| // Copyright 2016 Brian Smith. |
| // Portions Copyright (c) 2016, Google Inc. |
| // |
| // 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 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. |
| |
| use c; |
| use core; |
| use polyfill::slice::u32_from_le_u8; |
| |
| pub type Key = [u32; KEY_LEN_IN_BYTES / 4]; |
| |
| pub fn key_from_bytes(key_bytes: &[u8; KEY_LEN_IN_BYTES]) -> Key { |
| let mut key = [0u32; KEY_LEN_IN_BYTES / 4]; |
| for (key_u32, key_u8_4) in key.iter_mut().zip(key_bytes.chunks(4)) { |
| *key_u32 = u32_from_le_u8(slice_as_array_ref!(key_u8_4, 4).unwrap()); |
| } |
| key |
| } |
| |
| #[inline] |
| pub fn chacha20_xor_in_place(key: &Key, counter: &Counter, in_out: &mut [u8]) { |
| chacha20_xor_inner(key, counter, in_out.as_ptr(), in_out.len(), |
| in_out.as_mut_ptr()); |
| } |
| |
| pub fn chacha20_xor_overlapping(key: &Key, counter: &Counter, |
| in_out: &mut [u8], in_prefix_len: usize) { |
| // XXX: The x86 and at least one branch of the ARM assembly language |
| // code doesn't allow overlapping input and output unless they are |
| // exactly overlapping. TODO: Figure out which branch of the ARM code |
| // has this limitation and come up with a better solution. |
| // |
| // https://rt.openssl.org/Ticket/Display.html?id=4362 |
| let len = in_out.len() - in_prefix_len; |
| if cfg!(any(target_arch = "arm", target_arch = "x86")) && |
| in_prefix_len != 0 { |
| unsafe { |
| core::ptr::copy(in_out[in_prefix_len..].as_ptr(), |
| in_out.as_mut_ptr(), len); |
| } |
| chacha20_xor_in_place(key, &counter, &mut in_out[..len]); |
| } else { |
| chacha20_xor_inner(key, counter, in_out[in_prefix_len..].as_ptr(), |
| len, in_out.as_mut_ptr()); |
| } |
| } |
| |
| #[inline] |
| pub fn chacha20_xor_inner(key: &Key, counter: &Counter, input: *const u8, |
| in_out_len: usize, output: *mut u8) { |
| debug_assert!(core::mem::align_of_val(key) >= 4); |
| debug_assert!(core::mem::align_of_val(counter) >= 4); |
| unsafe { |
| GFp_ChaCha20_ctr32(output, input, in_out_len, key, counter); |
| } |
| } |
| |
| pub type Counter = [u32; 4]; |
| |
| #[inline] |
| pub fn make_counter(nonce: &[u8; NONCE_LEN], counter: u32) -> Counter { |
| [counter.to_le(), |
| u32_from_le_u8(slice_as_array_ref!(&nonce[0..4], 4).unwrap()), |
| u32_from_le_u8(slice_as_array_ref!(&nonce[4..8], 4).unwrap()), |
| u32_from_le_u8(slice_as_array_ref!(&nonce[8..12], 4).unwrap())] |
| } |
| |
| extern { |
| fn GFp_ChaCha20_ctr32(out: *mut u8, in_: *const u8, in_len: c::size_t, |
| key: &Key, counter: &Counter); |
| } |
| |
| pub const KEY_LEN_IN_BYTES: usize = 256 / 8; |
| |
| pub const NONCE_LEN: usize = 12; /* 96 bits */ |
| |
| #[cfg(test)] |
| mod tests { |
| use test; |
| use super::*; |
| use super::GFp_ChaCha20_ctr32; |
| |
| // This verifies the encryption functionality provided by ChaCha20_ctr32 |
| // is successful when either computed on disjoint input/output buffers, |
| // or on overlapping input/output buffers. On some branches of the 32-bit |
| // x86 and ARM code the in-place operation fails in some situations where |
| // the input/output buffers are not exactly overlapping. Such failures are |
| // dependent not only on the degree of overlapping but also the length of |
| // the data. `open()` works around that by moving the input data to the |
| // output location so that the buffers exactly overlap, for those targets. |
| // This test exists largely as a canary for detecting if/when that type of |
| // problem spreads to other platforms. |
| #[test] |
| pub fn chacha20_tests() { |
| test::from_file("src/chacha_tests.txt", |section, test_case| { |
| assert_eq!(section, ""); |
| |
| let key = test_case.consume_bytes("Key"); |
| let key = slice_as_array_ref!(&key, KEY_LEN_IN_BYTES)?; |
| let key = key_from_bytes(key); |
| |
| let ctr = test_case.consume_usize("Ctr"); |
| let nonce_bytes = test_case.consume_bytes("Nonce"); |
| let nonce = slice_as_array_ref!(&nonce_bytes, NONCE_LEN).unwrap(); |
| let ctr = make_counter(&nonce, ctr as u32); |
| let input = test_case.consume_bytes("Input"); |
| let output = test_case.consume_bytes("Output"); |
| |
| // Pre-allocate buffer for use in test_cases. |
| let mut in_out_buf = vec![0u8; input.len() + 276]; |
| |
| // Run the test case over all prefixes of the input because the |
| // behavior of ChaCha20 implementation changes dependent on the |
| // length of the input. |
| for len in 0..(input.len() + 1) { |
| chacha20_test_case_inner(&key, &ctr, &input[..len], |
| &output[..len], len, &mut in_out_buf); |
| } |
| |
| Ok(()) |
| }); |
| } |
| |
| fn chacha20_test_case_inner(key: &Key, ctr: &Counter, input: &[u8], |
| expected: &[u8], len: usize, |
| in_out_buf: &mut [u8]) { |
| // Straightforward encryption into disjoint buffers is computed |
| // correctly. |
| unsafe { |
| GFp_ChaCha20_ctr32(in_out_buf.as_mut_ptr(), input[..len].as_ptr(), |
| len, key, &ctr); |
| } |
| assert_eq!(&in_out_buf[..len], expected); |
| |
| // Do not test offset buffers for x86 and ARM architectures (see above |
| // for rationale). |
| let max_offset = |
| if cfg!(any(target_arch = "x86", target_arch = "arm")) { |
| 0 |
| } else { |
| 259 |
| }; |
| |
| // Check that in-place encryption works successfully when the pointers |
| // to the input/output buffers are (partially) overlapping. |
| for alignment in 0..16 { |
| for offset in 0..(max_offset + 1) { |
| in_out_buf[alignment+offset..][..len].copy_from_slice(input); |
| unsafe { |
| GFp_ChaCha20_ctr32(in_out_buf[alignment..].as_mut_ptr(), |
| in_out_buf[alignment + offset..].as_ptr(), |
| len, key, ctr); |
| assert_eq!(&in_out_buf[alignment..][..len], expected); |
| } |
| } |
| } |
| } |
| } |