OpenSSL: Add wrapper functions for ECDH

These allow ECDH to be used with compressed public key encoding (only
x-coordinate). This is needed for FILS PFS and OWE.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2017-03-11 18:54:33 +02:00
parent 3d745aa7cb
commit ae1ec1aaf2
2 changed files with 247 additions and 2 deletions

View file

@ -1,6 +1,6 @@
/*
* Wrapper functions for crypto libraries
* Copyright (c) 2004-2013, Jouni Malinen <j@w1.fi>
* Copyright (c) 2004-2017, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
@ -832,4 +832,12 @@ int crypto_ec_point_cmp(const struct crypto_ec *e,
const struct crypto_ec_point *a,
const struct crypto_ec_point *b);
struct crypto_ecdh;
struct crypto_ecdh * crypto_ecdh_init(int group);
struct wpabuf * crypto_ecdh_get_pubkey(struct crypto_ecdh *ecdh, int inc_y);
struct wpabuf * crypto_ecdh_set_peerkey(struct crypto_ecdh *ecdh, int inc_y,
const u8 *key, size_t len);
void crypto_ecdh_deinit(struct crypto_ecdh *ecdh);
#endif /* CRYPTO_H */

View file

@ -1,6 +1,6 @@
/*
* Wrapper functions for OpenSSL libcrypto
* Copyright (c) 2004-2015, Jouni Malinen <j@w1.fi>
* Copyright (c) 2004-2017, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
@ -1363,6 +1363,7 @@ fail:
struct crypto_ec {
EC_GROUP *group;
int nid;
BN_CTX *bnctx;
BIGNUM *prime;
BIGNUM *order;
@ -1420,6 +1421,7 @@ struct crypto_ec * crypto_ec_init(int group)
if (e == NULL)
return NULL;
e->nid = nid;
e->bnctx = BN_CTX_new();
e->group = EC_GROUP_new_by_curve_name(nid);
e->prime = BN_new();
@ -1660,4 +1662,239 @@ int crypto_ec_point_cmp(const struct crypto_ec *e,
(const EC_POINT *) b, e->bnctx);
}
struct crypto_ecdh {
struct crypto_ec *ec;
EVP_PKEY *pkey;
};
struct crypto_ecdh * crypto_ecdh_init(int group)
{
struct crypto_ecdh *ecdh;
EVP_PKEY *params = NULL;
EVP_PKEY_CTX *pctx = NULL;
EVP_PKEY_CTX *kctx = NULL;
ecdh = os_zalloc(sizeof(*ecdh));
if (!ecdh)
goto fail;
ecdh->ec = crypto_ec_init(group);
if (!ecdh->ec)
goto fail;
pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_EC, NULL);
if (!pctx)
goto fail;
if (EVP_PKEY_paramgen_init(pctx) != 1) {
wpa_printf(MSG_ERROR,
"OpenSSL: EVP_PKEY_paramgen_init failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
if (EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, ecdh->ec->nid) != 1) {
wpa_printf(MSG_ERROR,
"OpenSSL: EVP_PKEY_CTX_set_ec_paramgen_curve_nid failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
if (EVP_PKEY_paramgen(pctx, &params) != 1) {
wpa_printf(MSG_ERROR, "OpenSSL: EVP_PKEY_paramgen failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
kctx = EVP_PKEY_CTX_new(params, NULL);
if (!kctx)
goto fail;
if (EVP_PKEY_keygen_init(kctx) != 1) {
wpa_printf(MSG_ERROR,
"OpenSSL: EVP_PKEY_keygen_init failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
if (EVP_PKEY_keygen(kctx, &ecdh->pkey) != 1) {
wpa_printf(MSG_ERROR, "OpenSSL: EVP_PKEY_keygen failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
done:
EVP_PKEY_free(params);
EVP_PKEY_CTX_free(pctx);
EVP_PKEY_CTX_free(kctx);
return ecdh;
fail:
crypto_ecdh_deinit(ecdh);
ecdh = NULL;
goto done;
}
struct wpabuf * crypto_ecdh_get_pubkey(struct crypto_ecdh *ecdh, int inc_y)
{
struct wpabuf *buf = NULL;
EC_KEY *eckey;
