ocaml-sodium

Ctypes bindings to libsodium 0.4.3+ which wraps NaCl. crypto_box and crypto_sign functions only right now.

module Crypto = Sodium.Make(Sodium.Serialize.String)
;;
let nonce = Crypto.box_read_nonce (Crypto.random Sodium.Box.(bytes.nonce)) in
let (pk, sk ) = Crypto.box_keypair () in
let (pk',sk') = Crypto.box_keypair () in
let c = Crypto.box sk pk' "Hello, Spooky World!" ~nonce in
let m = Crypto.box_open sk' pk c ~nonce in
print_endline (String.escaped (Crypto.box_write_ciphertext c));
print_endline m

Considerations

Originally described in The Security Impact of a New Cryptographic Library, NaCl is a high-level, performant cryptography library exposing a straightforward interface.

This binding has not been thoroughly and independently audited so your use case must be able to tolerate this uncertainty.

ocaml-sodium contains functors over serializations both for individual NaCl modules, e.g. Sodium.Box.Make, and as the Sodium.Make bundle.

Despite ocaml-sodium's thin interface on top of libsodium, it is still important to be mindful of security invariants. In particular, you should ensure that nonces used for cryptographic operations are never repeated with the same key set.

Tests

Both internal consistency tests and tests against the NaCl distribution, rather than libsodium, may be found in lib_test.

Salt

Salt is very important for the camel. It needs eight times as much salt as do cattle and sheep. A camel needs 1 kg of salt a week and it is advisable to leave salt with camels every week.

-- UN FAO Manual for Primary Animal Health Care Workers