From e70e34d857d4003199bcb5d3b52ca8102ccc1b98 Mon Sep 17 00:00:00 2001
From: Tomas Mraz <tomas@openssl.org>
Date: Mon, 5 Aug 2024 17:54:14 +0200
Subject: [PATCH] dh_kmgmt.c: Avoid expensive public key validation for known
 safe-prime groups
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The partial validation is fully sufficient to check the key validity.

Thanks to Szilárd Pfeiffer for reporting the issue.

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/25088)
---
 providers/implementations/keymgmt/dh_kmgmt.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/providers/implementations/keymgmt/dh_kmgmt.c b/providers/implementations/keymgmt/dh_kmgmt.c
index 82c3093b122c2..ebdce767102ee 100644
--- a/providers/implementations/keymgmt/dh_kmgmt.c
+++ b/providers/implementations/keymgmt/dh_kmgmt.c
@@ -388,9 +388,11 @@ static int dh_validate_public(const DH *dh, int checktype)
     if (pub_key == NULL)
         return 0;
 
-    /* The partial test is only valid for named group's with q = (p - 1) / 2 */
-    if (checktype == OSSL_KEYMGMT_VALIDATE_QUICK_CHECK
-        && ossl_dh_is_named_safe_prime_group(dh))
+    /*
+     * The partial test is only valid for named group's with q = (p - 1) / 2
+     * but for that case it is also fully sufficient to check the key validity.
+     */
+    if (ossl_dh_is_named_safe_prime_group(dh))
         return ossl_dh_check_pub_key_partial(dh, pub_key, &res);
 
     return DH_check_pub_key_ex(dh, pub_key);