Threshold Signature
Definition
A threshold signature requires a minimum number of parties (threshold) from a larger group to cooperatively produce a valid signature. Unlike multi-signature, the result is a single signature indistinguishable from a regular one. Post-quantum threshold schemes use lattice or hash-based constructions.
Technical Explanation
Threshold mechanics: n parties, t+1 threshold (t can be compromised). Key shares distributed so any t+1 can sign; fewer cannot. Signature appears as single signature on-chain—no special verification. Distributed key generation (DKG) creates shares without trusted dealer.
Post-quantum threshold: FROST (Schnorr-based) is quantum-vulnerable. Research active on lattice-based (Dilithium) and hash-based (SPHINCS+) threshold schemes. More complex than classical threshold due to larger shares and different algebraic structures.
SynX Relevance
SynX supports threshold signature schemes for institutional custody and bridge security. Multiple parties share key material; signing requires cooperation without revealing complete keys. Quantum-resistant threshold signatures provide future-proof shared custody.
Frequently Asked Questions
- What's the difference from multi-sig?
- Threshold: one on-chain signature, smaller transaction. Multi-sig: multiple signatures visible on-chain.
- How are key shares created?
- Distributed key generation—parties jointly create shares without anyone seeing the complete key.
- Are threshold signatures quantum-resistant?
- Depends on underlying algorithm. FROST (Schnorr) is vulnerable. Lattice/hash-based thresholds are resistant.
Quantum-resistant shared custody. Threshold security with SynX