Crate aes_eme2_blake3 

AES-EME2-BLAKE3

Pure Rust implementation of the AES-EME2-BLAKE3 Deterministic Authenticated Encryption (DAE) cipher.

Documentation

Security Notes

aes-eme2-blake3 is designed to provide 100% Nonce Misuse Resistance (NMR). Standard modes like AES-GCM fail catastrophically if a nonce is reused. This library uses a Synthetic Initialization Vector (SIV) architecture. BLAKE3 computes a MAC over the plaintext, associated data (AD), and nonce. This MAC is then used as the tweak for the wide-block EME2 cipher. Reusing a nonce with different data completely changes the tweak, maintaining absolute security.

Furthermore, unlike stream ciphers, EME2 acts as a Strong Pseudorandom Permutation (SPRP). It processes your entire payload as a single, massive cryptographic block. If an attacker alters even a single bit of the ciphertext, the decryption process will scramble the entire plaintext into unrecognizable garbage, guaranteeing the subsequent BLAKE3 authentication check will fail.

All implementations contained in the crate rely on the constant-time guarantees of the underlying aes and blake3 crates, while the EME2 core logic itself avoids data-dependent branching.

Performance & Architecture

We consciously trade pure throughput for maximum operational security. In our benchmarks, aes-eme2-blake3 achieves a peak decryption throughput of ~197 MiB/s, whereas a hardware-accelerated AES-GCM implementation achieves ~1.21 GiB/s (roughly 6x faster).

This performance difference is entirely expected and reasonable given the architectural goals. AES-GCM is a single-pass stream cipher. EME2 is a true wide-block cipher that requires two full passes over the entire plaintext buffer to build an XOR sum, ensuring that every byte depends mathematically on every other byte.

Throughput Benchmarks

Payload Size	AES-EME2-BLAKE3 Encrypt	AES-EME2-BLAKE3 Decrypt	AES-GCM Encrypt	AES-GCM Decrypt
32 B	45.9 MiB/s	47.1 MiB/s	209.8 MiB/s	175.2 MiB/s
64 B	75.4 MiB/s	70.6 MiB/s	345.3 MiB/s	323.7 MiB/s
1 KB	156.4 MiB/s	156.5 MiB/s	1000.6 MiB/s	894.4 MiB/s
64 KB	197.2 MiB/s	197.3 MiB/s	1.21 GiB/s	1.21 GiB/s
512 KB	196.8 MiB/s	194.9 MiB/s	1.15 GiB/s	1.15 GiB/s
1 MB	197.6 MiB/s	194.8 MiB/s	1.17 GiB/s	1.20 GiB/s
10 MB	185.6 MiB/s	188.6 MiB/s	1.16 GiB/s	1.14 GiB/s

License

Licensed under either of:

• Apache License, Version 2.0
• MIT license

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Usage

Simple usage (allocating, no associated data):

// NOTE: requires the `getrandom` feature is enabled

use aes_eme2_blake3::{
    aead::{Aead, AeadCore, Generate, Key, KeyInit},
    Aes256Eme2Blake3, Nonce // Or `Aes128Eme2Blake3`
};

let key = Key::<Aes256Eme2Blake3>::generate();
let cipher = Aes256Eme2Blake3::new(&key);

let nonce = Nonce::generate(); // MUST be unique per message
let ciphertext = cipher.encrypt(&nonce, b"plaintext message".as_ref()).map_err(|_| "encrypt failed")?;

let plaintext = cipher.decrypt(&nonce, ciphertext.as_ref()).map_err(|_| "decrypt failed")?;
assert_eq!(&plaintext, b"plaintext message");

In-place Usage

The AeadInOut::encrypt_in_place and AeadInOut::decrypt_in_place methods accept any type that impls the aead::Buffer trait which contains the plaintext for encryption or ciphertext for decryption.

Enabling the arrayvec feature of this crate will provide an impl of aead::Buffer for arrayvec::ArrayVec (re-exported from the aead crate as aead::arrayvec::ArrayVec), and enabling the bytes feature of this crate will provide an impl of aead::Buffer for bytes::BytesMut (re-exported from the aead crate as aead::bytes::BytesMut).

It can then be passed as the buffer parameter to the in-place encrypt and decrypt methods:

// NOTE: requires the `arrayvec` and `getrandom` features are enabled

use aes_eme2_blake3::{
    aead::{AeadCore, AeadInOut, Generate, Key, KeyInit, arrayvec::ArrayVec},
    Aes256Eme2Blake3, Nonce // Or `Aes128Eme2Blake3`
};

let key = Key::<Aes256Eme2Blake3>::generate();
let cipher = Aes256Eme2Blake3::new(&key);

let nonce = Nonce::generate(); // MUST be unique per message
let mut buffer: ArrayVec<u8, 128> = ArrayVec::new(); // Note: buffer needs 24-bytes overhead for auth tag
buffer.try_extend_from_slice(b"plaintext message").unwrap();

// Encrypt `buffer` in-place, replacing the plaintext contents with ciphertext
cipher.encrypt_in_place(&nonce, b"", &mut buffer).map_err(|_| "encrypt failed")?;

// `buffer` now contains the message ciphertext
assert_ne!(buffer.as_ref(), b"plaintext message");

// Decrypt `buffer` in-place, replacing its ciphertext context with the original plaintext
cipher.decrypt_in_place(&nonce, b"", &mut buffer).map_err(|_| "decrypt failed")?;
assert_eq!(buffer.as_ref(), b"plaintext message");

Re-exports

pub use aead;

pub use aes;aes

Structs

Eme2Blake3

A SIV (Synthetic Initialization Vector) AEAD cipher using EME2 and BLAKE3.

Error

Error type.

Enums

TagPosition

Enum which specifies tag position used by an AEAD algorithm.

Traits

AeadCore

Authenticated Encryption with Associated Data (AEAD) algorithm.

AeadInOut

In-place and inout AEAD trait which handles the authentication tag as a return value/separate parameter.

KeyInit

Types which can be initialized from a key.

KeySizeUser

Types which use key for initialization.

ZeroizeMarkerzeroize

A marker trait used to conditionally enforce ZeroizeOnDrop bounds when the zeroize feature is enabled.

Type Aliases

Aes128Eme2Blake3aes

EME2-BLAKE3 with AES-128.

Aes256Eme2Blake3aes

EME2-BLAKE3 with AES-256.

Key

Key used by KeySizeUser implementors.

Nonce

External nonce for Eme2Blake3.

Tag

Tag for Eme2Blake3.