src/test/test_rng.c

   1 /* Copyright (c) 2016-2020, The Tor Project, Inc. */
   2 /* See LICENSE for licensing information */
   3
   4 /*
   5  * Example usage:
   6  *
   7  * ./src/test/test-rng --emit | dieharder -g 200 -a
   8  *
   9  * Remember, dieharder can tell you that your RNG is completely broken, but if
  10  * your RNG is not _completely_ broken, dieharder cannot tell you whether your
  11  * RNG is actually secure.
  12  */
  13
  14 #include "orconfig.h"
  15
  16 #ifdef HAVE_UNISTD_H
  17 #include <unistd.h>
  18 #endif
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <errno.h>
  22
  23 #include "lib/crypt_ops/crypto_rand.h"
  24
  25 int
  26 main(int argc, char **argv)
  27 {
  28   uint8_t buf[0x123];
  29
  30   if (argc != 2 || strcmp(argv[1], "--emit")) {
  31     fprintf(stderr, "If you want me to fill stdout with a bunch of random "
  32             "bytes, you need to say --emit.\n");
  33     return 1;
  34   }
  35
  36   if (crypto_seed_rng() < 0) {
  37     fprintf(stderr, "Can't seed RNG.\n");
  38     return 1;
  39   }
  40
  41 #if 0
  42   while (1) {
  43     crypto_rand(buf, sizeof(buf));
  44     if (write(1 /*stdout*/, buf, sizeof(buf)) != sizeof(buf)) {
  45       fprintf(stderr, "write() failed: %s\n", strerror(errno));
  46       return 1;
  47     }
  48   }
  49 #endif /* 0 */
  50
  51   crypto_fast_rng_t *rng = crypto_fast_rng_new();
  52   while (1) {
  53     crypto_fast_rng_getbytes(rng, buf, sizeof(buf));
  54     if (write(1 /*stdout*/, buf, sizeof(buf)) != sizeof(buf)) {
  55       fprintf(stderr, "write() failed: %s\n", strerror(errno));
  56       return 1;
  57     }
  58   }
  59 }