[vxfemboy]

Closes #39.

Overview

Implements an online, decentralized hBcof-$ threshold Certificate Authority (CA) using RFC 9591 Flexible Round-Optimized Schnorr Threshold (FROST) signatures over Ed25519 (frost-ed25519 v3.0.0), coexisting seamlessly alongside the existing offline single-key CA model.

Because FROST aggregates linearly into a standard 64-byte Ed25519 signature, all credentials emitted by the threshold CA are wire-format and byte-for-byte identical to single-signer certificates. Existing verifiers in crates/yip-membership, bin/yipd, and bin/yip-rendezvous require zero wire changes.

Key Architectural Enhancements

1. RFC 9591 FROST(Ed25519, SHA-512) Ciphersuite & Interactive DKG:
   • dealer_generate and interactive 3-round Distributed Key Generation (DKG) without a trusted dealer (bin/yip-ca/src/threshold/dkg.rs).
2. Proactive Share Refresh & Lost Share Repair (CVE-2025-58359 Hardened):
   • Zero-knowledge polynomial refresh maintaining identical group verifying key across epochs while invalidating historical compromised shares.
   • Guarded against CVE-2025-58359 threshold-drift vulnerabilities.
3. Single-Round (1-RTT) Online Enrollment:
   • Preprocessed commitment pools (frost::round1::preprocess) pre-cached at the coordinator collapse online signing from two network round-trips to a single round-trip.
4. ROAST Asynchronous Coordination:
   • Robust Asynchronous Schnorr Threshold state machine guarantees liveness and eliminates stalls from up to - t$ unresponsive, slow, or Byzantine signers with identifiable aborts (verify_signature_share).
5. Rollback-Immune Nonce Vault:
   • Ephemeral nonce management (EphemeralNonceVault) bound to monotonic 128-bit CSPRNG boot_epoch_id and atomic single-use consumption (take_once) to eliminate nonce-reuse private key extraction under VM snapshots.
6. Daemon Network Architecture & Automated Background Rotation:
   • yip-ca serve --role coordinator and --role signer.
   • yip-ca enroll client utility.
   • yipd background monitoring with automated certificate renewal at $\ge 70%$ of TTL.
   • UNIX control socket commands: yipd cert status and yipd cert renew.
7. End-to-End Verification:
   • 20 unit/integration tests in yip-ca.
   • renewal_test.rs in yipd.
   • run-netns-threshold-ca.sh end-to-end multi-namespace bridge integration test.