1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */
2 /* SPDX-License-Identifier: Unlicense */
3
4 #include "tomcrypt_private.h"
5
6 /**
7 @file ecc_make_key.c
8 ECC Crypto, Tom St Denis
9 */
10
11 #ifdef LTC_MECC
12
13 /**
14 Make a new ECC key
15 @param prng An active PRNG state
16 @param wprng The index of the PRNG you wish to use
17 @param keysize The keysize for the new key (in octets from 20 to 65 bytes)
18 @param key [out] Destination of the newly created key
19 @return CRYPT_OK if successful, upon error all allocated memory will be freed
20 */
ecc_make_key(prng_state * prng,int wprng,int keysize,ecc_key * key)21 int ecc_make_key(prng_state *prng, int wprng, int keysize, ecc_key *key)
22 {
23 int err;
24
25 if ((err = ecc_set_curve_by_size(keysize, key)) != CRYPT_OK) { return err; }
26 if ((err = ecc_generate_key(prng, wprng, key)) != CRYPT_OK) { return err; }
27 return CRYPT_OK;
28 }
29
ecc_make_key_ex(prng_state * prng,int wprng,ecc_key * key,const ltc_ecc_curve * cu)30 int ecc_make_key_ex(prng_state *prng, int wprng, ecc_key *key, const ltc_ecc_curve *cu)
31 {
32 int err;
33 if ((err = ecc_set_curve(cu, key)) != CRYPT_OK) { return err; }
34 if ((err = ecc_generate_key(prng, wprng, key)) != CRYPT_OK) { return err; }
35 return CRYPT_OK;
36 }
37
ecc_generate_key(prng_state * prng,int wprng,ecc_key * key)38 int ecc_generate_key(prng_state *prng, int wprng, ecc_key *key)
39 {
40 int err;
41
42 LTC_ARGCHK(ltc_mp.name != NULL);
43 LTC_ARGCHK(key != NULL);
44 LTC_ARGCHK(key->dp.size > 0);
45
46 /* ECC key pair generation according to FIPS-186-4 (B.4.2 Key Pair Generation by Testing Candidates):
47 * the generated private key k should be the range [1, order-1]
48 * a/ N = bitlen(order)
49 * b/ generate N random bits and convert them into big integer k
50 * c/ if k not in [1, order-1] go to b/
51 * e/ Q = k*G
52 */
53 if ((err = rand_bn_upto(key->k, key->dp.order, prng, wprng)) != CRYPT_OK) {
54 goto error;
55 }
56
57 /* make the public key */
58 if ((err = ltc_mp.ecc_ptmul(key->k, &key->dp.base, &key->pubkey, key->dp.A, key->dp.prime, 1)) != CRYPT_OK) {
59 goto error;
60 }
61 key->type = PK_PRIVATE;
62
63 /* success */
64 err = CRYPT_OK;
65 goto cleanup;
66
67 error:
68 ecc_free(key);
69 cleanup:
70 return err;
71 }
72
73 #endif
74