lib-q-threshold-sig (PROVISIONAL)

lib-q-threshold-sig provides a provisional threshold signature flow for libQ.

• Construction style: hash-based, FROST-like threshold Schnorr flow.
• Hash/XOF: SHAKE256 from lib-q-sha3.
• Secret sharing: byte-wise Shamir shares over GF(256).
• Wire format: threshold_sig_wire_v1
[ver=1][profile=1][sig_len u16 LE][sig][meta_len u16 LE][meta].

Profile

The crate exposes ThresholdSigProfileV1:

• id = 1
• max_parties = 64

Proof size table

Measured from tests/vectors/manifest.json (KAT seed, profile v1, 3-of-5 sign path):

| Scenario | Bytes | Budget | Pass | |----------|------:|-------:|:----:| | Aggregated wire (threshold_sig_wire_v1) | 270 | 11264 | yes | | Profile v1 envelope lane | 270 | 8192 | yes |

Hard wire ceiling: WIRE_BUDGET_THRESHOLD_SIG_BYTES = 11264. Profile v1 envelope: PROFILE_ENVELOPE_BUDGET_BYTES = 8192.

KAT export

Schema: threshold-sig-kat-v1

cargo test -p lib-q-threshold-sig kat_regenerate_vectors -- --ignored

Output: tests/vectors/threshold-sig-pop-v1.json

Status

This crate is PROVISIONAL and intended for controlled evaluation. It is a pre-standard implementation intended for integration and protocol testing, not final production standardization.

Subresource integrity (SHA-384)

Paths in integrity-manifest.json are relative to the package root (including web/ and nodejs/ when both ship).