Files
aho_corasick
ansi_term
arrayvec
atty
backtrace
backtrace_sys
base64
bincode
bitflags
byteorder
bytes
c2_chacha
capnp
capnp_futures
capnp_rpc
cfg_if
chrono
clap
crossbeam_deque
crossbeam_epoch
crossbeam_queue
crossbeam_utils
ctrlc
daemon
failure
failure_derive
flexi_logger
fnv
futures
getrandom
glob
hid_io
api
device
module
protocol
hidapi
install_service
iovec
lazy_static
libc
lock_api
log
memchr
memoffset
mio
mio_uds
nanoid
net2
nix
nodrop
num_cpus
num_integer
num_traits
open
parking_lot
parking_lot_core
pem
ppv_lite86
proc_macro2
quote
rand
rand_chacha
rand_core
rand_hc
rand_isaac
rand_jitter
rand_os
rand_pcg
rand_xorshift
rcgen
regex
regex_syntax
remove_dir_all
ring
rustc_demangle
rustls
scoped_tls
scopeguard
sct
serde
slab
smallvec
spin
stream_cancel
strsim
syn
synstructure
tempfile
textwrap
thread_local
time
tokio
tokio_codec
tokio_core
tokio_current_thread
tokio_executor
tokio_fs
tokio_io
tokio_reactor
tokio_rustls
tokio_sync
tokio_tcp
tokio_threadpool
tokio_timer
tokio_udp
tokio_uds
unicode_width
unicode_xid
untrusted
vec_map
void
webpki
windows_service
x11
xcb
xkbcommon
yasna
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
// Copyright 2015-2016 Brian Smith.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

//! Constant-time operations.

use crate::{c, error};

/// Returns `Ok(())` if `a == b` and `Err(error::Unspecified)` otherwise.
/// The comparison of `a` and `b` is done in constant time with respect to the
/// contents of each, but NOT in constant time with respect to the lengths of
/// `a` and `b`.
pub fn verify_slices_are_equal(a: &[u8], b: &[u8]) -> Result<(), error::Unspecified> {
    if a.len() != b.len() {
        return Err(error::Unspecified);
    }
    let result = unsafe { GFp_memcmp(a.as_ptr(), b.as_ptr(), a.len()) };
    match result {
        0 => Ok(()),
        _ => Err(error::Unspecified),
    }
}

extern "C" {
    fn GFp_memcmp(a: *const u8, b: *const u8, len: c::size_t) -> c::int;
}

#[cfg(test)]
mod tests {
    use crate::{bssl, error};

    #[test]
    fn test_constant_time() -> Result<(), error::Unspecified> {
        extern "C" {
            fn bssl_constant_time_test_main() -> bssl::Result;
        }
        Result::from(unsafe { bssl_constant_time_test_main() })
    }
}