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|
//! Implementation of AEAD using pure Rust cryptographic libraries.
use std::cmp;
use cipher::{BlockCipher, NewBlockCipher};
use cipher::block::Block;
use cipher::consts::U16;
use eax::online::{Eax, Encrypt, Decrypt};
use generic_array::{ArrayLength, GenericArray};
use crate::{Error, Result};
use crate::crypto::aead::{Aead, CipherOp};
use crate::seal;
use crate::types::{AEADAlgorithm, SymmetricAlgorithm};
trait GenericArrayExt<T, N: ArrayLength<T>> {
const LEN: usize;
/// Like [`GenericArray::from_slice`], but fallible.
fn try_from_slice(slice: &[T]) -> Result<&GenericArray<T, N>> {
if slice.len() == Self::LEN {
Ok(GenericArray::from_slice(slice))
} else {
Err(Error::InvalidArgument(
format!("Invalid slice length, want {}, got {}",
Self::LEN, slice.len())).into())
}
}
}
impl<T, N: ArrayLength<T>> GenericArrayExt<T, N> for GenericArray<T, N> {
const LEN: usize = N::USIZE;
}
impl<Cipher> Aead for Eax<Cipher, Encrypt>
where
Cipher: BlockCipher<BlockSize = U16> + NewBlockCipher + Clone,
Cipher::ParBlocks: ArrayLength<Block<Cipher>>,
{
fn update(&mut self, ad: &[u8]) {
self.update_assoc(ad)
}
fn digest_size(&self) -> usize {
eax::Tag::LEN
}
fn digest(&mut self, digest: &mut [u8]) {
let tag = self.tag_clone();
digest[..tag.len()].copy_from_slice(&tag[..]);
}
fn encrypt(&mut self, dst: &mut [u8], src: &[u8]) {
let len = cmp::min(dst.len(), src.len());
dst[..len].copy_from_slice(&src[..len]);
Self::encrypt(self, &mut dst[..len])
}
fn decrypt(&mut self, _dst: &mut [u8], _src: &[u8]) {
panic!("AEAD decryption called in the encryption context")
}
}
impl<Cipher> Aead for Eax<Cipher, Decrypt>
where
Cipher: BlockCipher<BlockSize = U16> + NewBlockCipher + Clone,
Cipher::ParBlocks: ArrayLength<Block<Cipher>>,
{
fn update(&mut self, ad: &[u8]) {
self.update_assoc(ad)
}
fn digest_size(&self) -> usize {
eax::Tag::LEN
}
fn digest(&mut self, digest: &mut [u8]) {
let tag = self.tag_clone();
digest[..tag.len()].copy_from_slice(&tag[..]);
}
fn encrypt(&mut self, _dst: &mut [u8], _src: &[u8]) {
panic!("AEAD encryption called in the decryption context")
}
fn decrypt(&mut self, dst: &mut [u8], src: &[u8]) {
let len = core::cmp::min(dst.len(), src.len());
dst[..len].copy_from_slice(&src[..len]);
self.decrypt_unauthenticated_hazmat(&mut dst[..len])
}
}
impl<Cipher, Op> seal::Sealed for Eax<Cipher, Op>
where
Cipher: BlockCipher<BlockSize = U16> + NewBlockCipher + Clone,
Cipher::ParBlocks: ArrayLength<Block<Cipher>>,
Op: eax::online::CipherOp,
{}
impl AEADAlgorithm {
pub(crate) fn context(
&self,
sym_algo: SymmetricAlgorithm,
key: &[u8],
nonce: &[u8],
op: CipherOp,
) -> Result<Box<dyn Aead>> {
match self {
AEADAlgorithm::EAX => match sym_algo {
SymmetricAlgorithm::AES128 => match op {
CipherOp::Encrypt => Ok(Box::new(
Eax::<aes::Aes128, Encrypt>::with_key_and_nonce(
GenericArray::try_from_slice(key)?,
GenericArray::try_from_slice(nonce)?))),
CipherOp::Decrypt => Ok(Box::new(
Eax::<aes::Aes128, Decrypt>::with_key_and_nonce(
GenericArray::try_from_slice(key)?,
GenericArray::try_from_slice(nonce)?))),
}
SymmetricAlgorithm::AES192 => match op {
CipherOp::Encrypt => Ok(Box::new(
Eax::<aes::Aes192, Encrypt>::with_key_and_nonce(
GenericArray::try_from_slice(key)?,
GenericArray::try_from_slice(nonce)?))),
CipherOp::Decrypt => Ok(Box::new(
Eax::<aes::Aes192, Decrypt>::with_key_and_nonce(
GenericArray::try_from_slice(key)?,
GenericArray::try_from_slice(nonce)?))),
}
SymmetricAlgorithm::AES256 => match op {
CipherOp::Encrypt => Ok(Box::new(
Eax::<aes::Aes256, Encrypt>::with_key_and_nonce(
GenericArray::try_from_slice(key)?,
GenericArray::try_from_slice(nonce)?))),
CipherOp::Decrypt => Ok(Box::new(
Eax::<aes::Aes256, Decrypt>::with_key_and_nonce(
GenericArray::try_from_slice(key)?,
GenericArray::try_from_slice(nonce)?))),
}
| SymmetricAlgorithm::IDEA
| SymmetricAlgorithm::TripleDES
| SymmetricAlgorithm::CAST5
| SymmetricAlgorithm::Blowfish
| SymmetricAlgorithm::Twofish
| SymmetricAlgorithm::Camellia128
| SymmetricAlgorithm::Camellia192
| SymmetricAlgorithm::Camellia256
| SymmetricAlgorithm::Private(_)
| SymmetricAlgorithm::Unknown(_)
| SymmetricAlgorithm::Unencrypted =>
Err(Error::UnsupportedSymmetricAlgorithm(sym_algo).into()),
},
AEADAlgorithm::OCB =>
Err(Error::UnsupportedAEADAlgorithm(*self).into()),
AEADAlgorithm::GCM =>
Err(Error::UnsupportedAEADAlgorithm(*self).into()),
AEADAlgorithm::Private(_) | AEADAlgorithm::Unknown(_) =>
Err(Error::UnsupportedAEADAlgorithm(*self).into()),
}
}
}
|
