KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > com > jcraft > jsch > jcraft > HMAC


1 /* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
2 /*
3 Copyright (c) 2006 ymnk, JCraft,Inc. All rights reserved.
4
5 Redistribution and use in source and binary forms, with or without
6 modification, are permitted provided that the following conditions are met:
7
8   1. Redistributions of source code must retain the above copyright notice,
9      this list of conditions and the following disclaimer.
10
11   2. Redistributions in binary form must reproduce the above copyright
12      notice, this list of conditions and the following disclaimer in
13      the documentation and/or other materials provided with the distribution.
14
15   3. The names of the authors may not be used to endorse or promote products
16      derived from this software without specific prior written permission.
17
18 THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
19 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
20 FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
21 INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
22 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
24 OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
26 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
27 EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 package com.jcraft.jsch.jcraft;
31
32 import java.security.*;
33
34 class HMAC{
35
36   /*
37    * Refer to RFC2104.
38    *
39    * H(K XOR opad, H(K XOR ipad, text))
40    *
41    * where K is an n byte key
42    * ipad is the byte 0x36 repeated 64 times
43    * opad is the byte 0x5c repeated 64 times
44    * and text is the data being protected
45    */
46   private static final int B=64;
47   private byte[] k_ipad=null;
48   private byte[] k_opad=null;
49
50   private MessageDigest md=null;
51
52   private int bsize=0;
53
54   protected void setH(MessageDigest md){
55     this.md=md;
56     bsize=md.getDigestLength();
57   }
58
59   public int getBlockSize(){return bsize;};
60   public void init(byte[] key) throws Exception JavaDoc{
61     if(key.length>bsize){
62       byte[] tmp=new byte[bsize];
63       System.arraycopy(key, 0, tmp, 0, bsize);
64       key=tmp;
65     }
66
67     /* if key is longer than B bytes reset it to key=MD5(key) */
68     if(key.length>B){
69       md.update(key, 0, key.length);
70       key=md.digest();
71     }
72
73     k_ipad=new byte[B];
74     System.arraycopy(key, 0, k_ipad, 0, key.length);
75     k_opad=new byte[B];
76     System.arraycopy(key, 0, k_opad, 0, key.length);
77
78     /* XOR key with ipad and opad values */
79     for(int i=0; i<B; i++) {
80       k_ipad[i]^=(byte)0x36;
81       k_opad[i]^=(byte)0x5c;
82     }
83
84     md.update(k_ipad, 0, B);
85   }
86
87   private final byte[] tmp=new byte[4];
88   public void update(int i){
89     tmp[0]=(byte)(i>>>24);
90     tmp[1]=(byte)(i>>>16);
91     tmp[2]=(byte)(i>>>8);
92     tmp[3]=(byte)i;
93     update(tmp, 0, 4);
94   }
95
96   public void update(byte foo[], int s, int l){
97     md.update(foo, s, l);
98   }
99
100   public void doFinal(byte[] buf, int offset){
101     byte[] result=md.digest();
102     md.update(k_opad, 0, B);
103     md.update(result, 0, bsize);
104     try{md.digest(buf, offset, bsize);}catch(Exception JavaDoc e){}
105     md.update(k_ipad, 0, B);
106   }
107 }
108
Popular Tags