Module safe_api 

High-level safe Rust SDK for FN-DSA (FIPS 206) post-quantum digital signatures.

FN-DSA (FFT over NTRU-Lattice-Based Digital Signature Algorithm) is the NIST standardization of the Falcon signature scheme as FIPS 206.

Quick Start

use falcon::safe_api::{FnDsaKeyPair, FnDsaSignature, DomainSeparation};

let kp = FnDsaKeyPair::generate(9).unwrap();
let sig = kp.sign(b"Hello, post-quantum world!", &DomainSeparation::None).unwrap();
FnDsaSignature::verify(sig.to_bytes(), kp.public_key(), b"Hello, post-quantum world!", &DomainSeparation::None).unwrap();

Domain Separation (FIPS 206 §6)

FIPS 206 defines two signing modes:

• FN-DSA (ph_flag = 0x00) — pure signing; the raw message is hashed inside the algorithm. Use DomainSeparation::None or DomainSeparation::Context for optional domain binding.

• HashFN-DSA (ph_flag = 0x01) — hash-and-sign; the message is pre-hashed with SHA-256 or SHA-512 before signing. Use DomainSeparation::Prehashed with a PreHashAlgorithm selector.

let kp = FnDsaKeyPair::generate(9).unwrap();

// Pure FN-DSA with an application context string
let ctx = DomainSeparation::Context(b"my-protocol-v1");
let sig = kp.sign(b"msg", &ctx).unwrap();
FnDsaSignature::verify(sig.to_bytes(), kp.public_key(), b"msg", &ctx).unwrap();

// HashFN-DSA (pre-hash with SHA-256)
let ph = DomainSeparation::Prehashed { alg: PreHashAlgorithm::Sha256, context: b"" };
let sig2 = kp.sign(b"msg", &ph).unwrap();
FnDsaSignature::verify(sig2.to_bytes(), kp.public_key(), b"msg", &ph).unwrap();

Security Levels

logn	Variant	NIST Level	Private Key	Public Key	Signature
9	FN-DSA-512	I	1281 B	897 B	666 B
10	FN-DSA-1024	V	2305 B	1793 B	1280 B

Structs

FnDsaExpandedKey

A precomputed Falcon signing tree for fast repeated signing.

FnDsaKeyPair

An FN-DSA key pair (private key + public key).

FnDsaSignature

An FN-DSA / HashFN-DSA digital signature.

Enums

DomainSeparation

Domain separation context for FN-DSA / HashFN-DSA (FIPS 206 §6).

FalconError

Errors returned by the FN-DSA API.

PreHashAlgorithm

Pre-hash algorithm selector for HashFN-DSA (FIPS 206 §6.2).

Type Aliases

FalconKeyPair

Type alias for backward compatibility.

FalconSignature

Type alias for backward compatibility.