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Diffstat (limited to 'src/util/crypto_random.c')
-rw-r--r-- | src/util/crypto_random.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/src/util/crypto_random.c b/src/util/crypto_random.c new file mode 100644 index 000000000..3f7ac4dd3 --- /dev/null +++ b/src/util/crypto_random.c | |||
@@ -0,0 +1,136 @@ | |||
1 | /* | ||
2 | This file is part of GNUnet. | ||
3 | (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors) | ||
4 | |||
5 | GNUnet is free software; you can redistribute it and/or modify | ||
6 | it under the terms of the GNU General Public License as published | ||
7 | by the Free Software Foundation; either version 2, or (at your | ||
8 | option) any later version. | ||
9 | |||
10 | GNUnet is distributed in the hope that it will be useful, but | ||
11 | WITHOUT ANY WARRANTY; without even the implied warranty of | ||
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
13 | General Public License for more details. | ||
14 | |||
15 | You should have received a copy of the GNU General Public License | ||
16 | along with GNUnet; see the file COPYING. If not, write to the | ||
17 | Free Software Foundation, Inc., 59 Temple Place - Suite 330, | ||
18 | Boston, MA 02111-1307, USA. | ||
19 | |||
20 | */ | ||
21 | |||
22 | /** | ||
23 | * @file util/crypto_random.c | ||
24 | * @brief functions to gather random numbers | ||
25 | * @author Christian Grothoff | ||
26 | */ | ||
27 | #include "platform.h" | ||
28 | #include "gnunet_common.h" | ||
29 | #include "gnunet_crypto_lib.h" | ||
30 | #include <gcrypt.h> | ||
31 | |||
32 | /** | ||
33 | * @return a random value in the interval [0,i[. | ||
34 | */ | ||
35 | unsigned int | ||
36 | GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, unsigned int i) | ||
37 | { | ||
38 | #ifdef gcry_fast_random_poll | ||
39 | static unsigned int invokeCount; | ||
40 | #endif | ||
41 | unsigned int ret; | ||
42 | |||
43 | GNUNET_assert (i > 0); | ||
44 | |||
45 | if (mode == GNUNET_CRYPTO_QUALITY_STRONG) | ||
46 | { | ||
47 | /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */ | ||
48 | #ifdef gcry_fast_random_poll | ||
49 | if ((invokeCount++ % 256) == 0) | ||
50 | gcry_fast_random_poll (); | ||
51 | #endif | ||
52 | ret = rand (); /* in case gcry_randomize fails, | ||
53 | we at least get a pseudo- | ||
54 | random number this way */ | ||
55 | gcry_randomize ((unsigned char *) &ret, | ||
56 | sizeof (unsigned int), GCRY_STRONG_RANDOM); | ||
57 | return ret % i; | ||
58 | } | ||
59 | else | ||
60 | { | ||
61 | ret = i * ((double) RANDOM () / RAND_MAX); | ||
62 | if (ret >= i) | ||
63 | ret = i - 1; | ||
64 | return ret; | ||
65 | } | ||
66 | } | ||
67 | |||
68 | |||
69 | /** | ||
70 | * Get an array with a random permutation of the | ||
71 | * numbers 0...n-1. | ||
72 | * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive) | ||
73 | * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise | ||
74 | * @param n the size of the array | ||
75 | * @return the permutation array (allocated from heap) | ||
76 | */ | ||
77 | unsigned int * | ||
78 | GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n) | ||
79 | { | ||
80 | unsigned int *ret; | ||
81 | unsigned int i; | ||
82 | unsigned int tmp; | ||
83 | unsigned int x; | ||
84 | |||
85 | GNUNET_assert (n > 0); | ||
86 | ret = GNUNET_malloc (n * sizeof (int)); | ||
87 | for (i = 0; i < n; i++) | ||
88 | ret[i] = i; | ||
89 | for (i = 0; i < n; i++) | ||
90 | { | ||
91 | x = GNUNET_CRYPTO_random_u32 (mode, n); | ||
92 | tmp = ret[x]; | ||
93 | ret[x] = ret[i]; | ||
94 | ret[i] = tmp; | ||
95 | } | ||
96 | return ret; | ||
97 | } | ||
98 | |||
99 | /** | ||
100 | * Random on unsigned 64-bit values. | ||
101 | */ | ||
102 | unsigned long long | ||
103 | GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, | ||
104 | unsigned long long u) | ||
105 | { | ||
106 | unsigned long long ret; | ||
107 | |||
108 | GNUNET_assert (u > 0); | ||
109 | if (mode == GNUNET_CRYPTO_QUALITY_STRONG) | ||
110 | { | ||
111 | gcry_randomize ((unsigned char *) &ret, | ||
112 | sizeof (unsigned long long), GCRY_STRONG_RANDOM); | ||
113 | return ret % u; | ||
114 | } | ||
115 | else | ||
116 | { | ||
117 | ret = u * ((double) RANDOM () / RAND_MAX); | ||
118 | if (ret >= u) | ||
119 | ret = u - 1; | ||
120 | return ret; | ||
121 | } | ||
122 | } | ||
123 | |||
124 | /** | ||
125 | * This function should only be called in testcases | ||
126 | * where strong entropy gathering is not desired | ||
127 | * (for example, for hostkey generation). | ||
128 | */ | ||
129 | void | ||
130 | GNUNET_CRYPTO_random_disable_entropy_gathering () | ||
131 | { | ||
132 | gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0); | ||
133 | } | ||
134 | |||
135 | |||
136 | /* end of crypto_random.c */ | ||