ring/aead/poly1305/ffi_fallback.rs
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// Copyright 2015-2025 Brian Smith.
// Portions Copyright (c) 2014, 2015, 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 THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR 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 super::{Key, Tag, KEY_LEN, TAG_LEN};
use crate::c;
use core::num::NonZeroUsize;
// XXX/TODO(MSRV): change to `pub(super)`.
pub(in super::super) struct State {
state: poly1305_state_st,
}
// Keep in sync with `poly1305_state_st` in poly1305.c
#[repr(C, align(64))]
struct poly1305_state_st {
r0: u32,
r1: u32,
r2: u32,
r3: u32,
r4: u32,
s1: u32,
s2: u32,
s3: u32,
s4: u32,
h0: u32,
h1: u32,
h2: u32,
h3: u32,
h4: u32,
key: [u8; 16],
}
impl State {
pub(super) fn new_context(Key { key_and_nonce }: Key) -> super::Context {
prefixed_extern! {
fn CRYPTO_poly1305_init(state: &mut poly1305_state_st, key: &[u8; KEY_LEN]);
}
let mut r = Self {
state: poly1305_state_st {
r0: 0,
r1: 0,
r2: 0,
r3: 0,
r4: 0,
s1: 0,
s2: 0,
s3: 0,
s4: 0,
h0: 0,
h1: 0,
h2: 0,
h3: 0,
h4: 0,
key: [0u8; 16],
},
};
unsafe { CRYPTO_poly1305_init(&mut r.state, &key_and_nonce) }
super::Context::Fallback(r)
}
// `input.len % BLOCK_LEN == 0` must be true for every call except the
// final one.
pub(super) fn update_internal(&mut self, input: &[u8]) {
prefixed_extern! {
fn CRYPTO_poly1305_update(
state: &mut poly1305_state_st,
input: *const u8,
in_len: c::NonZero_size_t);
}
if let Some(len) = NonZeroUsize::new(input.len()) {
let input = input.as_ptr();
unsafe { CRYPTO_poly1305_update(&mut self.state, input, len) }
}
}
pub(super) fn finish(mut self) -> Tag {
prefixed_extern! {
fn CRYPTO_poly1305_finish(statep: &mut poly1305_state_st, mac: &mut [u8; TAG_LEN]);
}
let mut tag = Tag([0u8; TAG_LEN]);
unsafe { CRYPTO_poly1305_finish(&mut self.state, &mut tag.0) }
tag
}
}