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.io.decoder;
021    
022    
023    import java.io.IOException;
024    import java.util.Enumeration;
025    
026    import org.apache.directory.server.kerberos.shared.crypto.encryption.EncryptionType;
027    import org.apache.directory.server.kerberos.shared.messages.value.EncryptedData;
028    import org.apache.directory.shared.asn1.der.ASN1InputStream;
029    import org.apache.directory.shared.asn1.der.DEREncodable;
030    import org.apache.directory.shared.asn1.der.DERInteger;
031    import org.apache.directory.shared.asn1.der.DEROctetString;
032    import org.apache.directory.shared.asn1.der.DERSequence;
033    import org.apache.directory.shared.asn1.der.DERTaggedObject;
034    
035    
036    /**
037     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
038     * @version $Rev: 587682 $, $Date: 2007-10-24 00:47:43 +0200 (Wed, 24 Oct 2007) $
039     */
040    public class EncryptedDataDecoder
041    {
042        /**
043         * Decodes a byte array into an {@link EncryptedData}.
044         *
045         * @param encodedEncryptedData
046         * @return The {@link EncryptedData}.
047         * @throws IOException
048         */
049        public static EncryptedData decode( byte[] encodedEncryptedData ) throws IOException
050        {
051            ASN1InputStream ais = new ASN1InputStream( encodedEncryptedData );
052    
053            DERSequence sequence = ( DERSequence ) ais.readObject();
054    
055            return decode( sequence );
056        }
057    
058    
059        /**
060         * Decodes a {@link DERSequence} into an {@link EncryptedData}.
061         * 
062         * EncryptedData ::=   SEQUENCE {
063         *             etype[0]     INTEGER, -- EncryptionEngine
064         *             kvno[1]      INTEGER OPTIONAL,
065         *             cipher[2]    OCTET STRING -- ciphertext
066         * }
067         * 
068         * @param sequence 
069         * @return The {@link EncryptedData}.
070         */
071        public static EncryptedData decode( DERSequence sequence )
072        {
073            EncryptedData encryptedData = new EncryptedData();
074    
075            for ( Enumeration<DEREncodable> e = sequence.getObjects(); e.hasMoreElements(); )
076            {
077                DERTaggedObject object = ( DERTaggedObject ) e.nextElement();
078                int tag = object.getTagNo();
079                DEREncodable derObject = object.getObject();
080    
081                switch ( tag )
082                {
083                    case 0:
084                        DERInteger etype = ( DERInteger ) derObject;
085                        encryptedData.setEType( EncryptionType.getTypeByOrdinal( etype.intValue() ) );
086                        break;
087                        
088                    case 1:
089                        DERInteger kvno = ( DERInteger ) derObject;
090                        encryptedData.setKvno( kvno.intValue() );
091                        break;
092                        
093                    case 2:
094                        DEROctetString cipher = ( DEROctetString ) derObject;
095                        encryptedData.setCipher( cipher.getOctets() );
096                        break;
097                }
098            }
099    
100            return encryptedData;
101        }
102    }