1 /* IALG.java --
2    Copyright (C) 2003, 2006 Free Software Foundation, Inc.
3 
4 This file is a part of GNU Classpath.
5 
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or (at
9 your option) any later version.
10 
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 General Public License for more details.
15 
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
19 USA
20 
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library.  Thus, the terms and
23 conditions of the GNU General Public License cover the whole
24 combination.
25 
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module.  An independent module is a module which is not derived from
33 or based on this library.  If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so.  If you do not wish to do so, delete this
36 exception statement from your version.  */
37 
38 
39 package gnu.javax.crypto.sasl.srp;
40 
41 import gnu.javax.crypto.mac.IMac;
42 import gnu.javax.crypto.mac.MacFactory;
43 
44 import java.security.InvalidKeyException;
45 import java.security.NoSuchAlgorithmException;
46 import java.util.HashMap;
47 
48 import javax.security.sasl.SaslException;
49 
50 /**
51  * A Factory class that returns IALG (Integrity Algorithm) instances that
52  * operate as described in the draft-burdis-cat-sasl-srp-04 and later.
53  */
54 public final class IALG
55     implements Cloneable
56 {
57   private IMac hmac;
58 
59   /** Private constructor to enforce instantiation through Factory method. */
IALG(final IMac hmac)60   private IALG(final IMac hmac)
61   {
62     super();
63 
64     this.hmac = hmac;
65   }
66 
67   /**
68    * Returns an instance of a SASL-SRP IALG implementation.
69    *
70    * @param algorithm the name of the HMAC algorithm.
71    * @return an instance of this object.
72    */
getInstance(final String algorithm)73   static synchronized IALG getInstance(final String algorithm)
74       throws SaslException
75   {
76     final IMac hmac;
77     hmac = MacFactory.getInstance(algorithm);
78     if (hmac == null)
79       throw new SaslException("getInstance()",
80                               new NoSuchAlgorithmException(algorithm));
81     return new IALG(hmac);
82   }
83 
clone()84   public Object clone() throws CloneNotSupportedException
85   {
86     return new IALG((IMac) hmac.clone());
87   }
88 
init(final KDF kdf)89   public void init(final KDF kdf) throws SaslException
90   {
91     try
92       {
93         final byte[] sk = kdf.derive(hmac.macSize());
94         final HashMap map = new HashMap();
95         map.put(IMac.MAC_KEY_MATERIAL, sk);
96         hmac.init(map);
97       }
98     catch (InvalidKeyException x)
99       {
100         throw new SaslException("getInstance()", x);
101       }
102   }
103 
update(final byte[] data)104   public void update(final byte[] data)
105   {
106     hmac.update(data, 0, data.length);
107   }
108 
update(final byte[] data, final int offset, final int length)109   public void update(final byte[] data, final int offset, final int length)
110   {
111     hmac.update(data, offset, length);
112   }
113 
doFinal()114   public byte[] doFinal()
115   {
116     return hmac.digest();
117   }
118 
119   /**
120    * Returns the length (in bytes) of this SASL SRP Integrity Algorithm.
121    *
122    * @return the length, in bytes, of this integrity protection algorithm.
123    */
length()124   public int length()
125   {
126     return hmac.macSize();
127   }
128 }
129