package chacha

README.md

ChaCha family of encryption functions, in OCaml

An OCaml implementation of ChaCha functions, both ChaCha20 and the reduced ChaCha8 and ChaCha12 functions. The hot loop is implemented in C for efficiency reasons.

Installation

opam install chacha

Usage

utop[0]> #require "mirage-crypto";;
utop[1]> #require "mirage-crypto-rng.unix";;
utop[2]> Mirage_crypto_rng_unix.initialize ();;
- : unit = ()
utop[3]> let key = Mirage_crypto_rng.generate 32;;
val key : Cstruct.t = {Cstruct.buffer = <abstr>; off = 0; len = 32}
utop[4]> let nonce = Cstruct.create 8;;
val nonce : Cstruct.t = {Cstruct.buffer = <abstr>; off = 0; len = 8}
utop[5]> #require "chacha";;
utop[6]> let state = Chacha.create key nonce;;
val state : Chacha.t = <abstr>
utop[7]> Chacha.encrypt (Cstruct.of_string "My secret text") state |> Cstruct.to_string;;
- : string = "\026m.\\363\\026\\263\\207Xg\\256l\\262\\232F"

• Key can either 32 (recommended) or 16 bytes

• Chacha state may use a different hashing function, the recommended Chacha_core.chacha20 is used by default.