3 * $Id: noise.h,v 1.2 1999/12/10 23:29:48 mdw Exp $
5 * Acquisition of environmental noise (Unix specific)
7 * (c) 1998 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * Catacomb is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.2 1999/12/10 23:29:48 mdw
34 * Change header file guard names.
36 * Revision 1.1 1999/09/03 08:41:12 mdw
41 #ifndef CATACOMB_NOISE_H
42 #define CATACOMB_NOISE_H
48 /*----- Header files ------------------------------------------------------*/
50 #include <sys/types.h>
52 #ifndef CATACOMB_RAND_H
56 /*----- Noise source definition -------------------------------------------*/
58 extern rand_source noise_source
;
60 /*----- Magic numbers -----------------------------------------------------*/
62 #define NOISE_NOSETUID ((uid_t)-1)
63 #define NOISE_NOSETGID ((gid_t)-1)
65 /*----- Functions provided ------------------------------------------------*/
67 /* --- @noise_timer@ --- *
69 * Arguments: @rand_pool *r@ = pointer to a randomness pool
71 * Returns: Nonzero if some randomness was contributed.
73 * Use: Contributes the current time to the randomness pool.
74 * A guess at the number of useful bits contributed is made,
75 * based on first and second order bit differences. This isn't
76 * ever-so reliable, but it's better than nothing.
79 extern int noise_timer(rand_pool */
*r*/
);
81 /* --- @noise_devrandom@ --- *
83 * Arguments: @rand_pool *r@ = pointer to a randomness pool
85 * Returns: Nonzero if some randomness was contributed.
87 * Use: Attempts to obtain some randomness from the system entropy
88 * pool. All bits from the device are assumed to be good.
91 extern int noise_devrandom(rand_pool */
*r*/
);
93 /* --- @noise_setid@ --- *
95 * Arguments: @uid_t uid@ = uid to set
96 * @gid_t gid@ = gid to set
100 * Use: Sets the user and group ids to be used by @noise_filter@
101 * when running child processes. This is useful to avoid
102 * giving shell commands (even carefully written ones) undue
106 extern void noise_setid(uid_t
/*uid*/, gid_t
/*gid*/);
108 /* --- @noise_filter@ --- *
110 * Arguments: @rand_pool *r@ = pointer to a randomness pool
111 * @int good@ = number of good bits per 1024 bits
112 * @const char *c@ = shell command to run
114 * Returns: Nonzero if some randomness was contributed.
116 * Use: Attempts to execute a shell command, and dump it into the
117 * randomness pool. A very rough estimate of the number of
118 * good bits is made, based on the size of the command's output.
119 * This function calls @waitpid@, so be careful. Before execing
120 * the command, the process uid and gid are set to the values
121 * given to @noise_setid@, and an attempt is made to reset the
122 * list of supplementary groups. The environment passed to
123 * the command has been severly lobotimized. If the command
124 * fails to complete within a short time period, it is killed.
125 * Paranoid use of close-on-exec flags for file descriptors is
129 extern int noise_filter(rand_pool */
*r*/
, int /*good*/, const char */
*c*/
);
131 /* --- @noise_acquire@ --- *
133 * Arguments: @rand_pool *r@ = pointer to a randomness pool
137 * Use: Acquires some randomness from somewhere.
140 extern void noise_acquire(rand_pool */
*r*/
);
142 /*----- That's all, folks -------------------------------------------------*/