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

Supported platforms

This crate provides two different backends based on what target features are available:

• “soft” portable constant-time implementation based on fixslicing. 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”).
• AES-NI accelerated implementation for i686/x86_64 target architectures with target-feature=+aes, as well as an accelerated AES-CTR implementation with target-feature=+aes,+ssse3

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.

Usage example

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

let key = GenericArray::from_slice(&[0u8; 16]);
let mut block = GenericArray::clone_from_slice(&[0u8; 16]);
let mut block8 = GenericArray::clone_from_slice(&[block; 8]);

// 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.