Mercurial > dropbear
view libtomcrypt/src/mac/f9/f9_memory.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 f9_process.c f9 Support, Process a block through F9-MAC */ #ifdef LTC_F9_MODE /** f9-MAC a block of memory @param cipher Index of cipher to use @param key [in] Secret key @param keylen Length of key in octets @param in [in] Message to MAC @param inlen Length of input in octets @param out [out] Destination for the MAC tag @param outlen [in/out] Output size and final tag size Return CRYPT_OK on success. */ int f9_memory(int cipher, const unsigned char *key, unsigned long keylen, const unsigned char *in, unsigned long inlen, unsigned char *out, unsigned long *outlen) { f9_state *f9; int err; /* is the cipher valid? */ if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { return err; } /* Use accelerator if found */ if (cipher_descriptor[cipher].f9_memory != NULL) { return cipher_descriptor[cipher].f9_memory(key, keylen, in, inlen, out, outlen); } f9 = XCALLOC(1, sizeof(*f9)); if (f9 == NULL) { return CRYPT_MEM; } if ((err = f9_init(f9, cipher, key, keylen)) != CRYPT_OK) { goto done; } if ((err = f9_process(f9, in, inlen)) != CRYPT_OK) { goto done; } err = f9_done(f9, out, outlen); done: XFREE(f9); return err; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */