unifdef BN_RECURSION

This removes a bunch of incomplete and scary code, which potentially leaks
secrets and is not constant time. A performance gain is achieved on arm64
for sizes that we care about, while a minimal decrease in performance is
noted for larger sizes on some other platforms.

While we will potentially reimplement Karatsuba (or Toom-Cook) at a later
date, it will be easier and safer to do it from a clean slate.

ok tb@

1 files changed, 1 insertions, 49 deletions

diff --git a/src/lib/libcrypto/bn/bn_lib.c b/src/lib/libcrypto/bn/bn_lib.c
index f25caa04af..89664fbb97 100644
--- a/src/lib/libcrypto/bn/bn_lib.c
+++ b/src/lib/libcrypto/bn/bn_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: bn_lib.c,v 1.81 2023/04/14 11:04:24 jsing Exp $ */
+/* $OpenBSD: bn_lib.c,v 1.82 2023/04/19 10:51:22 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -735,54 +735,6 @@ BN_set_negative(BIGNUM *bn, int neg)
         bn->neg = ~BN_is_zero(bn) & bn_ct_ne_zero(neg);
 }
 
-int
-bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
-{
-        int i;
-        BN_ULONG aa, bb;
-
-        aa = a[n - 1];
-        bb = b[n - 1];
-        if (aa != bb)
-                return ((aa > bb) ? 1 : -1);
-        for (i = n - 2; i >= 0; i--) {
-                aa = a[i];
-                bb = b[i];
-                if (aa != bb)
-                        return ((aa > bb) ? 1 : -1);
-        }
-        return (0);
-}
-
-/* Here follows a specialised variants of bn_cmp_words().  It has the
-   property of performing the operation on arrays of different sizes.
-   The sizes of those arrays is expressed through cl, which is the
-   common length ( basicall, min(len(a),len(b)) ), and dl, which is the
-   delta between the two lengths, calculated as len(a)-len(b).
-   All lengths are the number of BN_ULONGs...  */
-
-int
-bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b, int cl, int dl)
-{
-        int n, i;
-
-        n = cl - 1;
-
-        if (dl < 0) {
-                for (i = dl; i < 0; i++) {
-                        if (b[n - i] != 0)
-                                return -1; /* a < b */
-                }
-        }
-        if (dl > 0) {
-                for (i = dl; i > 0; i--) {
-                        if (a[n + i] != 0)
-                                return 1; /* a > b */
-                }
-        }
-        return bn_cmp_words(a, b, cl);
-}
-
 /*
  * Constant-time conditional swap of a and b.
  * a and b are swapped if condition is not 0.