Post-Quantum Trigger Signer (ML-DSA-65)

SPDX-License-Identifier: AGPL-3.0-or-later

scpn_quantum_control.crypto.ml_dsa is a from-specification implementation of the FIPS 204 ML-DSA-65 module-lattice digital signature scheme, and scpn_quantum_control.crypto.pqc_trigger builds a capacitor-bank trigger authorisation signer on top of it.

This is FIPS 204-conformant — it reproduces the official NIST ACVP known-answer vectors (keyGen, deterministic sigGen, sigVer) bit for bit — but it is not a FIPS-140-validated cryptographic module and offers no side-channel-resistance guarantee. It authorises the discharge command that precedes trigger arming; it does not sit on the sub-50 ns combinatorial path.

ML-DSA-65

The polynomial ring is R_q = Z_q[X]/(X^256 + 1) with q = 8380417. Parameters (FIPS 204 Table 1): (k, l) = (6, 5), eta = 4, gamma1 = 2^19, gamma2 = (q-1)/32, tau = 49, omega = 55, d = 13, lambda = 192. Public key 1952 B, secret key 4032 B, signature 3309 B.

from scpn_quantum_control.crypto import ml_dsa

pair = ml_dsa.key_gen(seed)                      # 32-byte seed -> key pair
sig = ml_dsa.sign(pair.secret_key, message, context=b"ctx")
assert ml_dsa.verify(pair.public_key, message, sig, context=b"ctx")

Conformance is asserted in tests/test_ml_dsa_pqc.py against the NIST ACVP vectors in tests/data/ml_dsa_65_kat.json.

Trigger signer

PqcTriggerSigner binds the payload to a timestamp inside the signed message, so neither can be altered without invalidating the signature; verification optionally enforces a freshness window.

from scpn_quantum_control.crypto.pqc_trigger import PqcTriggerSigner

signer = PqcTriggerSigner()
pk, sk = signer.keygen()
sig = signer.sign_capacitor_bank_trigger("pulse-001", 24_500.0, timestamp_ns, sk)
# verify within a 10 ms freshness window:
ok = signer.verify(payload, sig, pk, max_age_ns=10_000_000)

Acceleration

The negacyclic NTT (the dominant lattice operation) dispatches to a Rust kernel that is bit-true (exact integer) with the Python reference; the rejection loop, sampling, and encoding stay in Python.

Measured (release build, median of 21, scripts/bench_ml_dsa.py, results/ml_dsa_benchmark.json, functional_non_isolated):

operation	time
NTT (Python)	209.7 µs
NTT (Rust)	12.9 µs (16.2×)
key generation	17.7 ms
signing	27.5 ms
verification	10.8 ms

The millisecond-scale signing/verification latency is appropriate for the authorisation gate, which precedes — and is not on — the fast trigger path.

Consumers

SCPN-MIF-CORE imports PqcTriggerSigner to sign capacitor-bank discharge commands prior to arming the combinatorial trigger.