annotate libtomcrypt/src/pk/dsa/dsa_generate_key.c @ 1715:3974f087d9c0

Disallow leading lines before the ident for server (#102) Per RFC4253 4.2 clients must be able to process other lines of data before the version string, server behavior is not defined neither with MUST/SHOULD nor with MAY. If server process up to 50 lines too - it may cause too long hanging session with invalid/evil client that consume host resources and potentially may lead to DDoS on poor embedded boxes. Let's require first line from client to be version string and fail early if it's not - matches both RFC and real OpenSSH behavior.
author Vladislav Grishenko <themiron@users.noreply.github.com>
date Mon, 15 Jun 2020 18:22:18 +0500
parents 6dba84798cd5
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1471
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 */
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9 #include "tomcrypt.h"
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10
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11 /**
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12 @file dsa_make_key.c
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13 DSA implementation, generate a DSA key
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14 */
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15
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16 #ifdef LTC_MDSA
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17
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18 /**
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19 Create a DSA key
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20 @param prng An active PRNG state
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21 @param wprng The index of the PRNG desired
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22 @param key [in/out] Where to store the created key
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23 @return CRYPT_OK if successful.
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24 */
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25 int dsa_generate_key(prng_state *prng, int wprng, dsa_key *key)
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26 {
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27 int err;
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28
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29 LTC_ARGCHK(key != NULL);
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30 LTC_ARGCHK(ltc_mp.name != NULL);
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31
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32 /* so now we have our DH structure, generator g, order q, modulus p
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33 Now we need a random exponent [mod q] and it's power g^x mod p
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34 */
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35 /* private key x should be from range: 1 <= x <= q-1 (see FIPS 186-4 B.1.2) */
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36 if ((err = rand_bn_upto(key->x, key->q, prng, wprng)) != CRYPT_OK) { return err; }
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37 if ((err = mp_exptmod(key->g, key->x, key->p, key->y)) != CRYPT_OK) { return err; }
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38 key->type = PK_PRIVATE;
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39
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40 return CRYPT_OK;
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41 }
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42
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43 #endif
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44
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45 /* ref: $Format:%D$ */
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46 /* git commit: $Format:%H$ */
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47 /* commit time: $Format:%ai$ */