Crate aes

Pure Rust implementation of the Advanced Encryption Standard (a.k.a. Rijndael)

Supported backends

This crate provides multiple backends including a portable pure Rust backend as well as ones based on CPU intrinsics.

By default, it performs runtime detection of CPU intrinsics and uses them if they are available.

“soft” portable backend

As a baseline implementation, this crate provides a constant-time pure Rust implementation based on fixslicing, a more advanced form of bitslicing implemented entirely in terms of bitwise arithmetic with no use of any lookup tables or data-dependent branches.

Enabling the compact Cargo feature will reduce the code size of this backend at the cost of decreased performance (using a modified form of the fixslicing technique called “semi-fixslicing”).

ARMv8 intrinsics (nightly-only)

On aarch64 targets including aarch64-apple-darwin (Apple M1) and Linux targets such as aarch64-unknown-linux-gnu and aarch64-unknown-linux-musl, support for using AES intrinsics provided by the ARMv8 Cryptography Extensions is available when using the nightly compiler, and can be enabled using the armv8 crate feature.

On Linux and macOS, when the armv8 feature is enabled support for AES intrinsics is autodetected at runtime. On other platforms the crypto target feature must be enabled via RUSTFLAGS.

x86/x86_64 intrinsics (AES-NI)

By default this crate uses runtime detection on i686/x86_64 targets in order to determine if AES-NI is available, and if it is not, it will fallback to using a constant-time software implementation.

Passing RUSTFLAGS=-Ctarget-feature=+aes,+ssse3 explicitly at compile-time will override runtime detection and ensure that AES-NI is always used. Programs built in this manner will crash with an illegal instruction on CPUs which do not have AES-NI enabled.

Note: runtime detection is not possible on SGX targets. Please use the afforementioned RUSTFLAGS to leverage AES-NI on these targets.

Usage example

use aes::{Aes128, Block, ParBlocks};
use aes::cipher::{
    BlockCipher, BlockEncrypt, BlockDecrypt, NewBlockCipher,
    generic_array::GenericArray,
};

let key = GenericArray::from_slice(&[0u8; 16]);
let mut block = Block::default();
let mut block8 = ParBlocks::default();

// Initialize cipher
let cipher = Aes128::new(&key);

let block_copy = block.clone();

// Encrypt block in-place
cipher.encrypt_block(&mut block);

// And decrypt it back
cipher.decrypt_block(&mut block);
assert_eq!(block, block_copy);

// We can encrypt 8 blocks simultaneously using
// instruction-level parallelism
let block8_copy = block8.clone();
cipher.encrypt_par_blocks(&mut block8);
cipher.decrypt_par_blocks(&mut block8);
assert_eq!(block8, block8_copy);

For implementations of block cipher modes of operation see block-modes crate.

Re-exports

pub use cipher;

Structs

Aes128	AES-128 block cipher instance
Aes128Ctr	ctr AES-128 in CTR mode
Aes192	AES-192 block cipher instance
Aes192Ctr	ctr AES-192 in CTR mode
Aes256	AES-256 block cipher instance
Aes256Ctr	ctr AES-256 in CTR mode

Constants

BLOCK_SIZE

Size of an AES block (128-bits; 16-bytes)

Traits

BlockCipher	Trait which marks a type as being a block cipher.
BlockDecrypt	Decrypt-only functionality for block ciphers.
BlockEncrypt	Encrypt-only functionality for block ciphers.
NewBlockCipher	Instantiate a BlockCipher algorithm.

Type Definitions

Block	128-bit AES block
ParBlocks	8 x 128-bit AES blocks to be processed in parallel