view libtomcrypt/demos/constants.c @ 1790:42745af83b7d

Introduce extra delay before closing unauthenticated sessions To make it harder for attackers, introduce a delay to keep an unauthenticated session open a bit longer, thus blocking a connection slot until after the delay. Without this, while there is a limit on the amount of attempts an attacker can make at the same time (MAX_UNAUTH_PER_IP), the time taken by dropbear to handle one attempt is still short and thus for each of the allowed parallel attempts many attempts can be chained one after the other. The attempt rate is then: "MAX_UNAUTH_PER_IP / <process time of one attempt>". With the delay, this rate becomes: "MAX_UNAUTH_PER_IP / UNAUTH_CLOSE_DELAY".
author Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
date Wed, 15 Feb 2017 13:53:04 +0100
parents e9dba7abd939
children
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 */
#include "tomcrypt.h"

#if defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L
#include <libgen.h>
#else
#define basename(x) x
#endif

/**
  @file demo_crypt_constants.c

  Demo how to get various constants to dynamic languages
  like Python

  Larry Bugbee, February 2013
*/

static void _print_line(const char* cmd, const char* desc)
{
   printf("  %-16s - %s\n", cmd, desc);
}

int main(int argc, char **argv)
{
   if (argc == 1) {
      /* given a specific constant name, get and print its value */
      char name[] = "CTR_COUNTER_BIG_ENDIAN";
      int value;
      char *names_list;
      unsigned int names_list_len;

      if (crypt_get_constant(name, &value) != 0) exit(EXIT_FAILURE);
      printf("\n  %s is %d \n\n", name, value);

      /* get and print the length of the names (and values) list */

      if (crypt_list_all_constants(NULL, &names_list_len) != 0) exit(EXIT_FAILURE);
      printf("  need to allocate %u bytes \n\n", names_list_len);

      /* get and print the names (and values) list */
      if ((names_list = malloc(names_list_len)) == NULL) exit(EXIT_FAILURE);
      if (crypt_list_all_constants(names_list, &names_list_len) != 0) exit(EXIT_FAILURE);
      printf("  supported constants:\n\n%s\n\n", names_list);
      free(names_list);
   } else if (argc == 2) {
      if (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) {
         char* base = strdup(basename(argv[0]));
         printf("Usage: %s [-a] [-s name]\n\n", base);
         _print_line("<no argument>", "The old behavior of the demo");
         _print_line("-a", "Only lists all constants");
         _print_line("-s name", "List a single constant given as argument");
         _print_line("-h", "The help you're looking at");
         free(base);
      } else if (strcmp(argv[1], "-a") == 0) {
         char *names_list;
         unsigned int names_list_len;
         /* get and print the length of the names (and values) list */
         if (crypt_list_all_constants(NULL, &names_list_len) != 0) exit(EXIT_FAILURE);
         /* get and print the names (and values) list */
         if ((names_list = malloc(names_list_len)) == NULL) exit(EXIT_FAILURE);
         if (crypt_list_all_constants(names_list, &names_list_len) != 0) exit(EXIT_FAILURE);
         printf("%s\n", names_list);
         free(names_list);
      }
   } else if (argc == 3) {
      if (strcmp(argv[1], "-s") == 0) {
         int value;
         if (crypt_get_constant(argv[2], &value) != 0) exit(EXIT_FAILURE);
         printf("%s,%u\n", argv[2], value);
      }
   }

   return 0;
}


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