crypto/
util.rs

1// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
2// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
3// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
4// option. This file may not be copied, modified, or distributed
5// except according to those terms.
6
7use libc;
8
9#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
10extern {
11    pub fn rust_crypto_util_supports_aesni() -> u32;
12}
13
14#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
15pub fn supports_aesni() -> bool {
16    unsafe {
17        rust_crypto_util_supports_aesni() != 0
18    }
19}
20
21extern {
22    pub fn rust_crypto_util_fixed_time_eq_asm(
23            lhsp: *const u8,
24            rhsp: *const u8,
25            count: libc::size_t) -> u32;
26    pub fn rust_crypto_util_secure_memset(
27            dst: *mut u8,
28            val: libc::uint8_t,
29            count: libc::size_t);
30}
31
32pub fn secure_memset(dst: &mut [u8], val: u8) {
33    unsafe {
34        rust_crypto_util_secure_memset(
35            dst.as_mut_ptr(),
36            val,
37            dst.len() as libc::size_t);
38    }
39}
40
41/// Compare two vectors using a fixed number of operations. If the two vectors are not of equal
42/// length, the function returns false immediately.
43pub fn fixed_time_eq(lhs: &[u8], rhs: &[u8]) -> bool {
44    if lhs.len() != rhs.len() {
45        false
46    } else {
47        let count = lhs.len() as libc::size_t;
48
49        unsafe {
50            let lhsp = lhs.get_unchecked(0);
51            let rhsp = rhs.get_unchecked(0);
52            rust_crypto_util_fixed_time_eq_asm(lhsp, rhsp, count) == 0
53        }
54    }
55}
56
57#[cfg(test)]
58mod test {
59    use util::fixed_time_eq;
60
61    #[test]
62    pub fn test_fixed_time_eq() {
63        let a = [0, 1, 2];
64        let b = [0, 1, 2];
65        let c = [0, 1, 9];
66        let d = [9, 1, 2];
67        let e = [2, 1, 0];
68        let f = [2, 2, 2];
69        let g = [0, 0, 0];
70
71        assert!(fixed_time_eq(&a, &a));
72        assert!(fixed_time_eq(&a, &b));
73
74        assert!(!fixed_time_eq(&a, &c));
75        assert!(!fixed_time_eq(&a, &d));
76        assert!(!fixed_time_eq(&a, &e));
77        assert!(!fixed_time_eq(&a, &f));
78        assert!(!fixed_time_eq(&a, &g));
79    }
80}
crypto/util.rs

crypto/
util.rs
