ec25519-fhmqvc: don't check group order of peers' public keys

Skipping this check will significantly speed up startup with many peers. As we
now do embedded group order verification, an attacker can't gain anything from
small-subgroup attacks, so skipping the check isn't a security issue.

1 files changed, 1 insertions, 15 deletions

diff --git a/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c b/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c
index 97cdb3d..2303938 100644
--- a/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c
+++ b/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c
@@ -83,7 +83,7 @@ static fastd_protocol_key_t * protocol_read_key(const char *key) {
 
 	if (read_key(ret->key.u8, key)) {
 		if (ecc_25519_load_packed(&ret->unpacked, &ret->key.int256)) {
-			if (fastd_protocol_ec25519_fhmqvc_check_key(&ret->unpacked))
+			if (!ecc_25519_is_identity(&ret->unpacked))
 				return ret;
 		}
 	}
@@ -92,20 +92,6 @@ static fastd_protocol_key_t * protocol_read_key(const char *key) {
 	return NULL;
 }
 
-/** Checks if an ecc25519 work structure represents a valid curve point */
-bool fastd_protocol_ec25519_fhmqvc_check_key(const ecc_25519_work_t *key) {
-	ecc_25519_work_t work;
-
-	if (ecc_25519_is_identity(key))
-		return false;
-
-	ecc_25519_scalarmult(&work, &ecc_25519_gf_order, key);
-	if (!ecc_25519_is_identity(&work))
-		return false;
-
-	return true;
-}
-
 
 /** Checks if a peer is configured using our own key */
 static bool protocol_check_peer(const fastd_peer_t *peer) {