Mercurial > dropbear
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> |
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date | Mon, 15 Jun 2020 18:22:18 +0500 |
parents | 6dba84798cd5 |
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rev | line source |
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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: $Format:%ai$ */ |