Module slh_dsa 

SLH-DSA: Stateless Hash-Based Digital Signature Standard (FIPS 205).

This crate provides a pure-Rust implementation of SLH-DSA (formerly known as SPHINCS+), a post-quantum digital signature scheme standardized in FIPS 205. SLH-DSA is purely hash-based: its security relies only on the properties of cryptographic hash functions, with no algebraic structure (lattices, codes, etc.) that could be exploited by quantum or classical algorithms beyond generic attacks.

Architecture

SLH-DSA is built from a hierarchy of hash-based primitives:

1. WOTS+ – A one-time signature scheme that signs a single n-byte message using hash chains (see wots, internal).
2. XMSS – An eXtended Merkle Signature Scheme that authenticates 2^h’ WOTS+ keys via a binary Merkle tree, producing a few-time signature (see xmss, internal).
3. Hypertree – A tree of XMSS trees stacked in d layers, giving a many-time signature scheme with a total tree height of h = d * h' (see hypertree, internal).
4. FORS – A Forest of Random Subsets, a few-time signature used to sign the message digest before passing it to the hypertree (see fors, internal).
5. SLH-DSA – The top-level scheme that combines FORS + Hypertree to produce a stateless, many-time signature (see slh, internal).

Supported parameter sets

This crate implements all six SHAKE-based parameter sets defined in FIPS 205 Section 11:

Type	128-bit	192-bit	256-bit
Small (s)	Shake128s	Shake192s	Shake256s
Fast (f)	Shake128f	Shake192f	Shake256f

The “s” variants produce smaller signatures; the “f” variants are faster to sign and verify.

Examples

use quantica::slh_dsa::{SlhDsa, Shake128f, OsRng};

// Generate a key pair
let mut rng = OsRng;
let (secret_key, public_key) = SlhDsa::<Shake128f>::keygen(&mut rng).unwrap();

// Sign a message (empty context string)
let message = b"hello, post-quantum world!";
let signature = SlhDsa::<Shake128f>::sign(message, b"", &secret_key, &mut rng).unwrap();

// Verify the signature
let valid = SlhDsa::<Shake128f>::verify(message, b"", &signature, &public_key).unwrap();
assert!(valid);

Re-exports

pub use crate::prehash::PreHash;

pub use params::Params;

pub use params::Sha2_128f;

pub use params::Sha2_128s;

pub use params::Sha2_192f;

pub use params::Sha2_192s;

pub use params::Sha2_256f;

pub use params::Sha2_256s;

pub use params::Shake128f;

pub use params::Shake128s;

pub use params::Shake192f;

pub use params::Shake192s;

pub use params::Shake256f;

pub use params::Shake256s;

pub use rng::CryptoRng;

pub use rng::OsRng;

Modules

params

SLH-DSA parameter set definitions and the Params trait. SLH-DSA parameter sets (FIPS 205, Section 11).

rng

Minimal cryptographic RNG trait and OS-backed implementation. Minimal cryptographic RNG trait and OS-backed implementation.

Structs

Signature

SLH-DSA signature. Type-tagged with P.

SigningKey

SLH-DSA signing key (secret key, 4 * P::N bytes).

SlhDsa

Generic SLH-DSA interface parameterized by parameter set (FIPS 205).

VerifyingKey

SLH-DSA verifying key (public key, 2 * P::N bytes).

Enums

SlhDsaError

Errors that can occur in SLH-DSA operations.