001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *  
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *  
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License. 
018 *  
019 */
020package org.apache.directory.server.kerberos.shared.crypto.encryption;
021
022
023import java.security.NoSuchAlgorithmException;
024import java.util.Collections;
025import java.util.EnumMap;
026import java.util.HashMap;
027import java.util.Map;
028
029import javax.crypto.KeyGenerator;
030import javax.crypto.SecretKey;
031
032import org.apache.directory.server.i18n.I18n;
033import org.apache.directory.shared.kerberos.codec.types.EncryptionType;
034import org.apache.directory.shared.kerberos.components.EncryptionKey;
035import org.apache.directory.shared.kerberos.exceptions.ErrorType;
036import org.apache.directory.shared.kerberos.exceptions.KerberosException;
037
038
039/**
040 * A factory class for producing random keys, suitable for use as session keys.  For a
041 * list of desired cipher types, Kerberos random-to-key functions are used to derive
042 * keys for DES-, DES3-, AES-, and RC4-based encryption types.
043 *
044 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
045 */
046public class RandomKeyFactory
047{
048    /** A map of default encryption types mapped to cipher names. */
049    private static final Map<EncryptionType, String> DEFAULT_CIPHERS;
050
051    static
052    {
053        EnumMap<EncryptionType, String> map = new EnumMap<>( EncryptionType.class );
054
055        map.put( EncryptionType.DES_CBC_MD5, "DES" );
056        map.put( EncryptionType.DES3_CBC_SHA1_KD, "DESede" );
057        map.put( EncryptionType.RC4_HMAC, "RC4" );
058        map.put( EncryptionType.AES128_CTS_HMAC_SHA1_96, "AES" );
059        map.put( EncryptionType.AES256_CTS_HMAC_SHA1_96, "AES" );
060
061        DEFAULT_CIPHERS = Collections.unmodifiableMap( map );
062    }
063
064
065    /**
066     * Get a map of random keys.  The default set of encryption types is used.
067     * 
068     * @return The map of random keys.
069     * @throws KerberosException 
070     */
071    public static Map<EncryptionType, EncryptionKey> getRandomKeys() throws KerberosException
072    {
073        Map<EncryptionType, EncryptionKey> map = new HashMap<>();
074
075        for ( EncryptionType encryptionType : DEFAULT_CIPHERS.keySet() )
076        {
077            map.put( encryptionType, getRandomKey( encryptionType ) );
078        }
079
080        return map;
081    }
082
083
084    /**
085     * Get a new random key for a given {@link EncryptionType}.
086     * 
087     * @param encryptionType 
088     * 
089     * @return The new random key.
090     * @throws KerberosException 
091     */
092    public static EncryptionKey getRandomKey( EncryptionType encryptionType ) throws KerberosException
093    {
094        String algorithm = DEFAULT_CIPHERS.get( encryptionType );
095
096        if ( algorithm == null )
097        {
098            throw new KerberosException( ErrorType.KDC_ERR_ETYPE_NOSUPP, I18n.err( I18n.ERR_616,
099                encryptionType.getName() ) );
100        }
101
102        try
103        {
104            KeyGenerator keyGenerator = KeyGenerator.getInstance( algorithm );
105
106            if ( encryptionType.equals( EncryptionType.AES128_CTS_HMAC_SHA1_96 ) )
107            {
108                keyGenerator.init( 128 );
109            }
110
111            if ( encryptionType.equals( EncryptionType.AES256_CTS_HMAC_SHA1_96 ) )
112            {
113                keyGenerator.init( 256 );
114            }
115
116            SecretKey key = keyGenerator.generateKey();
117
118            byte[] keyBytes = key.getEncoded();
119
120            return new EncryptionKey( encryptionType, keyBytes );
121        }
122        catch ( NoSuchAlgorithmException nsae )
123        {
124            throw new KerberosException( ErrorType.KDC_ERR_ETYPE_NOSUPP, nsae );
125        }
126    }
127}