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/**
* featherweight – Keccak-based userspace pseudorandom number generator
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <alloca.h>
#include <libkeccak.h>
#include <argparser.h>
#ifndef URANDOM
# ifndef DEVDIR
# define DEVDIR "/dev"
# endif
# define URANDOM DEVDIR "/urandom"
#endif
#define USER_ERROR(string) \
(fprintf(stderr, "%s: %s.\n", execname, string), 1)
#define ADD(arg, desc, ...) \
(arg ? args_add_option(args_new_argumented(NULL, arg, 0, __VA_ARGS__, NULL), desc) \
: args_add_option(args_new_argumentless(NULL, 0, __VA_ARGS__, NULL), desc))
#define LAST(arg) \
(args_opts_get(arg)[args_opts_get_count(arg) - 1])
/**
* `argv[0]` from `main`
*/
static char* execname;
/**
* Convert `libkeccak_generalised_spec_t` to `libkeccak_spec_t` and check for errors
*
* @param gspec See `libkeccak_degeneralise_spec`
* @param spec See `libkeccak_degeneralise_spec`
* @return Zero on success, an appropriate exit value on error
*/
static int make_spec(libkeccak_generalised_spec_t* restrict gspec, libkeccak_spec_t* restrict spec)
{
int r;
#define TEST(CASE, STR) case LIBKECCAK_GENERALISED_SPEC_ERROR_##CASE: return USER_ERROR(STR)
if (r = libkeccak_degeneralise_spec(gspec, spec), r)
switch (r)
{
TEST (STATE_NONPOSITIVE, "the state size must be positive");
TEST (STATE_TOO_LARGE, "the state size is too large, may not exceed 1600");
TEST (STATE_MOD_25, "the state size must be a multiple of 25");
TEST (WORD_NONPOSITIVE, "the word size must be positive");
TEST (WORD_TOO_LARGE, "the word size is too large, may not exceed 64");
TEST (STATE_WORD_INCOHERENCY, "the state size must be exactly 25 times the word size");
TEST (CAPACITY_NONPOSITIVE, "the capacity must be positive");
TEST (CAPACITY_MOD_8, "the capacity must be a multiple of 8");
TEST (BITRATE_NONPOSITIVE, "the rate must be positive");
TEST (BITRATE_MOD_8, "the rate must be a multiple of 8");
TEST (OUTPUT_NONPOSITIVE, "the output size must be positive");
default:
return USER_ERROR("unknown error in algorithm parameters");
}
#undef TEST
#define TEST(CASE, STR) case LIBKECCAK_SPEC_ERROR_##CASE: return USER_ERROR(STR)
if (r = libkeccak_spec_check(spec), r)
switch (r)
{
TEST (BITRATE_NONPOSITIVE, "the rate size must be positive");
TEST (BITRATE_MOD_8, "the rate must be a multiple of 8");
TEST (CAPACITY_NONPOSITIVE, "the capacity must be positive");
TEST (CAPACITY_MOD_8, "the capacity must be a multiple of 8");
TEST (OUTPUT_NONPOSITIVE, "the output size must be positive");
TEST (STATE_TOO_LARGE, "the state size is too large, may not exceed 1600");
TEST (STATE_MOD_25, "the state size must be a multiple of 25");
TEST (WORD_NON_2_POTENT, "the word size must be a power of 2");
TEST (WORD_MOD_8, "the word size must be a multiple of 8");
default:
return USER_ERROR("unknown error in algorithm parameters");
}
#undef TEST
return 0;
}
/**
* Mane!
*
* @param argc The number of elements in `argv`
* @param argv Command line arguments
* @return Zero on and only on success
*/
int main(int argc, char** argv)
{
char* restrict generated_random = NULL;
libkeccak_generalised_spec_t gspec;
libkeccak_spec_t spec;
libkeccak_state_t state;
size_t length, ptr;
ssize_t got;
int r, fd = -1, verbose = 0;
execname = *argv;
memset(&state, 0, sizeof(libkeccak_state_t));
libkeccak_generalised_spec_initialise(&gspec);
args_init("Keccak-based userspace pseudorandom number generator",
"krandom [options...]", NULL,
NULL, 1, 0, args_standard_abbreviations);
ADD(NULL, "Display option summary", "-h", "--help");
ADD("RATE", "Select rate", "-R", "--bitrate", "--rate");
ADD("CAPACITY", "Select capacity", "-C", "--capacity");
ADD("SIZE", "Select output size", "-N", "-O", "--output-size", "--output");
ADD("SIZE", "Select state size", "-S", "-B", "--state-size", "--state");
ADD("SIZE", "Select word size", "-W", "--word-size", "--word");
ADD(NULL, "Be verbose", "-v", "--verbose");
args_parse(argc, argv);
if (args_opts_used("-h")) return args_help(0), args_dispose(), 0;
if (args_opts_used("-R")) gspec.bitrate = atol(LAST("-R"));
if (args_opts_used("-C")) gspec.capacity = atol(LAST("-C"));
if (args_opts_used("-N")) gspec.output = atol(LAST("-N"));
if (args_opts_used("-S")) gspec.state_size = atol(LAST("-S"));
if (args_opts_used("-W")) gspec.word_size = atol(LAST("-W"));
if (args_opts_used("-v")) verbose = 1;
if ((r = make_spec(&gspec, &spec)))
goto done;
if (verbose)
{
fprintf(stderr, "%s: " "rate: %li\n", execname, gspec.bitrate);
fprintf(stderr, "%s: " "capacity: %li\n", execname, gspec.capacity);
fprintf(stderr, "%s: " "output size: %li\n", execname, gspec.output);
fprintf(stderr, "%s: " "state size: %li\n", execname, gspec.state_size);
fprintf(stderr, "%s: " "word size: %li\n", execname, gspec.word_size);
}
libkeccak_state_initialise(&state, &spec);
fd = open(URANDOM, O_RDONLY);
if (fd < 0)
goto fail;
for (ptr = 0, length = sizeof(state.S); ptr < length;)
{
got = read(fd, (char*)(state.S) + ptr, length - ptr);
if (got <= 0)
goto fail;
ptr += (size_t)got;
}
close(fd), fd = -1;
length = (size_t)((spec.output + 7) / 8);
generated_random = malloc(length);
if (generated_random == NULL)
goto fail;
for (;;)
{
libkeccak_squeeze(&state, generated_random);
got = write(STDOUT_FILENO, generated_random, length);
if (got >= 0)
continue;
if (errno == EPIPE)
break;
goto fail;
}
done:
if (fd >= 0)
close(fd);
args_dispose();
free(generated_random);
libkeccak_state_fast_destroy(&state);
return r;
fail:
perror(execname);
r = 2;
goto done;
}
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