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crypto: Add crypto_derive_sae_pwe_from_pt_ecc

This commit is contained in:
Denis Kenzior 2021-07-09 10:07:28 -05:00
parent f7b5ebd097
commit 77e387dd0c
2 changed files with 42 additions and 0 deletions
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39
src/crypto.c
View File

@ -1212,3 +1212,42 @@ struct l_ecc_point *crypto_derive_sae_pt_ecc(unsigned int group,
return l_steal_ptr(pt);
}
struct l_ecc_point *crypto_derive_sae_pwe_from_pt_ecc(const uint8_t *mac1,
const uint8_t *mac2,
const struct l_ecc_point *pt)
{
const struct l_ecc_curve *curve = l_ecc_point_get_curve(pt);
enum l_checksum_type hash;
size_t hash_len;
uint8_t sorted_macs[12];
uint8_t val_buf[64]; /* Max for SHA-512 */
struct l_ecc_scalar *val;
struct l_ecc_point *pwe;
if (!pt || !curve)
return false;
hash = ecc_hash_from_prime_len(l_ecc_curve_get_scalar_bytes(curve));
hash_len = l_checksum_digest_length(hash);
/*
* val = H(0n, MAX(STA-A-MAC, STA-B-MAC) || MIN(STA-A-MAC, STA-B-MAC))
*/
if (memcmp(mac1, mac2, 6) > 0) {
memcpy(sorted_macs, mac1, 6);
memcpy(sorted_macs + 6, mac2, 6);
} else {
memcpy(sorted_macs, mac2, 6);
memcpy(sorted_macs + 6, mac1, 6);
}
hkdf_extract(hash, NULL, 0, 1, val_buf,
sorted_macs, sizeof(sorted_macs));
val = l_ecc_scalar_new_reduced_1_to_n(curve, val_buf, hash_len);
pwe = l_ecc_point_new(curve);
l_ecc_point_multiply(pwe, val, pt);
l_ecc_scalar_free(val);
return pwe;
}

3
src/crypto.h
View File

@ -153,3 +153,6 @@ struct l_ecc_point *crypto_derive_sae_pt_ecc(unsigned int group,
const char *ssid,
const char *password,
const char *identifier);
struct l_ecc_point *crypto_derive_sae_pwe_from_pt_ecc(const uint8_t *mac1,
const uint8_t *mac2,
const struct l_ecc_point *pt);