int cksumType() {

        return Checksum.CKSUMTYPE_HMAC_SHA1_96_AES256;

    }

    public boolean isKeyed() {

        return true;

    }

    public int cksumSize() {

        return 12;  // bytes

    }

    public int keyType() {

        return Krb5.KEYTYPE_AES;

    }

    public int keySize() {

        return 32;   // bytes

    }

    /**

     * Calculates keyed checksum.

     * @param data the data used to generate the checksum.

     * @param size length of the data.

     * @param key the key used to encrypt the checksum.

     * @return keyed checksum.

     */

    public byte[] calculateChecksum(byte[] data, int size, byte[] key,

        int usage) throws KrbCryptoException {

         try {

            return Aes256.calculateChecksum(key, usage, data, 0, size);

         } catch (GeneralSecurityException e) {

            KrbCryptoException ke = new KrbCryptoException(e.getMessage());

            ke.initCause(e);

            throw ke;

         }

    }

    /**

     * Verifies keyed checksum.

     * @param data the data.

     * @param size the length of data.

     * @param key the key used to encrypt the checksum.

     * @param checksum the checksum.

     * @return true if verification is successful.

     */

    public boolean verifyChecksum(byte[] data, int size,

        byte[] key, byte[] checksum, int usage) throws KrbCryptoException {

         try {

            byte[] newCksum = Aes256.calculateChecksum(key, usage, data,

                                                        0, size);

            return isChecksumEqual(checksum, newCksum);

         } catch (GeneralSecurityException e) {

            KrbCryptoException ke = new KrbCryptoException(e.getMessage());

            ke.initCause(e);

            throw ke;

         }

    }

}