From af45e73f5c7de517c8376e3aba93bc12000c6065 Mon Sep 17 00:00:00 2001
From: sfluhrer <sfluhrer@cisco.com>
Date: Tue, 2 May 2023 09:16:17 -0400
Subject: [PATCH] Implement changes to hash-to-FORS-leaves transform

This is the change to the Sphincs+ definition by NIST
---
 ref/fors.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ref/fors.c b/ref/fors.c
index a4f2a199..3599e5b6 100644
--- a/ref/fors.c
+++ b/ref/fors.c
@@ -56,7 +56,7 @@ static void message_to_indices(uint32_t *indices, const unsigned char *m)
     for (i = 0; i < SPX_FORS_TREES; i++) {
         indices[i] = 0;
         for (j = 0; j < SPX_FORS_HEIGHT; j++) {
-            indices[i] ^= ((m[offset >> 3] >> (offset & 0x7)) & 0x1) << j;
+            indices[i] ^= ((m[offset >> 3] >> (~offset & 0x7)) & 0x1) << j;
             offset++;
         }
     }