diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/krandom.c | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/src/krandom.c b/src/krandom.c new file mode 100644 index 0000000..b049bc8 --- /dev/null +++ b/src/krandom.c @@ -0,0 +1,214 @@ +/** + * 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; +} + |