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Java > Open Source Codes > com > jcraft > jsch > jce > Random


1 /* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
2 /*
3 Copyright (c) 2002,2003,2004,2005,2006 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.jce;
31
32 import java.security.SecureRandom JavaDoc;
33
34 public class Random implements com.jcraft.jsch.Random{
35   private byte[] tmp=new byte[16];
36   private SecureRandom JavaDoc random=null;
37   public Random(){
38
39     // We hope that 'new SecureRandom()' will use NativePRNG algorithm
40 // on Sun's Java5 for GNU/Linux and Solaris.
41 // It seems NativePRNG refers to /dev/urandom and it must not be blocked,
42 // but NativePRNG is slower than SHA1PRNG ;-<
43 // TIPS: By adding option '-Djava.security.egd=file:/dev/./urandom'
44 // SHA1PRNG will be used instead of NativePRNG.
45 // On MacOSX, 'new SecureRandom()' will use NativePRNG algorithm and
46 // it is also slower than SHA1PRNG.
47 // On Windows, 'new SecureRandom()' will use SHA1PRNG algorithm.
48 random=new SecureRandom JavaDoc();
49
50     /*
51     try{
52       random=SecureRandom.getInstance("SHA1PRNG");
53       return;
54     }
55     catch(java.security.NoSuchAlgorithmException e){
56       // System.err.println(e);
57     }
58
59     // The following code is for IBM's JCE
60     try{
61       random=SecureRandom.getInstance("IBMSecureRandom");
62       return;
63     }
64     catch(java.security.NoSuchAlgorithmException ee){
65       //System.err.println(ee);
66     }
67     */
68   }
69   public void fill(byte[] foo, int start, int len){
70     /*
71     // This case will not become true in our usage.
72     if(start==0 && foo.length==len){
73       random.nextBytes(foo);
74       return;
75     }
76     */
77     if(len>tmp.length){ tmp=new byte[len]; }
78     random.nextBytes(tmp);
79     System.arraycopy(tmp, 0, foo, start, len);
80   }
81 }
82
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