From f9ca6e850165600356636f6c853cbd9942a690dd Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Sat, 28 Jun 2003 14:10:06 +0000
Subject: [PATCH] bignum_mod_short shouldn't be depending on a fixed place
 value in the bignum data! This wasn't actually causing puttygen-zero-div (its
 unwarranted assumption was still correct under Windows) but it would have
 caused the same symptoms under Unix when I got round to porting PuTTYgen.

[originally from svn r3315]
---
 sshbn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sshbn.c b/sshbn.c
index 37422271..2d8359e3 100644
--- a/sshbn.c
+++ b/sshbn.c
@@ -814,7 +814,7 @@ unsigned short bignum_mod_short(Bignum number, unsigned short modulus)
     r = 0;
     mod = modulus;
     for (i = number[0]; i > 0; i--)
-	r = (r * 65536 + number[i]) % mod;
+	r = (r * (BIGNUM_TOP_BIT % mod) * 2 + number[i] % mod) % mod;
     return (unsigned short) r;
 }