Mercurial > dropbear
view libtomcrypt/src/hashes/sha2/sha512_224.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 sha512_224.c SHA512/224 hash included in sha512.c */ #include "tomcrypt.h" #if defined(LTC_SHA512_224) && defined(LTC_SHA512) const struct ltc_hash_descriptor sha512_224_desc = { "sha512-224", 15, 28, 128, /* OID */ { 2, 16, 840, 1, 101, 3, 4, 2, 5, }, 9, &sha512_224_init, &sha512_process, &sha512_224_done, &sha512_224_test, NULL }; /** Initialize the hash state @param md The hash state you wish to initialize @return CRYPT_OK if successful */ int sha512_224_init(hash_state * md) { LTC_ARGCHK(md != NULL); md->sha512.curlen = 0; md->sha512.length = 0; md->sha512.state[0] = CONST64(0x8C3D37C819544DA2); md->sha512.state[1] = CONST64(0x73E1996689DCD4D6); md->sha512.state[2] = CONST64(0x1DFAB7AE32FF9C82); md->sha512.state[3] = CONST64(0x679DD514582F9FCF); md->sha512.state[4] = CONST64(0x0F6D2B697BD44DA8); md->sha512.state[5] = CONST64(0x77E36F7304C48942); md->sha512.state[6] = CONST64(0x3F9D85A86A1D36C8); md->sha512.state[7] = CONST64(0x1112E6AD91D692A1); return CRYPT_OK; } /** Terminate the hash to get the digest @param md The hash state @param out [out] The destination of the hash (48 bytes) @return CRYPT_OK if successful */ int sha512_224_done(hash_state * md, unsigned char *out) { unsigned char buf[64]; LTC_ARGCHK(md != NULL); LTC_ARGCHK(out != NULL); if (md->sha512.curlen >= sizeof(md->sha512.buf)) { return CRYPT_INVALID_ARG; } sha512_done(md, buf); XMEMCPY(out, buf, 28); #ifdef LTC_CLEAN_STACK zeromem(buf, sizeof(buf)); #endif return CRYPT_OK; } /** Self-test the hash @return CRYPT_OK if successful, CRYPT_NOP if self-tests have been disabled */ int sha512_224_test(void) { #ifndef LTC_TEST return CRYPT_NOP; #else static const struct { const char *msg; unsigned char hash[28]; } tests[] = { { "abc", { 0x46, 0x34, 0x27, 0x0F, 0x70, 0x7B, 0x6A, 0x54, 0xDA, 0xAE, 0x75, 0x30, 0x46, 0x08, 0x42, 0xE2, 0x0E, 0x37, 0xED, 0x26, 0x5C, 0xEE, 0xE9, 0xA4, 0x3E, 0x89, 0x24, 0xAA } }, { "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu", { 0x23, 0xFE, 0xC5, 0xBB, 0x94, 0xD6, 0x0B, 0x23, 0x30, 0x81, 0x92, 0x64, 0x0B, 0x0C, 0x45, 0x33, 0x35, 0xD6, 0x64, 0x73, 0x4F, 0xE4, 0x0E, 0x72, 0x68, 0x67, 0x4A, 0xF9 } }, }; int i; unsigned char tmp[28]; hash_state md; for (i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) { sha512_224_init(&md); sha512_224_process(&md, (unsigned char*)tests[i].msg, (unsigned long)strlen(tests[i].msg)); sha512_224_done(&md, tmp); if (compare_testvector(tmp, sizeof(tmp), tests[i].hash, sizeof(tests[i].hash), "SHA512-224", i)) { return CRYPT_FAIL_TESTVECTOR; } } return CRYPT_OK; #endif } #endif /* defined(LTC_SHA384) && defined(LTC_SHA512) */ /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */