1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
/* BasePRNG.java --
Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc.
This file is a part of GNU Classpath.
GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.
GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Classpath; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA
Linking this library statically or dynamically with other modules is
making a combined work based on this library. Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.
As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module. An independent module is a module which is not derived from
or based on this library. If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so. If you do not wish to do so, delete this
exception statement from your version. */
package gnu.java.security.prng;
import java.util.Map;
/**
* An abstract class to facilitate implementing PRNG algorithms.
*/
public abstract class BasePRNG
implements IRandom
{
/** The canonical name prefix of the PRNG algorithm. */
protected String name;
/** Indicate if this instance has already been initialised or not. */
protected boolean initialised;
/** A temporary buffer to serve random bytes. */
protected byte[] buffer;
/** The index into buffer of where the next byte will come from. */
protected int ndx;
/**
* Trivial constructor for use by concrete subclasses.
*
* @param name the canonical name of this instance.
*/
protected BasePRNG(String name)
{
super();
this.name = name;
initialised = false;
buffer = new byte[0];
}
public String name()
{
return name;
}
public void init(Map attributes)
{
this.setup(attributes);
ndx = 0;
initialised = true;
}
public byte nextByte() throws IllegalStateException, LimitReachedException
{
if (! initialised)
throw new IllegalStateException();
return nextByteInternal();
}
public void nextBytes(byte[] out) throws IllegalStateException,
LimitReachedException
{
nextBytes(out, 0, out.length);
}
public void nextBytes(byte[] out, int offset, int length)
throws IllegalStateException, LimitReachedException
{
if (! initialised)
throw new IllegalStateException("not initialized");
if (length == 0)
return;
if (offset < 0 || length < 0 || offset + length > out.length)
throw new ArrayIndexOutOfBoundsException("offset=" + offset + " length="
+ length + " limit="
+ out.length);
if (ndx >= buffer.length)
{
fillBlock();
ndx = 0;
}
int count = 0;
while (count < length)
{
int amount = Math.min(buffer.length - ndx, length - count);
System.arraycopy(buffer, ndx, out, offset + count, amount);
count += amount;
ndx += amount;
if (ndx >= buffer.length)
{
fillBlock();
ndx = 0;
}
}
}
public void addRandomByte(byte b)
{
throw new UnsupportedOperationException("random state is non-modifiable");
}
public void addRandomBytes(byte[] buffer)
{
addRandomBytes(buffer, 0, buffer.length);
}
public void addRandomBytes(byte[] buffer, int offset, int length)
{
throw new UnsupportedOperationException("random state is non-modifiable");
}
public boolean isInitialised()
{
return initialised;
}
private byte nextByteInternal() throws LimitReachedException
{
if (ndx >= buffer.length)
{
this.fillBlock();
ndx = 0;
}
return buffer[ndx++];
}
public Object clone() throws CloneNotSupportedException
{
BasePRNG result = (BasePRNG) super.clone();
if (this.buffer != null)
result.buffer = (byte[]) this.buffer.clone();
return result;
}
public abstract void setup(Map attributes);
public abstract void fillBlock() throws LimitReachedException;
}
|
