Brainstorming with Grok on bitchat geohash DHT relay hopping:
Bitchat Relay Selection and Hopping Architecture Proposal
Objective: Enhance Bitchat’s relay selection for geohash channels with a deterministic, decentralized, and secure system that supports multi-level geohash granularity, time-slotted relay hopping, and DHT-based relay discovery. This improves privacy, reliability, fairness, and censorship resistance while ensuring seamless channel communication.
Architecture Overview:
1 DHT-Based Relay Discovery:
◦ Source: A Kademlia-based DHT (e.g., inspired by Fabric or HyperDHT) stores relay metadata (URL, IP, lat/long, uptime, NIP support). Relays announce signed entries (Nostr npub, PoW nonce for sybil resistance) under keys like hash("nostr-relay" + region). Clients query for geo-proximate relays dynamically.
◦ Anti-Spam: Normalize by IP+port+fingerprint (TLS cert hash); limit one entry per npub/day; require low-difficulty PoW (e.g., 16-bit SHA-256). Deduplicate by IP and flag multi-region claims via client-side filters (e.g., geo-mismatch with IP lookup via MaxMind GeoLite2).
◦ Fallback: Seed with a daily crawled list (from nostr.watch, hosted on IPFS/GitHub) for offline/bootstrap, updated in-app via DHT queries.
2 Geohash Granularity and Teleport Mechanism:
◦ Granularity: Support geohash levels: L=6 (neighborhood, ~150m), L=5 (city, ~5km), L=4 (region, ~150km), L=3 (state, ~5000km), L=2 (country, ~15,000km). Decode geohash to center lat/long (using geohash-js or equivalent).
◦ Selection Logic: For channel #bc_G (length L):
▪ Query DHT for relays; compute Haversine distance to G’s center.
▪ Filter viable relays within max distance (e.g., 1000km * (6-L+1)). If <5 viable, teleport: Truncate G to L-1, recompute center, retry up to L=2.
▪ Sort by distance, tiebreak by hash(URL). Pick top M=10 for hopping ring.
◦ Determinism: All clients converge on same M relays via shared geohash and DHT data.
3 Time-Slotted Relay Hopping:
◦ Mechanism: Rotate through M relays in 15-minute slots. Compute slot index: i = floor(unix_time / 900) % M. Select relay: ring[(hash(G) + i) % M]. Hash ensures per-channel uniqueness; modulo cycles fairly.
◦ Seamless Transition: At slot end, pre-verify next relay (ping, subscribe to #g-tagged events, check 90% event sync). Overlap subscriptions (1 min), publish to both, drop old post-sync. Fallback to next ring relay if verification fails.
◦ Fairness: Evenly distributes load (each relay ~1/M usage). Exclude overloaded relays (DHT-reported load>80%).
4 Implementation Details:
◦ Libraries: geohash-tools for decoding, Haversine for distance, Kademlia/HyperDHT for P2P discovery, Nostr client for event sync checks.
◦ Verification: Pre-hop, ping relay (WebSocket) and test NIP-01 subscription for recent #g events. Use Nostr event IDs for deduplication during overlap.
◦ Security: Signed DHT entries (Nostr npub) prevent spoofing. PoW and IP dedup thwart sybil attacks. Optional Bitcoin block height as slot seed enhances determinism.
◦ Performance: Cache relay lists per geohash (refresh every 6h). Limit M=10 for mobile efficiency. Battery-friendly: Hop only on active channel use.
Benefits:
• Privacy/Security: Hopping limits relay surveillance; ephemeral IDs stay intact; DHT avoids central points.
• Reliability: Teleport ensures sparse regions connect; verification skips bad relays.
• Fairness/Censorship Resistance: Even load distribution; fallback to broader regions bypasses local failures.
• Seamlessness: Overlap prevents event loss; deterministic logic ensures channel consistency.
Next Steps:
• Prototype: Simulate 100 relays, 10 geohashes (L=6 to 2), test hop success rate and sync.
• Beta: Integrate with existing selection; start with static list, add DHT incrementally.
• Community Input: Open-source DHT crawler (GitHub) for relay list contributions.
Effort: Extends existing geohash logic; ~2-3 weeks for DHT integration, 1 week for hopping. Minimal UI impact.
This proposal aligns with Nostr’s decentralized ethos and Bitchat’s ephemeral, geo-aware design, ready for dev evaluation and iterative rollout.
