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 */
020 package org.apache.directory.server.kerberos.shared.crypto.encryption;
021
022
023 import java.security.NoSuchAlgorithmException;
024 import java.util.Collections;
025 import java.util.HashMap;
026 import java.util.Iterator;
027 import java.util.Map;
028 import java.util.Set;
029
030 import javax.crypto.KeyGenerator;
031 import javax.crypto.SecretKey;
032
033 import org.apache.directory.server.i18n.I18n;
034 import org.apache.directory.server.kerberos.shared.exceptions.ErrorType;
035 import org.apache.directory.server.kerberos.shared.exceptions.KerberosException;
036 import org.apache.directory.server.kerberos.shared.messages.value.EncryptionKey;
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 * @version $Rev$, $Date$
046 */
047 public class RandomKeyFactory
048 {
049 /** A map of default encryption types mapped to cipher names. */
050 private static final Map<EncryptionType, String> DEFAULT_CIPHERS;
051
052 static
053 {
054 Map<EncryptionType, String> map = new HashMap<EncryptionType, String>();
055
056 map.put( EncryptionType.DES_CBC_MD5, "DES" );
057 map.put( EncryptionType.DES3_CBC_SHA1_KD, "DESede" );
058 map.put( EncryptionType.RC4_HMAC, "RC4" );
059 map.put( EncryptionType.AES128_CTS_HMAC_SHA1_96, "AES" );
060 map.put( EncryptionType.AES256_CTS_HMAC_SHA1_96, "AES" );
061
062 DEFAULT_CIPHERS = Collections.unmodifiableMap( map );
063 }
064
065
066 /**
067 * Get a map of random keys. The default set of encryption types is used.
068 *
069 * @return The map of random keys.
070 * @throws KerberosException
071 */
072 public static Map<EncryptionType, EncryptionKey> getRandomKeys() throws KerberosException
073 {
074 return getRandomKeys( DEFAULT_CIPHERS.keySet() );
075 }
076
077
078 /**
079 * Get a map of random keys for a list of cipher types to derive keys for.
080 *
081 * @param ciphers The list of ciphers to derive keys for.
082 * @return The list of KerberosKey's.
083 * @throws KerberosException
084 */
085 public static Map<EncryptionType, EncryptionKey> getRandomKeys( Set<EncryptionType> ciphers )
086 throws KerberosException
087 {
088 Map<EncryptionType, EncryptionKey> map = new HashMap<EncryptionType, EncryptionKey>();
089
090 Iterator<EncryptionType> it = ciphers.iterator();
091 while ( it.hasNext() )
092 {
093 EncryptionType type = it.next();
094 map.put( type, getRandomKey( type ) );
095 }
096
097 return map;
098 }
099
100
101 /**
102 * Get a new random key for a given {@link EncryptionType}.
103 *
104 * @param encryptionType
105 *
106 * @return The new random key.
107 * @throws KerberosException
108 */
109 public static EncryptionKey getRandomKey( EncryptionType encryptionType ) throws KerberosException
110 {
111 String algorithm = DEFAULT_CIPHERS.get( encryptionType );
112
113 if ( algorithm == null )
114 {
115 throw new KerberosException( ErrorType.KDC_ERR_ETYPE_NOSUPP, I18n.err( I18n.ERR_616, encryptionType.getName() ) );
116 }
117
118 try
119 {
120 KeyGenerator keyGenerator = KeyGenerator.getInstance( algorithm );
121
122 if ( encryptionType.equals( EncryptionType.AES128_CTS_HMAC_SHA1_96 ) )
123 {
124 keyGenerator.init( 128 );
125 }
126
127 if ( encryptionType.equals( EncryptionType.AES256_CTS_HMAC_SHA1_96 ) )
128 {
129 keyGenerator.init( 256 );
130 }
131
132 SecretKey key = keyGenerator.generateKey();
133
134 byte[] keyBytes = key.getEncoded();
135
136 return new EncryptionKey( encryptionType, keyBytes );
137 }
138 catch ( NoSuchAlgorithmException nsae )
139 {
140 throw new KerberosException( ErrorType.KDC_ERR_ETYPE_NOSUPP, nsae );
141 }
142 }
143 }