diff options
| author | riastradh <riastradh@NetBSD.org> | 2013-06-24 04:21:19 +0000 |
|---|---|---|
| committer | riastradh <riastradh@NetBSD.org> | 2013-06-24 04:21:19 +0000 |
| commit | adfdcceb8aad478bc3c5692fb3aff045c0c8ef37 (patch) | |
| tree | ee62fd1d002750ee339715e953885019cf401475 /lib/libc/string/consttime_memequal.3 | |
| parent | 8fcb059d64019ef3a03b90cb11f6c6d47aeeb6b9 (diff) | |
Replace consttime_bcmp/explicit_bzero by consttime_memequal/explicit_memset.
consttime_memequal is the same as the old consttime_bcmp.
explicit_memset is to memset as explicit_bzero was to bcmp.
Passes amd64 release and i386/ALL, but I'm sure I missed some spots,
so please let me know.
Diffstat (limited to 'lib/libc/string/consttime_memequal.3')
| -rw-r--r-- | lib/libc/string/consttime_memequal.3 | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/lib/libc/string/consttime_memequal.3 b/lib/libc/string/consttime_memequal.3 new file mode 100644 index 00000000000..2f71503b777 --- /dev/null +++ b/lib/libc/string/consttime_memequal.3 @@ -0,0 +1,88 @@ +.\" $NetBSD: consttime_memequal.3,v 1.1 2013/06/24 04:21:20 riastradh Exp $ +.\" +.\" Copyright (c) 2013 The NetBSD Foundation, Inc. +.\" All rights reserved. +.\" +.\" This documentation is derived from text contributed to The NetBSD +.\" Foundation by Taylor R. Campbell. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS +.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED +.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS +.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN +.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +.\" POSSIBILITY OF SUCH DAMAGE. +.\" +.Dd June 23, 2013 +.Dt CONSTTIME_MEMEQUAL 3 +.Os +.Sh NAME +.Nm consttime_memequal +.Nd compare byte strings for equality without timing leaks +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In string.h +.Ft int +.Fn consttime_memequal "void *b1" "void *b2" "size_t len" +.Sh DESCRIPTION +The +.Fn consttime_memequal +function compares +.Fa len +bytes of memory at +.Fa b1 +and +.Fa b2 +for equality, returning zero if they are identical and nonzero +otherwise. +.Pp +The time taken by +.Fn consttime_memequal +depends on +.Fa len , +but not on the data at +.Fa b1 +or +.Fa b2 . +Thus, +.Fn consttime_memequal +is appropriate for comparing cryptographic secrets, hashes, message +authentication codes, etc., without leaking information about them +through a timing side channel. +In crypto literature, +.Fn consttime_memequal +is said to take +.Sq constant time , +meaning time that does not vary depending on the data it processes. +.Pp +Note that unlike +.Xr memcmp 3 , +.Fn consttime_memequal +does not return a lexicographic ordering on the data at +.Fa b1 +and +.Fa b2 ; +it tells only whether they are equal. +.Sh SEE ALSO +.Xr explicit_memset 3 , +.Xr memcmp 3 +.Sh HISTORY +The +.Fn consttime_memequal +function appeared in +.Nx 7.0 . |
