mirror of
https://abf.rosa.ru/djam/openssl.git
synced 2025-02-23 16:22:50 +00:00
89 lines
3 KiB
Diff
89 lines
3 KiB
Diff
From 47061af1062e36b87242810f7f5279ee7240b9e4 Mon Sep 17 00:00:00 2001
|
|
From: Andy Polyakov <appro@openssl.org>
|
|
Date: Fri, 8 Feb 2013 16:59:26 +0100
|
|
Subject: [PATCH] s3_cbc.c: get rid of expensive divisions [from master].
|
|
(cherry picked from commit
|
|
e9baceab5a385e570706ca98dec768b2d89d1ac6)
|
|
|
|
---
|
|
ssl/s3_cbc.c | 35 +++++++++++++++++++++--------------
|
|
1 file changed, 21 insertions(+), 14 deletions(-)
|
|
|
|
diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c
|
|
index 0f60507..f8d8ee8 100644
|
|
--- a/ssl/s3_cbc.c
|
|
+++ b/ssl/s3_cbc.c
|
|
@@ -76,6 +76,13 @@
|
|
#define DUPLICATE_MSB_TO_ALL(x) ( (unsigned)( (int)(x) >> (sizeof(int)*8-1) ) )
|
|
#define DUPLICATE_MSB_TO_ALL_8(x) ((unsigned char)(DUPLICATE_MSB_TO_ALL(x)))
|
|
|
|
+/* constant_time_lt returns 0xff if a<b and 0x00 otherwise. */
|
|
+static unsigned constant_time_lt(unsigned a, unsigned b)
|
|
+ {
|
|
+ a -= b;
|
|
+ return DUPLICATE_MSB_TO_ALL(a);
|
|
+ }
|
|
+
|
|
/* constant_time_ge returns 0xff if a>=b and 0x00 otherwise. */
|
|
static unsigned constant_time_ge(unsigned a, unsigned b)
|
|
{
|
|
@@ -84,7 +91,7 @@ static unsigned constant_time_ge(unsigned a, unsigned b)
|
|
}
|
|
|
|
/* constant_time_eq_8 returns 0xff if a==b and 0x00 otherwise. */
|
|
-static unsigned char constant_time_eq_8(unsigned char a, unsigned char b)
|
|
+static unsigned char constant_time_eq_8(unsigned a, unsigned b)
|
|
{
|
|
unsigned c = a ^ b;
|
|
c--;
|
|
@@ -288,16 +295,13 @@ void ssl3_cbc_copy_mac(unsigned char* out,
|
|
rotate_offset = (div_spoiler + mac_start - scan_start) % md_size;
|
|
|
|
memset(rotated_mac, 0, md_size);
|
|
- for (i = scan_start; i < rec->orig_len;)
|
|
+ for (i = scan_start, j = 0; i < rec->orig_len; i++)
|
|
{
|
|
- for (j = 0; j < md_size && i < rec->orig_len; i++, j++)
|
|
- {
|
|
- unsigned char mac_started = constant_time_ge(i, mac_start);
|
|
- unsigned char mac_ended = constant_time_ge(i, mac_end);
|
|
- unsigned char b = 0;
|
|
- b = rec->data[i];
|
|
- rotated_mac[j] |= b & mac_started & ~mac_ended;
|
|
- }
|
|
+ unsigned char mac_started = constant_time_ge(i, mac_start);
|
|
+ unsigned char mac_ended = constant_time_ge(i, mac_end);
|
|
+ unsigned char b = rec->data[i];
|
|
+ rotated_mac[j++] |= b & mac_started & ~mac_ended;
|
|
+ j &= constant_time_lt(j,md_size);
|
|
}
|
|
|
|
/* Now rotate the MAC */
|
|
@@ -305,16 +309,19 @@ void ssl3_cbc_copy_mac(unsigned char* out,
|
|
j = 0;
|
|
for (i = 0; i < md_size; i++)
|
|
{
|
|
- unsigned char offset = (div_spoiler + rotate_offset + i) % md_size;
|
|
- out[j++] = rotated_mac[offset];
|
|
+ out[j++] = rotated_mac[rotate_offset++];
|
|
+ rotate_offset &= constant_time_lt(rotate_offset,md_size);
|
|
}
|
|
#else
|
|
memset(out, 0, md_size);
|
|
+ rotate_offset = md_size - rotate_offset;
|
|
+ rotate_offset &= constant_time_lt(rotate_offset,md_size);
|
|
for (i = 0; i < md_size; i++)
|
|
{
|
|
- unsigned char offset = (div_spoiler + md_size - rotate_offset + i) % md_size;
|
|
for (j = 0; j < md_size; j++)
|
|
- out[j] |= rotated_mac[i] & constant_time_eq_8(j, offset);
|
|
+ out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset);
|
|
+ rotate_offset++;
|
|
+ rotate_offset &= constant_time_lt(rotate_offset,md_size);
|
|
}
|
|
#endif
|
|
}
|
|
--
|
|
1.7.9.5
|
|
|
|
|