@hackage / quantex

post-quantum cryptography for Haskell
type-safe C bindings to the NIST standards

quantex covers the NIST post-quantum standards ML-KEM, ML-DSA, and SLH-DSA, plus the X-Wing hybrid KEM. Behind them are upstream C reference implementations (mlkem-native, mldsa-native, slhdsa-c, and Monocypher for X25519), wrapped in a pure, phantom-typed API.

Highlights

• Phantom-typed PublicKey a, SecretKey a, Ciphertext a, Signature a. Mixing schemes does not compile.
• Pure Either QuantexError API. No exceptions in pure code.
• Deterministic seed-based core, with IO wrappers over a minimal platform entropy shim (no third-party entropy dependency).
• Secret keys, seeds, and shared secrets live in zeroizing, page-locked storage with constant-time equality and no Show.
• Every primitive is a vendored C reference implementation, pinned by commit.

Install

From Hackage

cabal install quantex

Or add quantex ^>=0.1 to your package's build-depends. The library pulls only base, bytestring, and deepseq, and is tested with GHC 9.10, 9.12, and 9.14.

From a GitHub release

Download quantex-<version>.tar.gz from the releases page and install the tarball directly:

cabal install quantex-<version>.tar.gz

From source

Point a cabal.project at the repository:

source-repository-package
  type: git
  location: https://github.com/d3z-the-dev/quantex
  subdir: quantex

Then add quantex to your build-depends.

Quickstart

Key encapsulation. Any scheme is one type application away:

{-# LANGUAGE TypeApplications #-}

import Quantex.KEM (decaps, encaps, keypair, sharedSecretEq)
import Quantex.KEM.MLKEM (MLKEM768)
-- or: import Quantex.KEM.XWing (XWing)

main :: IO ()
main = do
  (public, secret) <- keypair @MLKEM768
  (encapsulated, shared) <- encaps public
  print (sharedSecretEq shared (decaps secret encapsulated))

Signing, hedged by default per FIPS 204/205:

{-# LANGUAGE OverloadedStrings, TypeApplications #-}

import Quantex.Sign (contextEmpty, keypair, sign, verify)
import Quantex.Sign.MLDSA (MLDSA65)

main :: IO ()
main = do
  (public, secret) <- keypair @MLDSA65
  signed <- sign secret contextEmpty "attack at dawn"
  print (verify public contextEmpty "attack at dawn" signed)  -- Right ()

API at a glance

More usage

Prehash signing (HashML-DSA, FIPS 204 §5.4; HashSLH-DSA, FIPS 205 §10.2) hashes the message first. It is domain-separated from pure signing, so the two never cross-verify. Use signPrehashed/verifyPrehashed for a whole message, or signDigest/verifyDigest for a Digest computed elsewhere (for example over a streamed file that never fits in memory):

import Quantex.Sign (contextEmpty, keypair, signPrehashed, verifyPrehashed)
import Quantex.Sign.MLDSA (MLDSA65)
import Quantex.Sign.Prehash (PrehashAlgorithm (SHA2_256))

main :: IO ()
main = do
  (public, secret) <- keypair @MLDSA65
  signed <- signPrehashed secret contextEmpty SHA2_256 "attack at dawn"
  print (verifyPrehashed public contextEmpty SHA2_256 "attack at dawn" signed)  -- Right ()

Every operation has a deterministic form (keypairFrom, encapsFrom, signFrom, signDeterministic) over validated seeds, so no hidden randomness enters the core. Serialization is raw encode/decode with strict length validation on decode:

import Quantex.Codec (decode, encode)

decode (encode public) == Right public

For an ML-KEM secret key, store the 64-byte generation seed instead of the expanded decapsulation key: it is smaller and is the FIPS 203 canonical form. Persist seedBytes and rebuild with secretKeyFromSeed on load.

[!IMPORTANT] secretKeyBytes, seedBytes, and sharedSecretBytes copy secrets into ordinary, non-zeroizing memory. Treat every such copy as radioactive and keep it under the same protection as the key. Codec covers only public-material types, so encode/decode never crosses this boundary implicitly. To consume a secret without crossing it at all, use withSecretKey and withSharedSecret: they lend the raw zeroizing buffer to a callback, so a KDF or AEAD key never materializes an unzeroized copy. See SECURITY.md.

Examples

Ten self-contained programs, one per application domain: secure transport, file and message encryption, firmware and release signing, IoT provisioning, key escrow, and bearer tokens. Each reads top to bottom as one realistic scenario, prints a narrated transcript, and exits non-zero on any deviation, so the set doubles as a smoke test.

They ship in the repository, not in the published package. See examples/ for the full matrix of executables, schemes, and what each one demonstrates.

Design

• Cryptographic math is never implemented in Haskell. Every primitive call crosses the FFI into vendored C: mlkem-native (ML-KEM), mldsa-native (ML-DSA), slhdsa-c (SLH-DSA), Monocypher (X25519 inside X-Wing). Upstream commits and local patches are recorded in quantex/cbits/README.md.
• Phantom types carry the scheme, so keys and ciphertexts of different schemes never mix.
• The core is deterministic over seeds. IO wrappers add entropy at the edge.
• Secret material carries no Show; public material shows byte counts only, and nothing serializes implicitly.

Security

[!WARNING] Constant-time and side-channel resistance are inherited from the vendored C, not established by this library. mlkem-native, mldsa-native, and slhdsa-c avoid secret-dependent branches by construction but are not hardened against microarchitectural attacks; Monocypher documents constant-time X25519. Zero-on-GC is best-effort. quantex is pre-release.

On top of the upstream primitives, the wrapper adds no secret-dependent branching, constant-time secret equality, zeroizing and page-locked storage from the moment a secret is created, and strict length plus FIPS 203 §7.2/§7.3 key checks at every decode boundary. Full threat model, zeroization details, and the reporting process live in SECURITY.md; known-answer test vectors are pinned and documented in quantex/test/vectors/README.md.

Status

[!NOTE] Pre-release, API under construction. Serialization is raw encode/decode with strict length validation in Quantex.Codec. DER and OID encodings are out of scope for v0.1.

License

BSD-3-Clause; see LICENSE. Vendored C keeps its upstream licenses; see quantex/LICENSE.third-party.