Mercurial > dropbear
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 /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */