1 // SPDX-License-Identifier: BSD-2-Clause
2 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
3 *
4 * LibTomCrypt is a library that provides various cryptographic
5 * algorithms in a highly modular and flexible manner.
6 *
7 * The library is free for all purposes without any express
8 * guarantee it works.
9 */
10 #include "tomcrypt_private.h"
11
12 /**
13 @file dsa_make_key.c
14 DSA implementation, generate a DSA key
15 */
16
17 #ifdef LTC_MDSA
18
19 /**
20 Create a DSA key
21 @param prng An active PRNG state
22 @param wprng The index of the PRNG desired
23 @param key [in/out] Where to store the created key
24 @return CRYPT_OK if successful.
25 */
dsa_generate_key(prng_state * prng,int wprng,dsa_key * key)26 int dsa_generate_key(prng_state *prng, int wprng, dsa_key *key)
27 {
28 int err;
29
30 LTC_ARGCHK(key != NULL);
31 LTC_ARGCHK(ltc_mp.name != NULL);
32
33 /* so now we have our DH structure, generator g, order q, modulus p
34 Now we need a random exponent [mod q] and it's power g^x mod p
35 */
36 /* private key x should be from range: 1 <= x <= q-1 (see FIPS 186-4 B.1.2) */
37 if ((err = rand_bn_upto(key->x, key->q, prng, wprng)) != CRYPT_OK) { return err; }
38 if ((err = mp_exptmod(key->g, key->x, key->p, key->y)) != CRYPT_OK) { return err; }
39 key->type = PK_PRIVATE;
40
41 return CRYPT_OK;
42 }
43
44 #endif
45
46 /* ref: $Format:%D$ */
47 /* git commit: $Format:%H$ */
48 /* commit time: $Format:%ai$ */
49