| // 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 { OPENSSL_memcmp(a.as_ptr(), b.as_ptr(), a.len()) }; |
| match result { |
| 0 => Ok(()), |
| _ => Err(error::Unspecified), |
| } |
| } |
| |
| prefixed_extern! { |
| fn OPENSSL_memcmp(a: *const u8, b: *const u8, len: c::size_t) -> c::size_t; |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use crate::{bssl, error}; |
| |
| #[test] |
| fn test_constant_time() -> Result<(), error::Unspecified> { |
| prefixed_extern! { |
| fn bssl_constant_time_test_main() -> bssl::Result; |
| } |
| Result::from(unsafe { bssl_constant_time_test_main() }) |
| } |
| } |