Use crypto.h API to implement ECDH in DPP.
Need to add a new init function in crypto.h to initialize an ECDH with
a given EC key.
Signed-off-by: Cedric Izoard <cedric.izoard@xxxxxxxxxxxx>
---
src/common/dpp_crypto.c | 80 +++++++++----------------------------
src/crypto/crypto.h | 33 ++++++++++-----
src/crypto/crypto_openssl.c | 28 +++++++++++++
3 files changed, 68 insertions(+), 73 deletions(-)
diff --git a/src/common/dpp_crypto.c b/src/common/dpp_crypto.c
index c1dffdb6f..756ba6164 100644
--- a/src/common/dpp_crypto.c
+++ b/src/common/dpp_crypto.c
@@ -610,84 +610,40 @@ int dpp_derive_bk_ke(struct dpp_authentication *auth)
int dpp_ecdh(struct crypto_ec_key *own, struct crypto_ec_key *peer, u8 *secret, size_t *secret_len)
{
- EVP_PKEY_CTX *ctx;
+ struct crypto_ecdh *ecdh;
+ struct wpabuf *secret_buf = NULL;
+ struct wpabuf *peer_pub = NULL;
int ret = -1;
- ERR_clear_error();
*secret_len = 0;
- ctx = EVP_PKEY_CTX_new((EVP_PKEY *)own, NULL);
- if (!ctx) {
- wpa_printf(MSG_ERROR, "DPP: EVP_PKEY_CTX_new failed: %s",
- ERR_error_string(ERR_get_error(), NULL));
+ ecdh = crypto_ecdh_init2(crypto_ec_key_group(own), own);
+ if (!ecdh) {
+ wpa_printf(MSG_ERROR, "DPP: crypto_ecdh_init2 failed");
return -1;
}
- if (EVP_PKEY_derive_init(ctx) != 1) {
- wpa_printf(MSG_ERROR, "DPP: EVP_PKEY_derive_init failed: %s",
- ERR_error_string(ERR_get_error(), NULL));
+ peer_pub = crypto_ec_key_get_pubkey_point(peer, 0);
+ if (!peer_pub) {
+ wpa_printf(MSG_ERROR, "DPP: crypto_ec_key_get_pubkey_point failed");
goto fail;
}
- if (EVP_PKEY_derive_set_peer(ctx, (EVP_PKEY *)peer) != 1) {
- wpa_printf(MSG_ERROR,
- "DPP: EVP_PKEY_derive_set_peet failed: %s",
- ERR_error_string(ERR_get_error(), NULL));
- goto fail;
- }
-
- if (EVP_PKEY_derive(ctx, NULL, secret_len) != 1) {
- wpa_printf(MSG_ERROR, "DPP: EVP_PKEY_derive(NULL) failed: %s",
- ERR_error_string(ERR_get_error(), NULL));
- goto fail;
- }
-
- if (*secret_len > DPP_MAX_SHARED_SECRET_LEN) {
- u8 buf[200];
- int level = *secret_len > 200 ? MSG_ERROR : MSG_DEBUG;
-
- /* It looks like OpenSSL can return unexpectedly large buffer
- * need for shared secret from EVP_PKEY_derive(NULL) in some
- * cases. For example, group 19 has shown cases where secret_len
- * is set to 72 even though the actual length ends up being
- * updated to 32 when EVP_PKEY_derive() is called with a buffer
- * for the value. Work around this by trying to fetch the value
- * and continue if it is within supported range even when the
- * initial buffer need is claimed to be larger. */
- wpa_printf(level,
- "DPP: Unexpected secret_len=%d from EVP_PKEY_derive()",
- (int) *secret_len);
- if (*secret_len > 200)
- goto fail;
- if (EVP_PKEY_derive(ctx, buf, secret_len) != 1) {
- wpa_printf(MSG_ERROR, "DPP: EVP_PKEY_derive failed: %s",
- ERR_error_string(ERR_get_error(), NULL));
- goto fail;
- }
- if (*secret_len > DPP_MAX_SHARED_SECRET_LEN) {
- wpa_printf(MSG_ERROR,
- "DPP: Unexpected secret_len=%d from EVP_PKEY_derive()",
- (int) *secret_len);
- goto fail;
- }
- wpa_hexdump_key(MSG_DEBUG, "DPP: Unexpected secret_len change",
- buf, *secret_len);
- os_memcpy(secret, buf, *secret_len);
- forced_memzero(buf, sizeof(buf));
- goto done;
- }
-
- if (EVP_PKEY_derive(ctx, secret, secret_len) != 1) {
- wpa_printf(MSG_ERROR, "DPP: EVP_PKEY_derive failed: %s",
- ERR_error_string(ERR_get_error(), NULL));
+ secret_buf = crypto_ecdh_set_peerkey(ecdh, 1, wpabuf_head(peer_pub),
+ wpabuf_len(peer_pub));
+ if (!secret_buf) {
+ wpa_printf(MSG_ERROR, "DPP: crypto_ecdh_set_peerkey failed");
goto fail;
}
-done:
+ *secret_len = wpabuf_len(secret_buf);
+ os_memcpy(secret, wpabuf_head(secret_buf), wpabuf_len(secret_buf));
ret = 0;
fail:
- EVP_PKEY_CTX_free(ctx);
+ wpabuf_clear_free(secret_buf);
+ wpabuf_clear_free(peer_pub);
+ crypto_ecdh_deinit(ecdh);
return ret;
}
diff --git a/src/crypto/crypto.h b/src/crypto/crypto.h
index 7c2bc82e2..c87cbcbe8 100644
--- a/src/crypto/crypto.h
+++ b/src/crypto/crypto.h
@@ -930,6 +930,14 @@ void crypto_ec_point_debug_print(const struct crypto_ec *e,
const struct crypto_ec_point *p,
const char *title);
+/**
+ * struct crypto_ec_key - Elliptic Curve Key pair
+ *
+ * Internal data structure for EC Key pair. The contents is specific to the used
+ * crypto library.
