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Java utility collections, development by Nervousync Studio (NSYC)
There is a newer version: 1.2.1
/*
 * Licensed to the Nervousync Studio (NSYC) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.nervousync.security.digest;

import org.bouncycastle.crypto.Mac;
import org.nervousync.commons.core.Globals;
import org.nervousync.security.SecureProvider;
import org.nervousync.exceptions.crypto.CryptoException;
import org.nervousync.utils.StringUtils;

import java.security.MessageDigest;
import java.util.Arrays;

/**
 * The type Base digest provider.
 */
public abstract class BaseDigestProvider extends SecureProvider {

    private final boolean macMode;
    private final MessageDigest messageDigest;
    private final Mac hmac;

    /**
     * Instantiates a new Base digest provider.
     *
     * @param algorithm the algorithm
     * @param keyBytes  the key bytes
     * @throws CryptoException the crypto exception
     */
    protected BaseDigestProvider(String algorithm, byte[] keyBytes) throws CryptoException {
        if (StringUtils.isEmpty(algorithm)) {
            throw new CryptoException("Unknown algorithm! ");
        }
        this.macMode = algorithm.toUpperCase().contains("HMAC");
        this.messageDigest = this.macMode ? null : this.initDigest(algorithm);
        this.hmac = this.macMode ? this.initHmac(algorithm, keyBytes) : null;
    }

    /**
     * Init digest message digest.
     *
     * @param algorithm the algorithm
     * @return the message digest
     * @throws CryptoException the crypto exception
     */
    protected abstract MessageDigest initDigest(String algorithm) throws CryptoException;

    /**
     * Init hmac mac.
     *
     * @param algorithm the algorithm
     * @param keyBytes  the key bytes
     * @return the mac
     * @throws CryptoException the crypto exception
     */
    protected abstract Mac initHmac(String algorithm, byte[] keyBytes) throws CryptoException;

    @Override
    public final void append(byte[] dataBytes, int position, int length) throws CryptoException {
        if (dataBytes.length < (position + length)) {
            throw new CryptoException("Data bytes invalid!");
        }
        if (this.macMode) {
            this.hmac.update(dataBytes, position, length);
        } else {
            this.messageDigest.update(dataBytes, position, length);
        }
    }

    @Override
    public final byte[] finish(byte[] dataBytes, int position, int length) throws CryptoException {
        if (dataBytes.length < (position + length)) {
            throw new CryptoException("Data bytes invalid!");
        }
        this.append(dataBytes, position, length);
        byte[] result;
        if (this.macMode) {
            result = new byte[this.hmac.getMacSize()];
            this.hmac.doFinal(result, 0);
        } else {
            result = this.messageDigest.digest();
        }
        this.reset();
        return result;
    }

    @Override
    public final boolean verify(byte[] signature) {
        byte[] calcResult;
        if (this.macMode) {
            calcResult = new byte[this.hmac.getMacSize()];
            this.hmac.doFinal(calcResult, 0);
        } else {
            calcResult = this.messageDigest.digest();
        }
        boolean result = Arrays.equals(calcResult, signature);
        this.reset();
        return result;
    }

    @Override
    public final void reset() {
        if (this.macMode) {
            this.hmac.reset();
        } else {
            this.messageDigest.reset();
        }
    }

    /**
     * Mac length int.
     *
     * @return the int
     */
    public int macLength() {
        return this.macMode ? this.hmac.getMacSize() : Globals.DEFAULT_VALUE_INT;
    }
}