View Javadoc

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  package org.apache.directory.server.kerberos.shared.io.decoder;
21  
22  
23  import java.util.Enumeration;
24  
25  import org.apache.directory.server.kerberos.shared.crypto.checksum.ChecksumType;
26  import org.apache.directory.server.kerberos.shared.messages.value.Checksum;
27  import org.apache.directory.shared.asn1.der.DEREncodable;
28  import org.apache.directory.shared.asn1.der.DERInteger;
29  import org.apache.directory.shared.asn1.der.DEROctetString;
30  import org.apache.directory.shared.asn1.der.DERSequence;
31  import org.apache.directory.shared.asn1.der.DERTaggedObject;
32  
33  
34  /**
35   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
36   * @version $Rev: 588239 $, $Date: 2007-10-25 16:24:28 +0200 (Do, 25 Okt 2007) $
37   */
38  public class ChecksumDecoder
39  {
40      /**
41       * Checksum ::=   SEQUENCE {
42       *          cksumtype[0]   INTEGER,
43       *          checksum[1]    OCTET STRING
44       * }
45       * @param sequence 
46       * @return The {@link Checksum}.
47       */
48      public static Checksum decode( DERSequence sequence )
49      {
50          ChecksumType type = ChecksumType.NULL;
51          byte[] data = null;
52  
53          for ( Enumeration<DEREncodable> e = sequence.getObjects(); e.hasMoreElements(); )
54          {
55              DERTaggedObject object = ( DERTaggedObject ) e.nextElement();
56              int tag = object.getTagNo();
57              DEREncodable derObject = object.getObject();
58  
59              switch ( tag )
60              {
61                  case 0:
62                      DERInteger tag0 = ( DERInteger ) derObject;
63                      type = ChecksumType.getTypeByOrdinal( tag0.intValue() );
64                      break;
65                      
66                  case 1:
67                      DEROctetString tag1 = ( DEROctetString ) derObject;
68                      data = tag1.getOctets();
69                      break;
70              }
71          }
72  
73          return new Checksum( type, data );
74      }
75  }