Adds rate-limiting to prevent device enumeration attacks via rapid
subscription/disconnect cycles. Without this fix, an attacker could
enumerate ~120 bitchat devices per minute by connecting, subscribing,
capturing the announce packet, then disconnecting and moving to the next.
Key changes:
- Add per-central rate-limit tracking with exponential backoff
- Minimum 2-second interval between announces per central
- Exponential backoff (2x) up to 30 seconds for rapid reconnects
- After 5 rapid attempts, suppress announces entirely (likely attack)
- Clean up stale rate-limit entries after 60-second window
- Clear rate-limit state during panic mode
Configuration:
- bleSubscriptionRateLimitMinSeconds: 2.0
- bleSubscriptionRateLimitBackoffFactor: 2.0
- bleSubscriptionRateLimitMaxBackoffSeconds: 30.0
- bleSubscriptionRateLimitWindowSeconds: 60.0
- bleSubscriptionRateLimitMaxAttempts: 5
Security audit reference: Cure53 BCH-01-004 (Medium severity)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
