Bessie

docs.rs — crates.io lib — crates.io bin

Bessie is an authenticated, chunked cipher based on BLAKE3. The design has been stable for a while, but it hasn't been audited or used in the real world as far as I know. Use with caution.

Features and design goals:

• general-purpose authenticated encryption
• no practical limits on the number or size of messages
• internal random nonce generation, to prevent mistakes
• streaming encryption and decryption of large messages
• seekable decryption of large messages
• key commitment

Non-features and non-goals:

• Not formally/strongly misuse-resistant. Generating random nonces internally avoids a lot of common mistakes, and mixing auth tags into the stream makes nonce reuse somewhat less catastrophic. But nonce reuse does allow an attacker to mix-and-match chunks from different messages, and chunked/streaming constructions are also inherently vulnerable to nonce reuse exploits that all-at-once constructions like AES-SIV are not.
• No built-in associated data parameters. Callers who need associated data can mix it with their key using a KDF or a keyed hash.
• Not optimal as a building block for encrypted network protocols like TLS. TLS-oriented ciphers like AES-GCM and ChaCha20-Poly1305 prioritize bytes on the wire and short-message performance above all else. They're often used with ephemeral keys, where random nonces and key commitment aren't important. For comparison, an empty AES-GCM ciphertext is 16 bytes, while an empty Bessie ciphertext is 56 bytes. For a TLS-oriented cipher based on BLAKE3, see BLAKE3-AEAD.

Although the Bessie cipher and its library implementations are eventually intended for production use, the bessie CLI tool will always be for testing and demo purposes only. A general-purpose encryption CLI for real people needs to support public-key encryption and various ways of encoding and managing keys, neither of which are in scope for this project. If you are a real person and you need a general-purpose encryption CLI, consider age.

Usage

To install the bessie CLI tool, which is for testing and demo purposes only:

cargo install bessie_bin

Or to build and install from this repo:

cargo install --path rust/bin

To encrypt and decrypt a 1 MB file using the all-zero key (seriously, testing and demo purposes only):

head -c 1000000 /dev/urandom > myfile
bessie encrypt zero myfile myfile_enc
bessie decrypt zero myfile_enc myfile_copy
cmp myfile myfile_copy

To decrypt just the last byte of the encrypted file:

bessie decrypt zero myfile_enc myfile_last --seek=999999

To run tests for the whole project:

./test.py