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DPP: Remove direct call to OpenSSL in dpp_test_gen_invalid_key()

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Instead of generating EC point with random coordinates, generate a
valid EC point and then corrupt the coordinates after exporting them
in binary format.

Signed-off-by: Cedric Izoard <cedric.izoard@ceva-dsp.com>
This commit is contained in:
Cedric Izoard 2021-06-28 18:25:35 +02:00 committed by Jouni Malinen
parent c88b7fcaef
commit 87f2fb8863
2 changed files with 28 additions and 61 deletions
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88
src/common/dpp_crypto.c
View file

@ -297,20 +297,6 @@ int dpp_pbkdf2(size_t hash_len, const u8 *password, size_t password_len,
#endif /* CONFIG_DPP2 */
int dpp_bn2bin_pad(const BIGNUM *bn, u8 *pos, size_t len)
{
int num_bytes, offset;
num_bytes = BN_num_bytes(bn);
if ((size_t) num_bytes > len)
return -1;
offset = len - num_bytes;
os_memset(pos, 0, offset);
BN_bn2bin(bn, pos + offset);
return 0;
}
struct crypto_ec_key * dpp_set_pubkey_point(struct crypto_ec_key *group_key,
const u8 *buf, size_t len)
{
@ -2705,64 +2691,46 @@ fail:
int dpp_test_gen_invalid_key(struct wpabuf *msg,
const struct dpp_curve_params *curve)
{
BN_CTX *ctx;
BIGNUM *x, *y;
struct crypto_ec *ec;
struct crypto_ec_key *key = NULL;
const struct crypto_ec_point *pub_key;
struct crypto_ec_point *p = NULL;
u8 *x, *y;
int ret = -1;
EC_GROUP *group;
EC_POINT *point;
group = EC_GROUP_new_by_curve_name(OBJ_txt2nid(curve->name));
if (!group)
return -1;
ctx = BN_CTX_new();
point = EC_POINT_new(group);
x = BN_new();
y = BN_new();
if (!ctx || !point || !x || !y)
ec = crypto_ec_init(curve->ike_group);
x = wpabuf_put(msg, curve->prime_len);
y = wpabuf_put(msg, curve->prime_len);
if (!ec)
goto fail;
if (BN_rand(x, curve->prime_len * 8, 0, 0) != 1)
retry:
/* Generate valid key pair */
key = crypto_ec_key_gen(curve->ike_group);
if (!key)
goto fail;
/* Generate a random y coordinate that results in a point that is not
* on the curve. */
for (;;) {
if (BN_rand(y, curve->prime_len * 8, 0, 0) != 1)
goto fail;
/* Retrieve public key coordinates */
pub_key = crypto_ec_key_get_public_key(key);
if (!pub_key)
goto fail;
if (EC_POINT_set_affine_coordinates_GFp(group, point, x, y,
ctx) != 1) {
#if OPENSSL_VERSION_NUMBER >= 0x10100000L || defined(OPENSSL_IS_BORINGSSL)
/* Unlike older OpenSSL versions, OpenSSL 1.1.1 and BoringSSL
* return an error from EC_POINT_set_affine_coordinates_GFp()
* when the point is not on the curve. */
break;
#else /* >=1.1.0 or OPENSSL_IS_BORINGSSL */
goto fail;
#endif /* >= 1.1.0 or OPENSSL_IS_BORINGSSL */
}
crypto_ec_point_to_bin(ec, pub_key, x, y);
if (!EC_POINT_is_on_curve(group, point, ctx))
break;
/* And corrupt them */
y[curve->prime_len - 1] ^= 0x01;
p = crypto_ec_point_from_bin(ec, x);
if (p && crypto_ec_point_is_on_curve(ec, p)) {
crypto_ec_point_deinit(p, 0);
p = NULL;
goto retry;
}
if (dpp_bn2bin_pad(x, wpabuf_put(msg, curve->prime_len),
curve->prime_len) < 0 ||
dpp_bn2bin_pad(y, wpabuf_put(msg, curve->prime_len),
curve->prime_len) < 0)
goto fail;
ret = 0;
fail:
if (ret < 0)
wpa_printf(MSG_INFO, "DPP: Failed to generate invalid key");
BN_free(x);
BN_free(y);
EC_POINT_free(point);
BN_CTX_free(ctx);
EC_GROUP_free(group);
crypto_ec_point_deinit(p, 0);
crypto_ec_key_deinit(key);
crypto_ec_deinit(ec);
return ret;
}

1
src/common/dpp_i.h
View file

@ -79,7 +79,6 @@ int dpp_bi_pubkey_hash(struct dpp_bootstrap_info *bi,
const u8 *data, size_t data_len);
struct crypto_ec_key * dpp_set_pubkey_point(struct crypto_ec_key *group_key,
const u8 *buf, size_t len);
int dpp_bn2bin_pad(const BIGNUM *bn, u8 *pos, size_t len);
int dpp_hkdf_expand(size_t hash_len, const u8 *secret, size_t secret_len,
const char *label, u8 *out, size_t outlen);
int dpp_hmac_vector(size_t hash_len, const u8 *key, size_t key_len,