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ocb3: use sealed traits for nonce and tag sizes #596

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Mar 27, 2024
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ocb3: use sealed traits for nonce and tag sizes #596

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19005cb
ocb3: use sealed tratis for nonce and tag sizes
newpavlov Mar 27, 2024
ca13670
Add docs for sealed traits
newpavlov Mar 27, 2024
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92 changes: 45 additions & 47 deletions ocb3/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,12 +20,8 @@ pub use aead::{
};

use crate::util::{double, inplace_xor, ntz, Block};
use aead::generic_array::{
typenum::{GrEq, IsGreaterOrEqual, IsLessOrEqual, LeEq, NonZero},
ArrayLength,
};
use cipher::{
consts::{U0, U12, U15, U16, U6},
consts::{U0, U12, U16},
BlockDecrypt, BlockEncrypt, BlockSizeUser,
};
use core::marker::PhantomData;
Expand Down Expand Up @@ -58,6 +54,32 @@ pub type Nonce<NonceSize> = GenericArray<u8, NonceSize>;
/// OCB3 tag
pub type Tag<TagSize> = GenericArray<u8, TagSize>;

mod sealed {
use aead::generic_array::{
typenum::{GrEq, IsGreaterOrEqual, IsLessOrEqual, LeEq, NonZero, U15, U16, U6},
ArrayLength,
};

pub trait NonceSizes: ArrayLength<u8> {}

impl<T> NonceSizes for T
where
T: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
GrEq<T, U6>: NonZero,
LeEq<T, U15>: NonZero,
{
}

pub trait TagSizes: ArrayLength<u8> {}

impl<T> TagSizes for T
where
T: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
LeEq<T, U16>: NonZero,
{
}
}
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/// OCB3: generic over a block cipher implementation, nonce size, and tag size.
///
/// - `NonceSize`: max of 15-bytes, default and recommended size of 12-bytes (96-bits).
Expand Down Expand Up @@ -101,11 +123,8 @@ pub type Tag<TagSize> = GenericArray<u8, TagSize>;
#[derive(Clone)]
pub struct Ocb3<Cipher, NonceSize = U12, TagSize = U16>
where
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
TagSize: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
GrEq<NonceSize, U6>: NonZero,
LeEq<NonceSize, U15>: NonZero,
LeEq<TagSize, U16>: NonZero,
NonceSize: sealed::NonceSizes,
TagSize: sealed::TagSizes,
{
cipher: Cipher,
nonce_size: PhantomData<NonceSize>,
Expand All @@ -124,23 +143,17 @@ type Sum = GenericArray<u8, SumSize>;
impl<Cipher, NonceSize, TagSize> KeySizeUser for Ocb3<Cipher, NonceSize, TagSize>
where
Cipher: KeySizeUser,
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
TagSize: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
GrEq<NonceSize, U6>: NonZero,
LeEq<NonceSize, U15>: NonZero,
LeEq<TagSize, U16>: NonZero,
NonceSize: sealed::NonceSizes,
TagSize: sealed::TagSizes,
{
type KeySize = Cipher::KeySize;
}

impl<Cipher, NonceSize, TagSize> KeyInit for Ocb3<Cipher, NonceSize, TagSize>
where
Cipher: BlockSizeUser<BlockSize = U16> + BlockEncrypt + KeyInit + BlockDecrypt,
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
TagSize: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
GrEq<NonceSize, U6>: NonZero,
LeEq<NonceSize, U15>: NonZero,
LeEq<TagSize, U16>: NonZero,
NonceSize: sealed::NonceSizes,
TagSize: sealed::TagSizes,
{
fn new(key: &aead::Key<Self>) -> Self {
Cipher::new(key).into()
Expand All @@ -149,11 +162,8 @@ where

