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ascon-aead: rewrite internals to use inout #673

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1 change: 1 addition & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions ascon-aead/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ aead = { version = "0.6.0-rc.0", default-features = false }
subtle = { version = "2", default-features = false }
zeroize = { version = "1.6", optional = true, default-features = false, features = ["derive"] }
ascon = "0.4"
inout = { version = "0.2.0-rc.4", default-features = false }

[dev-dependencies]
hex-literal = "0.4"
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62 changes: 34 additions & 28 deletions ascon-aead/src/asconcore.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ use aead::{
consts::U16,
};
use ascon::State;
use inout::InOutBuf;
use subtle::ConstantTimeEq;

/// Produce mask for padding.
Expand Down Expand Up @@ -170,63 +171,68 @@ impl<'a, P: Parameters> AsconCore<'a, P> {
self.state[4] ^= 0x8000000000000000;
}

fn process_encrypt_inplace(&mut self, message: &mut [u8]) {
let mut blocks = message.chunks_exact_mut(16);
for block in blocks.by_ref() {
fn process_encrypt_inout(&mut self, message: InOutBuf<'_, '_, u8>) {
let (blocks, mut last_block) = message.into_chunks::<U16>();

for mut block in blocks {
// process full block of message
self.state[0] ^= u64_from_bytes(&block[..8]);
block[..8].copy_from_slice(&u64::to_le_bytes(self.state[0]));
self.state[1] ^= u64_from_bytes(&block[8..16]);
block[8..16].copy_from_slice(&u64::to_le_bytes(self.state[1]));
self.state[0] ^= u64_from_bytes(&block.get_in()[..8]);
block.get_out()[..8].copy_from_slice(&u64::to_le_bytes(self.state[0]));
self.state[1] ^= u64_from_bytes(&block.get_in()[8..16]);
block.get_out()[8..16].copy_from_slice(&u64::to_le_bytes(self.state[1]));
self.permute_state();
}

// process partial block if it exists
let mut last_block = blocks.into_remainder();
let sidx = if last_block.len() >= 8 {
self.state[0] ^= u64_from_bytes(&last_block[..8]);
last_block[..8].copy_from_slice(&u64::to_le_bytes(self.state[0]));
last_block = &mut last_block[8..];
self.state[0] ^= u64_from_bytes(&last_block.get_in()[..8]);
last_block.get_out()[..8].copy_from_slice(&u64::to_le_bytes(self.state[0]));
(_, last_block) = last_block.split_at(8);
1
} else {
0
};
self.state[sidx] ^= pad(last_block.len());
if !last_block.is_empty() {
self.state[sidx] ^= u64_from_bytes_partial(last_block);
last_block.copy_from_slice(&u64::to_le_bytes(self.state[sidx])[0..last_block.len()]);
self.state[sidx] ^= u64_from_bytes_partial(last_block.get_in());
let last_block_len = last_block.len();
last_block
.get_out()
.copy_from_slice(&u64::to_le_bytes(self.state[sidx])[0..last_block_len]);
}
}

fn process_decrypt_inplace(&mut self, ciphertext: &mut [u8]) {
let mut blocks = ciphertext.chunks_exact_mut(16);
for block in blocks.by_ref() {
fn process_decrypt_inout(&mut self, ciphertext: InOutBuf<'_, '_, u8>) {
let (blocks, mut last_block) = ciphertext.into_chunks::<U16>();
for mut block in blocks {
// process full block of ciphertext
let cx = u64_from_bytes(&block[..8]);
block[..8].copy_from_slice(&u64::to_le_bytes(self.state[0] ^ cx));
let cx = u64_from_bytes(&block.get_in()[..8]);
block.get_out()[..8].copy_from_slice(&u64::to_le_bytes(self.state[0] ^ cx));
self.state[0] = cx;
let cx = u64_from_bytes(&block[8..16]);
block[8..16].copy_from_slice(&u64::to_le_bytes(self.state[1] ^ cx));
let cx = u64_from_bytes(&block.get_in()[8..16]);
block.get_out()[8..16].copy_from_slice(&u64::to_le_bytes(self.state[1] ^ cx));
self.state[1] = cx;
self.permute_state();
}

// process partial block if it exists
let mut last_block = blocks.into_remainder();
let sidx = if last_block.len() >= 8 {
let cx = u64_from_bytes(&last_block[..8]);
last_block[..8].copy_from_slice(&u64::to_le_bytes(self.state[0] ^ cx));
let cx = u64_from_bytes(&last_block.get_in()[..8]);
last_block.get_out()[..8].copy_from_slice(&u64::to_le_bytes(self.state[0] ^ cx));
self.state[0] = cx;
last_block = &mut last_block[8..];
(_, last_block) = last_block.split_at(8);
1
} else {
0
};
self.state[sidx] ^= pad(last_block.len());
if !last_block.is_empty() {
let cx = u64_from_bytes_partial(last_block);
let cx = u64_from_bytes_partial(last_block.get_in());
self.state[sidx] ^= cx;
last_block.copy_from_slice(&u64::to_le_bytes(self.state[sidx])[0..last_block.len()]);
let last_block_len = last_block.len();
last_block
.get_out()
.copy_from_slice(&u64::to_le_bytes(self.state[sidx])[0..last_block_len]);
self.state[sidx] = clear(self.state[sidx], last_block.len()) ^ cx;
}
}
Expand All @@ -248,7 +254,7 @@ impl<'a, P: Parameters> AsconCore<'a, P> {
associated_data: &[u8],
) -> Array<u8, U16> {
self.process_associated_data(associated_data);
self.process_encrypt_inplace(message);
self.process_encrypt_inout(message.into());
Array::from(self.process_final())
}

Expand All @@ -259,7 +265,7 @@ impl<'a, P: Parameters> AsconCore<'a, P> {
expected_tag: &Array<u8, U16>,
) -> Result<(), Error> {
self.process_associated_data(associated_data);
self.process_decrypt_inplace(ciphertext);
self.process_decrypt_inout(ciphertext.into());

let tag = self.process_final();
if bool::from(tag.ct_eq(expected_tag)) {
Expand Down