/*
 * Copyright (c) 2017, 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 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 aes128-cts-sha256
 */

public class HmacSha2Aes128CksumType extends CksumType {

    public HmacSha2Aes128CksumType() {
    }

    public int confounderSize() {
        return 16;
    }

    public int cksumType() {
        return Checksum.CKSUMTYPE_HMAC_SHA256_128_AES128;
    }

    public boolean isSafe() {
        return true;
    }

    public int cksumSize() {
        return 16;  // bytes
    }

    public int keyType() {
        return Krb5.KEYTYPE_AES;
    }

    public int keySize() {
        return 16;   // bytes
    }

    public byte[] calculateChecksum(byte[] data, int size) {
        return null;
    }

    /**
     * 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[] calculateKeyedChecksum(byte[] data, int size, byte[] key,
        int usage) throws KrbCryptoException {

         try {
            return Aes128Sha2.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 verifyKeyedChecksum(byte[] data, int size,
        byte[] key, byte[] checksum, int usage) throws KrbCryptoException {

         try {
            byte[] newCksum = Aes128Sha2.calculateChecksum(key, usage,
                                                        data, 0, size);
            return isChecksumEqual(checksum, newCksum);
         } catch (GeneralSecurityException e) {
            KrbCryptoException ke = new KrbCryptoException(e.getMessage());
            ke.initCause(e);
            throw ke;
         }
    }
}