Split BN_mod_sqr_reciprocal() out of BN_mod_mul_reciprocal()

There's no need for BN_mod_mul_reciprocal() to have this complication.
The caller knows when x == y, so place the burden on the caller. This
simplifies both the caller side and the implementation in bn_recp.c.

ok jsing

1 files changed, 4 insertions, 4 deletions

diff --git a/src/lib/libcrypto/bn/bn_exp.c b/src/lib/libcrypto/bn/bn_exp.c
index 8ff518e938..129c12495c 100644
--- a/src/lib/libcrypto/bn/bn_exp.c
+++ b/src/lib/libcrypto/bn/bn_exp.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_exp.c,v 1.54 2025/01/21 15:44:22 tb Exp $ */
+/* $OpenBSD: bn_exp.c,v 1.55 2025/01/22 10:08:10 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1023,7 +1023,7 @@ BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
 
         window = BN_window_bits_for_exponent_size(bits);
         if (window > 1) {
-                if (!BN_mod_mul_reciprocal(aa, val[0], val[0], recp, ctx))
+                if (!BN_mod_sqr_reciprocal(aa, val[0], recp, ctx))
                         goto err;
                 j = 1 << (window - 1);
                 for (i = 1; i < j; i++) {
@@ -1047,7 +1047,7 @@ BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
         for (;;) {
                 if (BN_is_bit_set(q, wstart) == 0) {
                         if (!start)
-                                if (!BN_mod_mul_reciprocal(r, r, r, recp, ctx))
+                                if (!BN_mod_sqr_reciprocal(r, r, recp, ctx))
                                         goto err;
                         if (wstart == 0)
                                 break;
@@ -1076,7 +1076,7 @@ BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
                 /* add the 'bytes above' */
                 if (!start)
                         for (i = 0; i < j; i++) {
-                                if (!BN_mod_mul_reciprocal(r, r, r, recp, ctx))
+                                if (!BN_mod_sqr_reciprocal(r, r, recp, ctx))
                                         goto err;
                         }