bn_recp: Avoid complication for negative moduli

Instead of doing a weird dance, set the sign on N in BN_RECP_CTX_create().
Since we're not exposing a general purpose calculator API, we can simplify.

ok jsing

1 files changed, 2 insertions, 1 deletions

diff --git a/src/lib/libcrypto/bn/bn_recp.c b/src/lib/libcrypto/bn/bn_recp.c
index 6277b06dab..8f917e95db 100644
--- a/src/lib/libcrypto/bn/bn_recp.c
+++ b/src/lib/libcrypto/bn/bn_recp.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_recp.c,v 1.29 2025/01/22 10:12:01 tb Exp $ */
+/* $OpenBSD: bn_recp.c,v 1.30 2025/01/22 12:53:16 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -79,6 +79,7 @@ BN_RECP_CTX_create(const BIGNUM *N)
 
         if ((recp->N = BN_dup(N)) == NULL)
                 goto err;
+        BN_set_negative(recp->N, 0);
         recp->num_bits = BN_num_bits(recp->N);
 
         if ((recp->Nr = BN_new()) == NULL)