view libtomcrypt/src/modes/ecb/ecb_start.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"

/**
   @file ecb_start.c
   ECB implementation, start chain, Tom St Denis
*/


#ifdef LTC_ECB_MODE

/**
   Initialize a ECB context
   @param cipher      The index of the cipher desired
   @param key         The secret key
   @param keylen      The length of the secret key (octets)
   @param num_rounds  Number of rounds in the cipher desired (0 for default)
   @param ecb         The ECB state to initialize
   @return CRYPT_OK if successful
*/
int ecb_start(int cipher, const unsigned char *key, int keylen, int num_rounds, symmetric_ECB *ecb)
{
   int err;
   LTC_ARGCHK(key != NULL);
   LTC_ARGCHK(ecb != NULL);

   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
      return err;
   }
   ecb->cipher = cipher;
   ecb->blocklen = cipher_descriptor[cipher].block_length;
   return cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ecb->key);
}

#endif

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