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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::fmt;
use crate::{
aead::Aead,
constants::{Cipher, Version},
err::{Error, Res, sec::SEC_ERROR_BAD_DATA},
p11::SymKey,
};
pub const AEAD_NULL_TAG: &[u8] = &[0x0a; 16];
pub struct AeadNull {}
impl AeadNull {
fn decrypt_check(&self, _count: u64, _aad: &[u8], input: &[u8]) -> Res<usize> {
if input.len() < self.expansion() {
return Err(Error::from(SEC_ERROR_BAD_DATA));
}
let len_encrypted = input
.len()
.checked_sub(self.expansion())
.ok_or_else(|| Error::from(SEC_ERROR_BAD_DATA))?;
// Check that:
// 1) expansion is all zeros and
// 2) if the encrypted data is also supplied that at least some values are no zero
// (otherwise padding will be interpreted as a valid packet)
if &input[len_encrypted..] == AEAD_NULL_TAG
&& (len_encrypted == 0 || input[..len_encrypted].iter().any(|x| *x != 0x0))
{
Ok(len_encrypted)
} else {
Err(Error::from(SEC_ERROR_BAD_DATA))
}
}
}
impl Aead for AeadNull {
fn new(_version: Version, _cipher: Cipher, _secret: &SymKey, _prefix: &str) -> Res<Self> {
Ok(Self {})
}
fn expansion(&self) -> usize {
AEAD_NULL_TAG.len()
}
fn encrypt<'a>(
&self,
_count: u64,
_aad: &[u8],
input: &[u8],
output: &'a mut [u8],
) -> Res<&'a [u8]> {
let l = input.len();
output[..l].copy_from_slice(input);
output[l..l + self.expansion()].copy_from_slice(AEAD_NULL_TAG);
Ok(&output[..l + self.expansion()])
}
fn encrypt_in_place(&self, _count: u64, _aad: &[u8], data: &mut [u8]) -> Res<usize> {
let pos = data.len() - self.expansion();
data[pos..].copy_from_slice(AEAD_NULL_TAG);
Ok(data.len())
}
fn decrypt<'a>(
&self,
count: u64,
aad: &[u8],
input: &[u8],
output: &'a mut [u8],
) -> Res<&'a [u8]> {
self.decrypt_check(count, aad, input).map(|len| {
output[..len].copy_from_slice(&input[..len]);
&output[..len]
})
}
fn decrypt_in_place(&self, count: u64, aad: &[u8], data: &mut [u8]) -> Res<usize> {
self.decrypt_check(count, aad, data)
}
}
impl fmt::Debug for AeadNull {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "[NULL AEAD]")
}
}