const EC_POINT *pubkey;
BIGNUM *x, *y = NULL;
int len = BN_num_bytes(ecdh->ec->prime);
int res;
eckey = EVP_PKEY_get1_EC_KEY(ecdh->pkey);
if (!eckey)
return NULL;
pubkey = EC_KEY_get0_public_key(eckey);
if (!pubkey)
return NULL;
x = BN_new();
if (inc_y) {
y = BN_new();
if (!y)
goto fail;
}
buf = wpabuf_alloc(inc_y ? 2 * len : len);
if (!x || !buf)
goto fail;
if (EC_POINT_get_affine_coordinates_GFp(ecdh->ec->group, pubkey,
x, y, ecdh->ec->bnctx) != 1) {
wpa_printf(MSG_ERROR,
"OpenSSL: EC_POINT_get_affine_coordinates_GFp failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
res = crypto_bignum_to_bin((struct crypto_bignum *) x,
wpabuf_put(buf, len), len, len);
if (res < 0)
goto fail;
if (inc_y) {
res = crypto_bignum_to_bin((struct crypto_bignum *) y,
wpabuf_put(buf, len), len, len);
if (res < 0)
goto fail;
}
done:
BN_clear_free(x);
BN_clear_free(y);
EC_KEY_free(eckey);
return buf;
fail:
wpabuf_free(buf);
buf = NULL;
goto done;
}
struct wpabuf * crypto_ecdh_set_peerkey(struct crypto_ecdh *ecdh, int inc_y,
const u8 *key, size_t len)
{
BIGNUM *x, *y = NULL;
EVP_PKEY_CTX *ctx = NULL;
EVP_PKEY *peerkey = NULL;
struct wpabuf *secret = NULL;
size_t secret_len;
EC_POINT *pub;
EC_KEY *eckey = NULL;
x = BN_bin2bn(key, inc_y ? len / 2 : len, NULL);
pub = EC_POINT_new(ecdh->ec->group);
if (!x || !pub)
goto fail;
if (inc_y) {
y = BN_bin2bn(key + len / 2, len / 2, NULL);
if (!y)
goto fail;
if (!EC_POINT_set_affine_coordinates_GFp(ecdh->ec->group, pub,
x, y,
ecdh->ec->bnctx)) {
wpa_printf(MSG_ERROR,
"OpenSSL: EC_POINT_set_affine_coordinates_GFp failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
} else if (!EC_POINT_set_compressed_coordinates_GFp(ecdh->ec->group,
pub, x, 0,
ecdh->ec->bnctx)) {
wpa_printf(MSG_ERROR,
"OpenSSL: EC_POINT_set_compressed_coordinates_GFp failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
if (!EC_POINT_is_on_curve(ecdh->ec->group, pub, ecdh->ec->bnctx)) {
wpa_printf(MSG_ERROR,
"OpenSSL: ECDH peer public key is not on curve");
goto fail;
}
eckey = EC_KEY_new_by_curve_name(ecdh->ec->nid);
if (!eckey || EC_KEY_set_public_key(eckey, pub) != 1) {
wpa_printf(MSG_ERROR,
"OpenSSL: EC_KEY_set_public_key failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
peerkey = EVP_PKEY_new();
if (!peerkey || EVP_PKEY_set1_EC_KEY(peerkey, eckey) != 1)
goto fail;
ctx = EVP_PKEY_CTX_new(ecdh->pkey, NULL);
if (!ctx || EVP_PKEY_derive_init(ctx) != 1 ||
EVP_PKEY_derive_set_peer(ctx, peerkey) != 1 ||
EVP_PKEY_derive(ctx, NULL, &secret_len) != 1) {
wpa_printf(MSG_ERROR,
"OpenSSL: EVP_PKEY_derive(1) failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
secret = wpabuf_alloc(secret_len);
if (!secret)
goto fail;
if (EVP_PKEY_derive(ctx, wpabuf_put(secret, secret_len),
&secret_len) != 1) {
wpa_printf(MSG_ERROR,
"OpenSSL: EVP_PKEY_derive(2) failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
done:
BN_free(x);
BN_free(y);
EC_KEY_free(eckey);
EC_POINT_free(pub);
EVP_PKEY_CTX_free(ctx);
EVP_PKEY_free(peerkey);
return secret;
fail:
wpabuf_free(secret);
secret = NULL;
goto done;
}
void crypto_ecdh_deinit(struct crypto_ecdh *ecdh)
{
if (ecdh) {
crypto_ec_deinit(ecdh->ec);
EVP_PKEY_free(ecdh->pkey);
os_free(ecdh);
}
}
#endif /* CONFIG_ECC */