GordianMacOutputStream.java

/*
 * GordianKnot: Security Suite
 * Copyright 2012-2026. Tony Washer
 *
 * Licensed 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 io.github.tonywasher.joceanus.gordianknot.impl.core.stream;

import io.github.tonywasher.joceanus.gordianknot.api.mac.GordianMac;

import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;

/**
 * Output stream mac implementation.
 */
public class GordianMacOutputStream
        extends GordianOutputStream {
    /**
     * The MAC.
     */
    private final GordianMac theMac;

    /**
     * The digest result.
     */
    private byte[] theDigest;

    /**
     * The result.
     */
    private byte[] theResult;

    /**
     * The data length.
     */
    private long theDataLen;

    /**
     * Constructor.
     *
     * @param pMac    the MAC
     * @param pOutput the underlying output stream
     */
    GordianMacOutputStream(final GordianMac pMac,
                           final OutputStream pOutput) {
        super(pOutput);
        theMac = pMac;
    }

    /**
     * Obtain the MAC.
     *
     * @return the MAC
     */
    public GordianMac getMac() {
        return theMac;
    }

    /**
     * Obtain the Result.
     *
     * @return the result
     */
    public byte[] getResult() {
        return theResult == null
                ? null
                : Arrays.copyOf(theResult, theResult.length);
    }

    /**
     * Obtain the dataLength.
     *
     * @return the length
     */
    long getDataLen() {
        return theDataLen;
    }

    @Override
    protected void processData(final byte[] pBytes,
                               final int pOffset,
                               final int pLength) throws IOException {
        /* Update the MAC and write bytes to underlying stream */
        theMac.update(pBytes, pOffset, pLength);
        theDataLen += pLength;
        writeToStream(pBytes, pOffset, pLength);
    }

    /**
     * Record the digest.
     *
     * @param pDigest the digest
     */
    void setDigest(final byte[] pDigest) {
        /* Record the digest */
        theDigest = pDigest;
    }

    @Override
    protected void finishData() {
        theMac.update(theDigest);
        theResult = theMac.finish();
    }
}