001    /*
002     * Cumulus4j - Securing your data in the cloud - http://cumulus4j.org
003     * Copyright (C) 2011 NightLabs Consulting GmbH
004     *
005     * This program is free software: you can redistribute it and/or modify
006     * it under the terms of the GNU Affero General Public License as
007     * published by the Free Software Foundation, either version 3 of the
008     * License, or (at your option) any later version.
009     *
010     * This program is distributed in the hope that it will be useful,
011     * but WITHOUT ANY WARRANTY; without even the implied warranty of
012     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013     * GNU Affero General Public License for more details.
014     *
015     * You should have received a copy of the GNU Affero General Public License
016     * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017     */
018    package org.cumulus4j.crypto.internal.symmetric;
019    
020    import java.security.SecureRandom;
021    
022    import org.bouncycastle.crypto.KeyGenerationParameters;
023    import org.bouncycastle.crypto.params.KeyParameter;
024    import org.cumulus4j.crypto.SecretKeyGenerator;
025    
026    /**
027     * Default implementation of {@link SecretKeyGenerator}.
028     *
029     * @author Marco หงุ่ยตระกูล-Schulze - marco at nightlabs dot de
030     */
031    public class SecretKeyGeneratorImpl implements SecretKeyGenerator
032    {
033            private int strength;
034            private int strengthInBytes;
035            private SecureRandom random;
036    
037            @Override
038            public void init(KeyGenerationParameters params)
039            {
040                    strength = 0;
041                    random = null;
042    
043                    if (params != null) {
044                            strength = params.getStrength();
045                            random = params.getRandom();
046                    }
047    
048                    if (strength < 1)
049                            strength = 256;
050    
051                    if (random == null)
052                            random = new SecureRandom();
053    
054                    strengthInBytes = (strength + 7) / 8;
055            }
056    
057            @Override
058            public KeyParameter generateKey()
059            {
060                    if (random == null)
061                            throw new IllegalStateException("init(...) was not yet called!");
062    
063                    byte[] key = new byte[strengthInBytes];
064                    random.nextBytes(key);
065                    return new KeyParameter(key);
066            }
067    
068    }