Mercurial > dropbear
view libtomcrypt/src/hashes/sha2/sha224.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. */ /** @param sha224.c LTC_SHA-224 new NIST standard based off of LTC_SHA-256 truncated to 224 bits (Tom St Denis) */ #include "tomcrypt.h" #if defined(LTC_SHA224) && defined(LTC_SHA256) const struct ltc_hash_descriptor sha224_desc = { "sha224", 10, 28, 64, /* OID */ { 2, 16, 840, 1, 101, 3, 4, 2, 4, }, 9, &sha224_init, &sha256_process, &sha224_done, &sha224_test, NULL }; /* init the sha256 er... sha224 state ;-) */ /** Initialize the hash state @param md The hash state you wish to initialize @return CRYPT_OK if successful */ int sha224_init(hash_state * md) { LTC_ARGCHK(md != NULL); md->sha256.curlen = 0; md->sha256.length = 0; md->sha256.state[0] = 0xc1059ed8UL; md->sha256.state[1] = 0x367cd507UL; md->sha256.state[2] = 0x3070dd17UL; md->sha256.state[3] = 0xf70e5939UL; md->sha256.state[4] = 0xffc00b31UL; md->sha256.state[5] = 0x68581511UL; md->sha256.state[6] = 0x64f98fa7UL; md->sha256.state[7] = 0xbefa4fa4UL; return CRYPT_OK; } /** Terminate the hash to get the digest @param md The hash state @param out [out] The destination of the hash (28 bytes) @return CRYPT_OK if successful */ int sha224_done(hash_state * md, unsigned char *out) { unsigned char buf[32]; int err; LTC_ARGCHK(md != NULL); LTC_ARGCHK(out != NULL); err = sha256_done(md, buf); XMEMCPY(out, buf, 28); #ifdef LTC_CLEAN_STACK zeromem(buf, sizeof(buf)); #endif return err; } /** Self-test the hash @return CRYPT_OK if successful, CRYPT_NOP if self-tests have been disabled */ int sha224_test(void) { #ifndef LTC_TEST return CRYPT_NOP; #else static const struct { const char *msg; unsigned char hash[28]; } tests[] = { { "abc", { 0x23, 0x09, 0x7d, 0x22, 0x34, 0x05, 0xd8, 0x22, 0x86, 0x42, 0xa4, 0x77, 0xbd, 0xa2, 0x55, 0xb3, 0x2a, 0xad, 0xbc, 0xe4, 0xbd, 0xa0, 0xb3, 0xf7, 0xe3, 0x6c, 0x9d, 0xa7 } }, { "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", { 0x75, 0x38, 0x8b, 0x16, 0x51, 0x27, 0x76, 0xcc, 0x5d, 0xba, 0x5d, 0xa1, 0xfd, 0x89, 0x01, 0x50, 0xb0, 0xc6, 0x45, 0x5c, 0xb4, 0xf5, 0x8b, 0x19, 0x52, 0x52, 0x25, 0x25 } }, }; int i; unsigned char tmp[28]; hash_state md; for (i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) { sha224_init(&md); sha224_process(&md, (unsigned char*)tests[i].msg, (unsigned long)strlen(tests[i].msg)); sha224_done(&md, tmp); if (compare_testvector(tmp, sizeof(tmp), tests[i].hash, sizeof(tests[i].hash), "SHA224", i)) { return CRYPT_FAIL_TESTVECTOR; } } return CRYPT_OK; #endif } #endif /* defined(LTC_SHA224) && defined(LTC_SHA256) */ /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */