Magnetar — Public-DKG MPC Threshold SLH-DSA (research profile)

Tier 3 of the Hanzo PQ Threshold Suite. Research-track construction for threshold FIPS 205 SLH-DSA via MPC. NOT production-ready. NOT part of the v0.1 NIST MPTC submission.

What this document is

A placeholder + design-direction sketch for a future research-grade public-DKG threshold construction over FIPS 205 SLH-DSA. The Hanzo PQ Threshold Suite includes Magnetar to signal architectural intent without overclaiming maturity.

What this document is NOT

Not a specification. The protocol is unfixed.
Not a security claim. The protocol has not been analyzed.
Not an implementation. No ref/go/-equivalent exists for Magnetar.
Not a NIST submission. Submitting threshold SLH-DSA as if it were standardized would be inaccurate.

Why Magnetar exists conceptually

SLH-DSA is hash-based and stateless (FIPS 205). Its security rests on different assumptions from ML-DSA: collision/preimage resistance of the underlying hash (SHA-2 or SHAKE), with no lattice assumption.

A threshold profile of SLH-DSA gives a defense-in-depth signature: even if ML-DSA's lattice assumption is broken in the future, Magnetar's hash-based threshold provides a fallback.

Why this is hard

Unlike threshold schemes for discrete-log-style or lattice-based signatures, SLH-DSA does NOT decompose into a linear-aggregation identity. The signing process is a tree of hash computations (Merkle tree of hash-based one-time signatures), where the "secret" is a SHAKE seed and "signing" involves traversing the tree based on the message hash.

Threshold SLH-DSA constructions in the literature typically require:

MPC over hash computations (slow; SHAKE computed inside MPC).
Distributed seed generation with VSS.
Per-signature MPC ceremony.

None of these match the elegance of FROST-style aggregation that Pulsar uses for ML-DSA. Magnetar is a research-grade direction, not an obvious specification target.

Suggested research direction

Distributed seed generation: Lux-style Pedersen-VSS over the SHAKE seed space (32 or 64 bytes for FIPS 205 SHAKE profiles).
Per-signature MPC: a multi-party Generic-Group-Model ceremony to compute the SLH-DSA signature components without any single party reconstructing the seed.
Hash precomputation amortization: precompute layers of the FORS / W-OTS+ Merkle tree in batched MPC sessions to amortize the per-signature ceremony cost.
Identifiable abort: same TLV-encoded evidence format as Pulsar §10, with per-MPC-round per-party state.
Public-key preservation across resharing: standard zero-secret-refresh applied to the SHAKE seed shares.

Parameter-set candidates

If the research direction matures into a specification, the following parameter sets are candidates (matching FIPS 205 §4):

Identifier	NIST Category	sig bytes	Notes
`MAGNETAR-THRESHOLD-SLH-DSA-SHAKE-128s`	1	7856	small/slow
`MAGNETAR-THRESHOLD-SLH-DSA-SHAKE-192s`	3	16224	RECOMMENDED if Magnetar matures
`MAGNETAR-THRESHOLD-SLH-DSA-SHAKE-256s`	5	29792	high security

Note that SLH-DSA signatures are LARGE compared to ML-DSA (7-30 KB vs 2-5 KB). The per-signature MPC cost will dominate deployment economics.

Why we do not ship Magnetar in v0.1

No mature construction: published threshold-SLH-DSA work is limited and not well-reviewed.
MPC complexity: per-signature MPC dwarfs the per-signature cost of Pulsar.
Signature size: 7-30 KB per signature is operationally expensive on-chain.
Standardization status: NIST has not signalled threshold SLH-DSA as a near-term MPTC target.

Magnetar will be re-evaluated for v0.2-v0.4 submission consideration based on community / NIST direction.

Honest framing for users

Magnetar is the research-track member of the Hanzo PQ Threshold Suite. It is intended for paranoid scenarios where ML-DSA's lattice security assumption is broken in the future and a hash-based fallback is needed. It is NOT recommended for production use today. Use Pulsar (Tier 1) for production threshold post-quantum signing.

Contact

For research collaboration on Magnetar:

Email: magnetar@lux.network
Public discussion: https://github.com/luxfi/pulsar/discussions (label: magnetar)

Document metadata

Name: docs/magnetar.md
Version: v0.1 (placeholder)
Date: 2026-05-18
Status: Research direction, not specification. No production use. No NIST submission claim.

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