view libtomcrypt/src/encauth/ocb/ocb_done_encrypt.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.
 */

/**
   @file ocb_done_encrypt.c
   OCB implementation, terminate encryption, by Tom St Denis
*/
#include "tomcrypt.h"

#ifdef LTC_OCB_MODE

/**
   Terminate an encryption OCB state
   @param ocb       The OCB state
   @param pt        Remaining plaintext (if any)
   @param ptlen     The length of the plaintext (octets)
   @param ct        [out] The ciphertext (if any)
   @param tag       [out] The tag for the OCB stream
   @param taglen    [in/out] The max size and resulting size of the tag
   @return CRYPT_OK if successful
*/
int ocb_done_encrypt(ocb_state *ocb, const unsigned char *pt, unsigned long ptlen,
                     unsigned char *ct, unsigned char *tag, unsigned long *taglen)
{
   LTC_ARGCHK(ocb    != NULL);
   LTC_ARGCHK(pt     != NULL);
   LTC_ARGCHK(ct     != NULL);
   LTC_ARGCHK(tag    != NULL);
   LTC_ARGCHK(taglen != NULL);
   return s_ocb_done(ocb, pt, ptlen, ct, tag, taglen, 0);
}

#endif


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