threshold/protocols/frost

FROST — Lux-Profile Threshold Schnorr

Tier B — Lux-profile + integration spec gap. Production implementation of FROST (Flexible Round-Optimized Schnorr Threshold) for the Lux ecosystem. Lux-profile submission package being assembled in this directory; readiness gated per SUBMISSION-STATUS.md.

What this is

FROST is a 2-round threshold-Schnorr signature scheme. Threshold-t of n parties produce a signature that verifies under the single-party Schnorr verifier for the configured ciphersuite. Used in the Lux ecosystem for:

• Cross-chain bridge custody (Cosmos Ed25519, Bitcoin Schnorr / Taproot)
• Account-abstracted multi-party wallets
• Validator-set threshold operations on non-PQ chains

Code location

Subdir	Content
frost.go	top-level orchestration
keygen/	distributed key generation
sign/	2-round threshold signing
frost_*_test.go	unit, math, suite, threshold, sr25519, fixed tests
frost_benchmark_test.go	benchmarks
scale_benchmark_test.go	committee-size scaling

Total: 20+ Go files, mature codebase.

Ciphersuites

The Lux profile pins two ciphersuites:

Ciphersuite	LP	Use case
FROST(Ed25519, SHA-512)	LP-4711	Cosmos / Solana / SR25519 chains
FROST(secp256k1, SHA-256, Taproot)	LP-4712	Bitcoin Schnorr / Taproot

See PARAMS.md for parameter-set details and threshold ranges.

Tier label

Tier B — Lux-profile + integration spec gap. Upstream IETF/CFRG draft (draft-irtf-cfrg-frost) is the construction; Lux adds the profile pinning + Lux-specific KAT manifest + integration with the threshold orchestration layer (internal/round, internal/party, pkg/protocol) and the LSS dynamic-resharing wrapper (lss/lss_frost.go).

Compare to siblings:

• luxfi/pulsar — Tier A (mechanized refinement vs FIPS 204)
• luxfi/corona — Tier B (no FIPS anchor, honest no-proof disclosure)
• protocols/frost (this) — Tier B (upstream IETF draft is construction, Lux profile gap)
• protocols/cmp — Tier B
• protocols/bls — Tier B

Dependencies

Dep	Role
luxfi/crypto/curve25519 (Ed25519 path)	underlying Ed25519 primitive
luxfi/crypto/secp256k1 (Taproot path)	underlying secp256k1 + Schnorr primitive
luxfi/threshold/internal/round	round-state machine
luxfi/threshold/internal/party	party-id ordering, validation
luxfi/threshold/internal/hash	domain-separated hashing per ciphersuite
luxfi/threshold/pkg/protocol	protocol type system

Consumed by

• luxfi/threshold/protocols/lss/lss_frost.go — LSS-FROST adapter (dynamic resharing)
• luxfi/mpc/ — production custody service
• luxfi/threshold/cmd/threshold-cli/ — CLI

Cross-references

• SPEC.md — construction spec + Lux profile
• SUBMISSION-STATUS.md — Tier B → A gating items
• PROOF-CLAIMS.md — honest scope (what's proved, what's not)
• TEST-VECTORS.md — KAT format + upstream CFRG vectors
• SECURITY.md — threat model + responsible disclosure
• PARAMS.md — ciphersuite + threshold range registry
• LP-4710 — FROST precompile
• LP-4711 — Ed25519 ciphersuite
• LP-4712 — secp256k1 Taproot
• LP-4700 — threshold-MPC family umbrella