+ */
+struct crypto_ec_key;
+
/**
* struct crypto_ecdh - Elliptic Curve Diffie–Hellman context
*
@@ -942,13 +950,24 @@ struct crypto_ecdh;
* crypto_ecdh_init - Initialize elliptic curve diffie–hellman context
* @group: Identifying number for the ECC group (IANA "Group Description"
* attribute registrty for RFC 2409)
+ * This function generates ephemeral key pair.
* Returns: Pointer to ECDH context or %NULL on failure
*/
struct crypto_ecdh * crypto_ecdh_init(int group);
+/**
+ * crypto_ecdh_init2 - Initialize elliptic curve diffie–hellman context with
+ * given EC key
+ * @group: Identifying number for the ECC group (IANA "Group Description"
+ * attribute registrty for RFC 2409)
+ * @own_key: Our own EC Key.
+ * Returns: Pointer to ECDH context or %NULL on failure
+ */
+struct crypto_ecdh * crypto_ecdh_init2(int group, struct crypto_ec_key *own_key);
+
/**
* crypto_ecdh_get_pubkey - Retrieve Public from ECDH context
- * @ecdh: ECDH context from crypto_ecdh_init()
+ * @ecdh: ECDH context from crypto_ecdh_init() or crypto_ecdh_init2()
* @inc_y: Whether public key should include y coordinate (explicit form)
* or not (compressed form)
* Returns: Binary data f the public key or %NULL on failure
@@ -957,7 +976,7 @@ struct wpabuf * crypto_ecdh_get_pubkey(struct crypto_ecdh *ecdh, int inc_y);
/**
* crypto_ecdh_set_peerkey - Compute ECDH secret
- * @ecdh: ECDH context from crypto_ecdh_init()
+ * @ecdh: ECDH context from crypto_ecdh_init() or crypto_ecdh_init2()
* @inc_y: Whether Peer's public key includes y coordinate (explicit form)
* or not (compressed form)
* @key: Binary data of the Peer's public key
@@ -969,7 +988,7 @@ struct wpabuf * crypto_ecdh_set_peerkey(struct crypto_ecdh *ecdh, int inc_y,
/**
* crypto_ecdh_deinit - Free ECDH context
- * @ecdh: ECDH context from crypto_ecdh_init()
+ * @ecdh: ECDH context from crypto_ecdh_init() or crypto_ecdh_init2()
*/
void crypto_ecdh_deinit(struct crypto_ecdh *ecdh);
@@ -980,14 +999,6 @@ void crypto_ecdh_deinit(struct crypto_ecdh *ecdh);
*/
size_t crypto_ecdh_prime_len(struct crypto_ecdh *ecdh);
-/**
- * struct crypto_ec_key - Elliptic Curve Key pair
- *
- * Internal data structure for EC Key pair. The contents is specific to the used
- * crypto library.
- */
-struct crypto_ec_key;
-
/**
* crypto_ec_key_parse_priv - Initialize EC Key pair from ECPrivateKey ASN.1
* @der: DER encoding of ASN.1 ECPrivateKey
diff --git a/src/crypto/crypto_openssl.c b/src/crypto/crypto_openssl.c
index 308bab908..bca512f6c 100644
--- a/src/crypto/crypto_openssl.c
+++ b/src/crypto/crypto_openssl.c
@@ -2042,6 +2042,34 @@ fail:
}
+struct crypto_ecdh * crypto_ecdh_init2(int group, struct crypto_ec_key *own_key)
+{
+ struct crypto_ecdh *ecdh;
+
+ ecdh = os_zalloc(sizeof(*ecdh));
+ if (!ecdh)
+ goto fail;
+
+ ecdh->ec = crypto_ec_init(group);
+ if (!ecdh->ec)
+ goto fail;
+
+ ecdh->pkey = EVP_PKEY_new();
+ if (!ecdh->pkey ||
+ EVP_PKEY_assign_EC_KEY(ecdh->pkey,
+ EVP_PKEY_get1_EC_KEY((EVP_PKEY *)own_key)) != 1) {
+ goto fail;
+ }
+
+done:
+ 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;
--
2.17.0
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