view libtomcrypt/src/math/multi.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"

#ifdef LTC_MPI
#include <stdarg.h>

int ltc_init_multi(void **a, ...)
{
   void    **cur = a;
   int       np  = 0;
   va_list   args;

   va_start(args, a);
   while (cur != NULL) {
       if (mp_init(cur) != CRYPT_OK) {
          /* failed */
          va_list clean_list;

          va_start(clean_list, a);
          cur = a;
          while (np--) {
              mp_clear(*cur);
              cur = va_arg(clean_list, void**);
          }
          va_end(clean_list);
          va_end(args);
          return CRYPT_MEM;
       }
       ++np;
       cur = va_arg(args, void**);
   }
   va_end(args);
   return CRYPT_OK;
}

void ltc_deinit_multi(void *a, ...)
{
   void     *cur = a;
   va_list   args;

   va_start(args, a);
   while (cur != NULL) {
       mp_clear(cur);
       cur = va_arg(args, void *);
   }
   va_end(args);
}

void ltc_cleanup_multi(void **a, ...)
{
   void **cur = a;
   va_list args;

   va_start(args, a);
   while (cur != NULL) {
      if (*cur != NULL) {
         mp_clear(*cur);
         *cur = NULL;
      }
      cur = va_arg(args, void**);
   }
   va_end(args);
}

#endif

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