ring/aead/
poly1305.rs

1// Copyright 2015-2016 Brian Smith.
2// Portions Copyright (c) 2014, 2015, Google Inc.
3//
4// Permission to use, copy, modify, and/or distribute this software for any
5// purpose with or without fee is hereby granted, provided that the above
6// copyright notice and this permission notice appear in all copies.
7//
8// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
9// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
11// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
13// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
14// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15
16// TODO: enforce maximum input length.
17
18use super::{Tag, TAG_LEN};
19use crate::{c, cpu};
20
21/// A Poly1305 key.
22pub(super) struct Key {
23    key_and_nonce: [u8; KEY_LEN],
24}
25
26pub(super) const BLOCK_LEN: usize = 16;
27pub(super) const KEY_LEN: usize = 2 * BLOCK_LEN;
28
29impl Key {
30    #[inline]
31    pub(super) fn new(key_and_nonce: [u8; KEY_LEN]) -> Self {
32        Self { key_and_nonce }
33    }
34}
35
36pub struct Context {
37    state: poly1305_state,
38    #[allow(dead_code)]
39    cpu_features: cpu::Features,
40}
41
42// Keep in sync with `poly1305_state` in ring-core/poly1305.h.
43//
44// The C code, in particular the way the `poly1305_aligned_state` functions
45// are used, is only correct when the state buffer is 64-byte aligned.
46#[repr(C, align(64))]
47struct poly1305_state([u8; OPAQUE_LEN]);
48const OPAQUE_LEN: usize = 512;
49
50// Abstracts the dispatching logic that chooses the NEON implementation if and
51// only if it would work.
52macro_rules! dispatch {
53    ( $features:expr =>
54      ( $f:ident | $neon_f:ident )
55      ( $( $p:ident : $t:ty ),+ )
56      ( $( $a:expr ),+ ) ) => {
57        match () {
58            // Apple's 32-bit ARM ABI is incompatible with the assembly code.
59            #[cfg(all(target_arch = "arm", not(target_vendor = "apple")))]
60            () if cpu::arm::NEON.available($features) => {
61                prefixed_extern! {
62                    fn $neon_f( $( $p : $t ),+ );
63                }
64                unsafe { $neon_f( $( $a ),+ ) }
65            }
66            () => {
67                prefixed_extern! {
68                    fn $f( $( $p : $t ),+ );
69                }
70                unsafe { $f( $( $a ),+ ) }
71            }
72        }
73    }
74}
75
76impl Context {
77    #[inline]
78    pub(super) fn from_key(Key { key_and_nonce }: Key, cpu_features: cpu::Features) -> Self {
79        let mut ctx = Self {
80            state: poly1305_state([0u8; OPAQUE_LEN]),
81            cpu_features,
82        };
83
84        dispatch!(
85            cpu_features =>
86            (CRYPTO_poly1305_init | CRYPTO_poly1305_init_neon)
87            (statep: &mut poly1305_state, key: &[u8; KEY_LEN])
88            (&mut ctx.state, &key_and_nonce));
89
90        ctx
91    }
92
93    #[inline(always)]
94    pub fn update(&mut self, input: &[u8]) {
95        dispatch!(
96            self.cpu_features =>
97            (CRYPTO_poly1305_update | CRYPTO_poly1305_update_neon)
98            (statep: &mut poly1305_state, input: *const u8, in_len: c::size_t)
99            (&mut self.state, input.as_ptr(), input.len()));
100    }
101
102    pub(super) fn finish(mut self) -> Tag {
103        let mut tag = Tag([0u8; TAG_LEN]);
104        dispatch!(
105            self.cpu_features =>
106            (CRYPTO_poly1305_finish | CRYPTO_poly1305_finish_neon)
107            (statep: &mut poly1305_state, mac: &mut [u8; TAG_LEN])
108            (&mut self.state, &mut tag.0));
109        tag
110    }
111}
112
113/// Implements the original, non-IETF padding semantics.
114///
115/// This is used by chacha20_poly1305_openssh and the standalone
116/// poly1305 test vectors.
117pub(super) fn sign(key: Key, input: &[u8], cpu_features: cpu::Features) -> Tag {
118    let mut ctx = Context::from_key(key, cpu_features);
119    ctx.update(input);
120    ctx.finish()
121}
122
123#[cfg(test)]
124mod tests {
125    use super::*;
126    use crate::test;
127
128    // Adapted from BoringSSL's crypto/poly1305/poly1305_test.cc.
129    #[test]
130    pub fn test_poly1305() {
131        let cpu_features = cpu::features();
132        test::run(test_file!("poly1305_test.txt"), |section, test_case| {
133            assert_eq!(section, "");
134            let key = test_case.consume_bytes("Key");
135            let key: &[u8; KEY_LEN] = key.as_slice().try_into().unwrap();
136            let input = test_case.consume_bytes("Input");
137            let expected_mac = test_case.consume_bytes("MAC");
138            let key = Key::new(*key);
139            let Tag(actual_mac) = sign(key, &input, cpu_features);
140            assert_eq!(expected_mac, actual_mac.as_ref());
141
142            Ok(())
143        })
144    }
145}
ring/aead/poly1305.rs

ring/aead/
poly1305.rs
