ring/aead/chacha20_poly1305/integrated.rs
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// Copyright 2015-2025 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 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::{
super::{NONCE_LEN, TAG_LEN},
chacha::Overlapping,
check_input_lengths, Aad, InputTooLongError, Key, Nonce, Tag, KEY_LEN,
};
use cfg_if::cfg_if;
macro_rules! declare_open {
( $name:ident ) => {
prefixed_extern! {
fn $name(
out_plaintext: *mut u8,
ciphertext: *const u8,
plaintext_len: usize,
ad: *const u8,
ad_len: usize,
data: &mut InOut<open_data_in>,
);
}
};
}
macro_rules! declare_seal {
( $name:ident ) => {
prefixed_extern! {
fn $name(
out_ciphertext: *mut u8,
plaintext: *const u8,
plaintext_len: usize,
ad: *const u8,
ad_len: usize,
data: &mut InOut<seal_data_in>,
);
}
};
}
cfg_if! {
if #[cfg(all(target_arch = "aarch64", target_endian = "little"))] {
use crate::cpu::arm::Neon;
type RequiredCpuFeatures = Neon;
type OptionalCpuFeatures = ();
} else {
use crate::cpu::intel::{Avx2, Bmi2, Sse41};
type RequiredCpuFeatures = Sse41;
type OptionalCpuFeatures = (Avx2, Bmi2);
}
}
pub(super) fn seal(
Key(key): &Key,
nonce: Nonce,
aad: Aad<&[u8]>,
in_out: &mut [u8],
required_cpu_features: RequiredCpuFeatures,
optional_cpu_features: Option<OptionalCpuFeatures>,
) -> Result<Tag, InputTooLongError> {
check_input_lengths(aad, in_out)?;
// XXX: BoringSSL uses `alignas(16)` on `key` instead of on the
// structure, but Rust can't do that yet; see
// https://github.com/rust-lang/rust/issues/73557.
//
// Keep in sync with the anonymous struct of BoringSSL's
// `chacha20_poly1305_seal_data`.
#[repr(align(16), C)]
#[derive(Clone, Copy)]
struct seal_data_in {
key: [u32; KEY_LEN / 4],
counter: u32,
nonce: [u8; NONCE_LEN],
extra_ciphertext: *const u8,
extra_ciphertext_len: usize,
}
let mut data = InOut {
input: seal_data_in {
key: *key.words_less_safe(),
counter: 0,
nonce: *nonce.as_ref(),
extra_ciphertext: core::ptr::null(),
extra_ciphertext_len: 0,
},
};
// Encrypts `plaintext_len` bytes from `plaintext` and writes them to `out_ciphertext`.
let output = in_out.as_mut_ptr();
let input = in_out.as_ptr();
let len = in_out.len();
let ad = aad.as_ref().as_ptr();
let ad_len = aad.as_ref().len();
#[allow(clippy::needless_late_init)]
let tag;
cfg_if! {
if #[cfg(all(target_arch = "aarch64", target_endian = "little"))] {
declare_seal! { chacha20_poly1305_seal }
let _: Neon = required_cpu_features;
let _: Option<()> = optional_cpu_features;
tag = unsafe {
chacha20_poly1305_seal(output, input, len, ad, ad_len, &mut data);
&data.out.tag
};
} else {
let _: Sse41 = required_cpu_features;
if matches!(optional_cpu_features, Some((Avx2 { .. }, Bmi2 { .. }))) {
declare_seal! { chacha20_poly1305_seal_avx2 }
tag = unsafe {
chacha20_poly1305_seal_avx2(output, input, len, ad, ad_len, &mut data);
&data.out.tag
};
} else {
declare_seal! { chacha20_poly1305_seal_sse41 }
tag = unsafe {
chacha20_poly1305_seal_sse41(output, input, len, ad, ad_len, &mut data);
&data.out.tag
};
}
}
}
Ok(Tag(*tag))
}
pub(super) fn open(
Key(key): &Key,
nonce: Nonce,
aad: Aad<&[u8]>,
in_out: Overlapping<'_>,
required_cpu_features: RequiredCpuFeatures,
optional_cpu_features: Option<OptionalCpuFeatures>,
) -> Result<Tag, InputTooLongError> {
check_input_lengths(aad, in_out.input())?;
// XXX: BoringSSL uses `alignas(16)` on `key` instead of on the
// structure, but Rust can't do that yet; see
// https://github.com/rust-lang/rust/issues/73557.
//
// Keep in sync with the anonymous struct of BoringSSL's
// `chacha20_poly1305_open_data`.
#[derive(Copy, Clone)]
#[repr(align(16), C)]
struct open_data_in {
key: [u32; KEY_LEN / 4],
counter: u32,
nonce: [u8; NONCE_LEN],
}
let mut data = InOut {
input: open_data_in {
key: *key.words_less_safe(),
counter: 0,
nonce: *nonce.as_ref(),
},
};
in_out.with_input_output_len(|input, output, len| {
let ad = aad.as_ref().as_ptr();
let ad_len = aad.as_ref().len();
#[allow(clippy::needless_late_init)]
let tag;
cfg_if! {
if #[cfg(all(target_arch = "aarch64", target_endian = "little"))] {
declare_open! { chacha20_poly1305_open }
let _: Neon = required_cpu_features;
let _: Option<()> = optional_cpu_features;
tag = unsafe {
chacha20_poly1305_open(output, input, len, ad, ad_len, &mut data);
&data.out.tag
};
} else {
let _: Sse41 = required_cpu_features;
if matches!(optional_cpu_features, Some((Avx2 { .. }, Bmi2 { .. }))) {
declare_open! { chacha20_poly1305_open_avx2 }
tag = unsafe {
chacha20_poly1305_open_avx2(output, input, len, ad, ad_len, &mut data);
&data.out.tag
};
} else {
declare_open! { chacha20_poly1305_open_sse41 }
tag = unsafe {
chacha20_poly1305_open_sse41(output, input, len, ad, ad_len, &mut data);
&data.out.tag
};
}
}
}
Ok(Tag(*tag))
})
}
// Keep in sync with BoringSSL's `chacha20_poly1305_open_data` and
// `chacha20_poly1305_seal_data`.
#[repr(C)]
pub(super) union InOut<T>
where
T: Copy,
{
pub(super) input: T,
pub(super) out: Out,
}
// It isn't obvious whether the assembly code works for tags that aren't
// 16-byte aligned. In practice it will always be 16-byte aligned because it
// is embedded in a union where the other member of the union is 16-byte
// aligned.
#[derive(Clone, Copy)]
#[repr(align(16), C)]
pub(super) struct Out {
pub(super) tag: [u8; TAG_LEN],
}