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
|
/***************************************************************************
* libdisorder: A Library for Measuring Byte Stream Entropy
* Copyright (C) 2010 Michael E. Locasto
*
* This program 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.
*
* This program 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 this program; if not, write to the:
* Free Software Foundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* $Id$
**************************************************************************/
#include "../include/disorder.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#define LIMIT LIBDO_BUFFER_LEN
/**
* Open and read /dev/urandom, filling a buffer of size LIMIT. After
* filing the buffer, calculate the entropy of the buffer. Repeat
* forever.
*
*/
int
main(int argc,
char* argv[])
{
float entropy_value = 0.0;
long long current_run = 0L;
char* buffer = NULL;
unsigned char c;
int x = 0;
FILE* fin=NULL;
char* itr=NULL;
int i = 0;
fin = fopen("/dev/urandom","r");
if(NULL==fin)
{
perror("main():");
return -1;
}
buffer = (char*)calloc(LIMIT, sizeof(char));
if(NULL==buffer)
{
perror("main():");
return -2;
}
for(;;)
{
itr = buffer;
for(i=0;i<LIMIT;i++)
{
x = fgetc(fin);
c = (unsigned char)x;
*itr=c;
itr++;
}
//NB: doing this caluculation here may allow /dev/unrandom to
//recover sufficiently to never show a decrease in entropy.
//Using a larger buffer or using another thread to perform this
//calculation while the main thread continues to fill the buffer
//may provide the ability to observe a decrease in entropy.
entropy_value = shannon_H(buffer, LIMIT);
fprintf(stdout,
"[%8lld] entropy: %f maxent: %f ratio: %f\n",
current_run,
entropy_value,
get_max_entropy(),
get_entropy_ratio()
);
current_run++;
fflush(stdout);
}
free(buffer);
buffer=NULL;
if(EOF!=fclose(fin))
perror("exiting main():");
fin=NULL;
return 0;
}
|
