view libtomcrypt/src/mac/pmac/pmac_memory_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 6dba84798cd5
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"
#include <stdarg.h>

/**
   @file pmac_memory_multi.c
   PMAC implementation, process multiple blocks of memory, by Tom St Denis
*/

#ifdef LTC_PMAC

/**
   PMAC multiple blocks of memory
   @param cipher   The index of the cipher desired
   @param key      The secret key
   @param keylen   The length of the secret key (octets)
   @param out      [out] Destination for the authentication tag
   @param outlen   [in/out] The max size and resulting size of the authentication tag
   @param in       The data you wish to send through PMAC
   @param inlen    The length of data you wish to send through PMAC (octets)
   @param ...      tuples of (data,len) pairs to PMAC, terminated with a (NULL,x) (x=don't care)
   @return CRYPT_OK if successful
*/
int pmac_memory_multi(int cipher,
                const unsigned char *key, unsigned long  keylen,
                      unsigned char *out, unsigned long *outlen,
                const unsigned char *in,  unsigned long  inlen, ...)
{
   int                  err;
   pmac_state          *pmac;
   va_list              args;
   const unsigned char *curptr;
   unsigned long        curlen;

   LTC_ARGCHK(key    != NULL);
   LTC_ARGCHK(in     != NULL);
   LTC_ARGCHK(out    != NULL);
   LTC_ARGCHK(outlen != NULL);

   /* allocate ram for pmac state */
   pmac = XMALLOC(sizeof(pmac_state));
   if (pmac == NULL) {
      return CRYPT_MEM;
   }

   if ((err = pmac_init(pmac, cipher, key, keylen)) != CRYPT_OK) {
      goto LBL_ERR;
   }
   va_start(args, inlen);
   curptr = in;
   curlen = inlen;
   for (;;) {
      /* process buf */
      if ((err = pmac_process(pmac, curptr, curlen)) != CRYPT_OK) {
         goto LBL_ERR;
      }
      /* step to next */
      curptr = va_arg(args, const unsigned char*);
      if (curptr == NULL) {
         break;
      }
      curlen = va_arg(args, unsigned long);
   }
   if ((err = pmac_done(pmac, out, outlen)) != CRYPT_OK) {
      goto LBL_ERR;
   }
LBL_ERR:
#ifdef LTC_CLEAN_STACK
   zeromem(pmac, sizeof(pmac_state));
#endif
   XFREE(pmac);
   va_end(args);
   return err;
}

#endif

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