impl<Cipher, NonceSize, TagSize> AeadCore for Ocb3<Cipher, NonceSize, TagSize>
where
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
TagSize: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
GrEq<NonceSize, U6>: NonZero,
LeEq<NonceSize, U15>: NonZero,
LeEq<TagSize, U16>: NonZero,
NonceSize: sealed::NonceSizes,
TagSize: sealed::TagSizes,
{
type NonceSize = NonceSize;
type TagSize = TagSize;
Expand All @@ -163,11 +173,8 @@ where
impl<Cipher, NonceSize, TagSize> From<Cipher> for Ocb3<Cipher, NonceSize, TagSize>
where
Cipher: BlockSizeUser<BlockSize = U16> + BlockEncrypt + BlockDecrypt,
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
TagSize: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
GrEq<NonceSize, U6>: NonZero,
LeEq<NonceSize, U15>: NonZero,
LeEq<TagSize, U16>: NonZero,
NonceSize: sealed::NonceSizes,
TagSize: sealed::TagSizes,
{
fn from(cipher: Cipher) -> Self {
let (ll_star, ll_dollar, ll) = key_dependent_variables(&cipher);
Expand Down Expand Up @@ -206,11 +213,8 @@ fn key_dependent_variables<Cipher: BlockSizeUser<BlockSize = U16> + BlockEncrypt
impl<Cipher, NonceSize, TagSize> AeadInPlace for Ocb3<Cipher, NonceSize, TagSize>
where
Cipher: BlockSizeUser<BlockSize = U16> + BlockEncrypt + BlockDecrypt,
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
TagSize: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
GrEq<NonceSize, U6>: NonZero,
LeEq<NonceSize, U15>: NonZero,
LeEq<TagSize, U16>: NonZero,
NonceSize: sealed::NonceSizes,
TagSize: sealed::TagSizes,
{
fn encrypt_in_place_detached(
&self,
Expand Down Expand Up @@ -291,11 +295,8 @@ where
impl<Cipher, NonceSize, TagSize> Ocb3<Cipher, NonceSize, TagSize>
where
Cipher: BlockSizeUser<BlockSize = U16> + BlockEncrypt + BlockDecrypt,
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
TagSize: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
GrEq<NonceSize, U6>: NonZero,
LeEq<NonceSize, U15>: NonZero,
LeEq<TagSize, U16>: NonZero,
NonceSize: sealed::NonceSizes,
TagSize: sealed::TagSizes,
{
/// Decrypts in place and returns expected tag.
pub(crate) fn decrypt_in_place_return_tag(
Expand Down Expand Up @@ -444,7 +445,7 @@ where
/// in https://www.rfc-editor.org/rfc/rfc7253.html#section-4.2
fn nonce_dependent_variables<
Cipher: BlockSizeUser<BlockSize = U16> + BlockEncrypt,
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
NonceSize: sealed::NonceSizes,
>(
cipher: &Cipher,
nn: &Nonce<NonceSize>,
Expand Down Expand Up @@ -483,7 +484,7 @@ fn nonce_dependent_variables<
/// in https://www.rfc-editor.org/rfc/rfc7253.html#section-4.2
fn initial_offset<
Cipher: BlockSizeUser<BlockSize = U16> + BlockEncrypt,
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
NonceSize: sealed::NonceSizes,
>(
cipher: &Cipher,
nn: &Nonce<NonceSize>,
Expand All @@ -502,11 +503,8 @@ fn initial_offset<
impl<Cipher, NonceSize, TagSize> Ocb3<Cipher, NonceSize, TagSize>
where
Cipher: BlockSizeUser<BlockSize = U16> + BlockEncrypt,
NonceSize: ArrayLength<u8> + IsGreaterOrEqual<U6> + IsLessOrEqual<U15>,
TagSize: ArrayLength<u8> + NonZero + IsLessOrEqual<U16>,
GrEq<NonceSize, U6>: NonZero,
LeEq<NonceSize, U15>: NonZero,
LeEq<TagSize, U16>: NonZero,
NonceSize: sealed::NonceSizes,
TagSize: sealed::TagSizes,
{
/// Computes HASH function defined in https://www.rfc-editor.org/rfc/rfc7253.html#section-4.1
fn hash(&self, associated_data: &[u8]) -> Sum {
Expand Down