From 26148282e67a6de0afcaa418c9730ccd5836b234 Mon Sep 17 00:00:00 2001
From: Pol Henarejos <pol.henarejos@cttc.es>
Date: Fri, 18 Aug 2023 13:07:06 +0200
Subject: [PATCH] Fix credential creation for ES512.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
---
 src/fido/fido.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/fido/fido.c b/src/fido/fido.c
index abb0bf9..885e58b 100644
--- a/src/fido/fido.c
+++ b/src/fido/fido.c
@@ -262,6 +262,9 @@ int derive_key(const uint8_t *app_id,
         if (cinfo == NULL) {
             return 1;
         }
+        if (cinfo->bit_size % 8 != 0) {
+            outk[0] >>= 8 - (cinfo->bit_size % 8);
+        }
         r = mbedtls_ecp_read_key(curve, key, outk, ceil((float) cinfo->bit_size / 8));
         mbedtls_platform_zeroize(outk, sizeof(outk));
         if (r != 0) {