Mercurial > dropbear
view libtomcrypt/src/pk/rsa/rsa_sign_saltlen_get.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 rsa_sign_saltlen_get.c Retrieve the maximum size of the salt, Steffen Jaeckel. */ #ifdef LTC_MRSA /** Retrieve the maximum possible size of the salt when creating a PKCS#1 PSS signature. @param padding Type of padding (LTC_PKCS_1_PSS only) @param hash_idx The index of the desired hash @param key The RSA key @return The maximum salt length in bytes or INT_MAX on error. */ int rsa_sign_saltlen_get_max_ex(int padding, int hash_idx, rsa_key *key) { int ret = INT_MAX; LTC_ARGCHK(key != NULL); if ((hash_is_valid(hash_idx) == CRYPT_OK) && (padding == LTC_PKCS_1_PSS)) { ret = rsa_get_size(key); if (ret < INT_MAX) { ret -= (hash_descriptor[hash_idx].hashsize + 2); } /* if */ } /* if */ return ret; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */