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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  
21  package org.apache.directory.server.kerberos.shared.crypto.encryption;
22  
23  
24  import java.util.Collections;
25  import java.util.HashMap;
26  import java.util.Iterator;
27  import java.util.Map;
28  import java.util.Set;
29  
30  import javax.security.auth.kerberos.KerberosKey;
31  import javax.security.auth.kerberos.KerberosPrincipal;
32  
33  import org.apache.directory.server.kerberos.shared.messages.value.EncryptionKey;
34  
35  
36  /**
37   * A factory class for producing {@link KerberosKey}'s.  For a list of desired cipher
38   * types, Kerberos string-to-key functions are used to derive keys for DES-, DES3-, AES-,
39   * and RC4-based encryption types.
40   *
41   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
42   * @version $Rev$, $Date$
43   */
44  public class KerberosKeyFactory
45  {
46      /** A map of default encryption types mapped to cipher names. */
47      private static final Map<EncryptionType, String> DEFAULT_CIPHERS;
48  
49      static
50      {
51          Map<EncryptionType, String> map = new HashMap<EncryptionType, String>();
52  
53          map.put( EncryptionType.DES_CBC_MD5, "DES" );
54          map.put( EncryptionType.DES3_CBC_SHA1_KD, "DESede" );
55          map.put( EncryptionType.RC4_HMAC, "ArcFourHmac" );
56          map.put( EncryptionType.AES128_CTS_HMAC_SHA1_96, "AES128" );
57          map.put( EncryptionType.AES256_CTS_HMAC_SHA1_96, "AES256" );
58  
59          DEFAULT_CIPHERS = Collections.unmodifiableMap( map );
60      }
61  
62  
63      /**
64       * Get a map of KerberosKey's for a given principal name and passphrase.  The default set
65       * of encryption types is used.
66       * 
67       * @param principalName The principal name to use for key derivation.
68       * @param passPhrase The passphrase to use for key derivation.
69       * @return The map of KerberosKey's.
70       */
71      public static Map<EncryptionType, EncryptionKey> getKerberosKeys( String principalName, String passPhrase )
72      {
73          return getKerberosKeys( principalName, passPhrase, DEFAULT_CIPHERS.keySet() );
74      }
75  
76  
77      /**
78       * Get a list of KerberosKey's for a given principal name and passphrase and list of cipher
79       * types to derive keys for.
80       *
81       * @param principalName The principal name to use for key derivation.
82       * @param passPhrase The passphrase to use for key derivation.
83       * @param ciphers The set of ciphers to derive keys for.
84       * @return The list of KerberosKey's.
85       */
86      public static Map<EncryptionType, EncryptionKey> getKerberosKeys( String principalName, String passPhrase,
87          Set<EncryptionType> ciphers )
88      {
89          KerberosPrincipal principal = new KerberosPrincipal( principalName );
90          Map<EncryptionType, EncryptionKey> kerberosKeys = new HashMap<EncryptionType, EncryptionKey>();
91  
92          Iterator<EncryptionType> it = ciphers.iterator();
93          while ( it.hasNext() )
94          {
95              EncryptionType encryptionType = it.next();
96              String algorithm = DEFAULT_CIPHERS.get( encryptionType );
97  
98              try
99              {
100                 KerberosKey kerberosKey = new KerberosKey( principal, passPhrase.toCharArray(), algorithm );
101                 EncryptionKey encryptionKey = new EncryptionKey( encryptionType, kerberosKey.getEncoded(), kerberosKey
102                     .getVersionNumber() );
103 
104                 kerberosKeys.put( encryptionType, encryptionKey );
105             }
106             catch ( IllegalArgumentException iae )
107             {
108                 // Algorithm AES256 not enabled by policy.
109                 // Algorithm ArcFourHmac not supported by IBM JREs.
110                 // Algorithm DESede not supported by IBM JREs.
111             }
112         }
113 
114         return kerberosKeys;
115     }
116 }