From a1db7ec1eaacffbc1564ca7f84ec90d4d4059573 Mon Sep 17 00:00:00 2001
From: Pol Henarejos <pol.henarejos@cttc.es>
Date: Thu, 8 Sep 2022 13:51:15 +0200
Subject: [PATCH] Add length check.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
---
 src/fido/cmd_register.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/fido/cmd_register.c b/src/fido/cmd_register.c
index 604ce94..38a3172 100644
--- a/src/fido/cmd_register.c
+++ b/src/fido/cmd_register.c
@@ -30,6 +30,8 @@ int cmd_register() {
     resp->keyHandleLen = KEY_HANDLE_LEN;
     if (scan_files() != CCID_OK)
         return SW_EXEC_ERROR();
+    if (apdu.nc != U2F_APPID_SIZE + U2F_CHAL_SIZE)
+        return SW_WRONG_LENGTH();
     if (wait_button_pressed() == true)
         return SW_CONDITIONS_NOT_SATISFIED();
     mbedtls_ecdsa_context key;