Mercurial > dropbear

annotate libtomcrypt/src/misc/mem_neq.c @ 1780:b5aedadc0008

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
fuzzing - Set postauth user to root since that's what it runs as
author Matt Johnston <matt@ucc.asn.au>
date Tue, 17 Nov 2020 19:28:11 +0800
parents 6dba84798cd5
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
1471
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
2 *
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
3 * LibTomCrypt is a library that provides various cryptographic
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
4 * algorithms in a highly modular and flexible manner.
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
5 *
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
6 * The library is free for all purposes without any express
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
7 * guarantee it works.
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
8 */
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
9 #include "tomcrypt.h"
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
10
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
11 /**
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
12 @file mem_neq.c
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
13 Compare two blocks of memory for inequality in constant time.
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
14 Steffen Jaeckel
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
15 */
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
16
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
17 /**
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
18 Compare two blocks of memory for inequality in constant time.
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
19
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
20 The usage is similar to that of standard memcmp, but you can only test
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
21 if the memory is equal or not - you can not determine by how much the
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
22 first different byte differs.
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
23
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
24 This function shall be used to compare results of cryptographic
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
25 operations where inequality means most likely usage of a wrong key.
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
26 The execution time has therefore to be constant as otherwise
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
27 timing attacks could be possible.
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
28
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
29 @param a The first memory region
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
30 @param b The second memory region
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
31 @param len The length of the area to compare (octets)
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
32
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
33 @return 0 when a and b are equal for len bytes, 1 they are not equal.
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
34 */
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
35 int mem_neq(const void *a, const void *b, size_t len)
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
36 {
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
37 unsigned char ret = 0;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
38 const unsigned char* pa;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
39 const unsigned char* pb;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
40
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
41 LTC_ARGCHK(a != NULL);
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
42 LTC_ARGCHK(b != NULL);
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
43
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
44 pa = a;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
45 pb = b;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
46
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
47 while (len-- > 0) {
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
48 ret |= *pa ^ *pb;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
49 ++pa;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
50 ++pb;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
51 }
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
52
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
53 ret |= ret >> 4;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
54 ret |= ret >> 2;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
55 ret |= ret >> 1;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
56 ret &= 1;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
57
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
58 return ret;
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
59 }
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
60
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
61 /* ref: $Format:%D$ */
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
62 /* git commit: $Format:%H$ */
6dba84798cd5 Update to libtomcrypt 1.18.1, merged with Dropbear changes
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
63 /* commit time: $Format:%ai$ */