Mercurial > dropbear
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 |
line wrap: on
line source
/* 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 /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */