001// SPDX-FileCopyrightText: 2018 Paul Schaub <vanitasvitae@fsfe.org>
002//
003// SPDX-License-Identifier: Apache-2.0
004
005package org.pgpainless.encryption_signing;
006
007import java.io.IOException;
008import java.io.OutputStream;
009import java.util.ArrayList;
010import java.util.List;
011import java.util.Set;
012import javax.annotation.Nonnull;
013
014import org.bouncycastle.openpgp.PGPException;
015import org.pgpainless.PGPainless;
016import org.pgpainless.algorithm.CompressionAlgorithm;
017import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
018import org.pgpainless.algorithm.negotiation.SymmetricKeyAlgorithmNegotiator;
019import org.pgpainless.key.SubkeyIdentifier;
020import org.slf4j.Logger;
021import org.slf4j.LoggerFactory;
022
023public class EncryptionBuilder implements EncryptionBuilderInterface {
024
025    private static final Logger LOGGER = LoggerFactory.getLogger(EncryptionBuilder.class);
026
027    private OutputStream outputStream;
028
029    @Override
030    public WithOptions onOutputStream(@Nonnull OutputStream outputStream) {
031        this.outputStream = outputStream;
032        return new WithOptionsImpl();
033    }
034
035    class WithOptionsImpl implements WithOptions {
036        @Override
037        public EncryptionStream withOptions(ProducerOptions options) throws PGPException, IOException {
038            if (options == null) {
039                throw new NullPointerException("ProducerOptions cannot be null.");
040            }
041            return new EncryptionStream(outputStream, options);
042        }
043    }
044
045    /**
046     * Negotiate the {@link SymmetricKeyAlgorithm} used for message encryption.
047     *
048     * @param encryptionOptions encryption options
049     * @return negotiated symmetric key algorithm
050     */
051    public static SymmetricKeyAlgorithm negotiateSymmetricEncryptionAlgorithm(EncryptionOptions encryptionOptions) {
052        List<Set<SymmetricKeyAlgorithm>> preferences = new ArrayList<>();
053        for (SubkeyIdentifier key : encryptionOptions.getKeyViews().keySet()) {
054            preferences.add(encryptionOptions.getKeyViews().get(key).getPreferredSymmetricKeyAlgorithms());
055        }
056
057        SymmetricKeyAlgorithm algorithm = SymmetricKeyAlgorithmNegotiator
058                .byPopularity()
059                .negotiate(
060                        PGPainless.getPolicy().getSymmetricKeyEncryptionAlgorithmPolicy(),
061                        encryptionOptions.getEncryptionAlgorithmOverride(),
062                        preferences);
063        LOGGER.debug("Negotiation resulted in {} being the symmetric encryption algorithm of choice.", algorithm);
064        return algorithm;
065    }
066
067    public static CompressionAlgorithm negotiateCompressionAlgorithm(ProducerOptions producerOptions) {
068        CompressionAlgorithm compressionAlgorithmOverride = producerOptions.getCompressionAlgorithmOverride();
069        if (compressionAlgorithmOverride != null) {
070            return compressionAlgorithmOverride;
071        }
072
073        // TODO: Negotiation
074
075        return PGPainless.getPolicy().getCompressionAlgorithmPolicy().defaultCompressionAlgorithm();
076    }
077}