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

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