8 releases

0.3.1 May 12, 2021
0.3.0 Nov 2, 2020
0.2.4 May 16, 2020
0.2.3 Oct 21, 2019
0.1.0 Feb 3, 2019

#42 in Cryptography

Download history 13667/week @ 2021-02-26 13057/week @ 2021-03-05 12495/week @ 2021-03-12 11724/week @ 2021-03-19 11306/week @ 2021-03-26 10128/week @ 2021-04-02 12965/week @ 2021-04-09 11571/week @ 2021-04-16 11524/week @ 2021-04-23 11414/week @ 2021-04-30 11555/week @ 2021-05-07 11178/week @ 2021-05-14 11322/week @ 2021-05-21 9636/week @ 2021-05-28 9846/week @ 2021-06-04 8391/week @ 2021-06-11

51,560 downloads per month
Used in 26 crates (5 directly)

MIT/Apache

135KB
3.5K SLoC

The ChaCha family of stream ciphers

Features

  • pure Rust implementation
  • supports the RustCrypto API
  • builds on stable Rust
  • portable
  • fast: within 15% of throughput of a hand-optimized ASM SIMD implementation (floodberry/chacha-opt) on my machine (a Xeon X5650, using ppv-lite86)
  • no-std compatible (std required only for runtime algorithm selection)

Supported Variants

ChaCha20: used in chacha20-poly1305 in TLS, OpenSSH; arc4random in the BSDs, Linux /dev/urandom since 4.8.

Ietf: IETF RFC 7539. Longer nonce, short block counter.

XChaCha20: constructed analogously to XSalsa20; a mixing step during initialization allows using a long nonce and along with a full-sized block counter.

ChaCha12, ChaCha8: faster; lower security margin of safety.


lib.rs:

Pure Rust ChaCha with SIMD optimizations.

Stream-cipher usage:

extern crate c2_chacha;

use c2_chacha::stream_cipher::{NewStreamCipher, SyncStreamCipher, SyncStreamCipherSeek};
use c2_chacha::{ChaCha20, ChaCha12};

let key = b"very secret key-the most secret.";
let iv = b"my nonce";
let plaintext = b"The quick brown fox jumps over the lazy dog.";

let mut buffer = plaintext.to_vec();
// create cipher instance
let mut cipher = ChaCha20::new_var(key, iv).unwrap();
// apply keystream (encrypt)
cipher.apply_keystream(&mut buffer);
// and decrypt it back
cipher.seek(0);
cipher.apply_keystream(&mut buffer);
// stream ciphers can be used with streaming messages
let mut cipher = ChaCha12::new_var(key, iv).unwrap();
for chunk in buffer.chunks_mut(3) {
    cipher.apply_keystream(chunk);
}

Dependencies