A pure-Rust platform-agnostic AES library, focused on reusability and optimal performance.

This library guarantees the best performance on the target_cpu (if correctly specified). This currently has quite a few implementations, among which it automatically decides the best (most performant) using rustc's target_feature flags.

The implementations and their requirements

Nightly-only means a Nightly compiler is required, and the nightly crate feature must be enabled.

All the implementations are well-tested, but it is still possible for bugs to creep through, especially for the Nightly-only implementations, as those are on the bleeding edge of the compiler. In case you discover a bug, please feel free to file an issue at my repository.

For Scalar AES (1 block at a time)

Implementation	Architecture	Target Feature
AES-NI	x86/x86_64	aes
AES-Neon	aarch64/arm64ec	aes
	arm	v8+aes	Nightly-only
AES-RV	riscv32/riscv64	zkne+zknd	Nightly-only
AES-PPC	powerpc/powerpc64	power8-crypto	Nightly-only
Constant-time Software AES	None	None	Requires the constant-time crate feature
Table-based Software AES	None	None	Based on Rijmen and Daemen's optimized implementation (available on their website)

The Constant-time Software AES implementation guards against side-channel attacks, at the cost of some speed. This will only be used if no accelerated AES implementation is found, and the constant-time crate feature is enabled (because all hardware-accelerated AES implementations are always constant-time).

For X2 Vector AES (2 blocks in parallel)

Implementation	Architecture	Target Feature
AES-NI	x86/x86_64	vaes	Nightly-only

For X4 Vector AES (4 blocks in parallel)

Implementation	Architecture	Target Feature
AES-NI	x86/x86_64	vaes+avx512f	Nightly-only

For Vector AES, if no accelerated version is found, then a tuple-based implementation is used. That is, if an x86_64 machine has vaes, but not avx512f, then AesBlockX4 will be represented as a wrapper over (AesBlockX2, AesBlockX2) (which still benefits from the X2 parallelism offered by vaes).

If you are unsure, use target_cpu=native (if not cross-compiling; otherwise you can use target_cpu=<CPU of your target machine> with the appropriate target triple) in the RUSTFLAGS environment variable, and use the nightly feature only if you are using a nightly compiler.

Minimum Supported Rust version

I typically don't maintain a strict MSRV. Normally, it would be the latest stable at the time of release if the nightly crate feature is not enabled, otherwise it would be the latest nightly at the time of release.

Warning

Using the wrong target_feature flags may lead to the binary crashing due to an "Unknown Instruction" error. This library uses these flags to use the CPU intrinsics to maximize performance. If you are unsure what target_features are supported on your CPU, use the command

rustc --print cfg -C target-cpu=native

Using the nightly feature when not using a nightly compiler can lead to compile failures, so use this only if you are using a nightly compiler.

This is a low-level crate, and is supposed to be used as a cryptographic primitive. This crate only implements AES-ECB, which is NOT a secure cipher. Rather, this crate should be used as a building block for implementing higher-level algorithms in a platform-independent and performant way.