Autonomous and secure CAPTCHA plugin for Flatboard 5. Bot protection without third-party services, based on math and logic questions signed with HMAC-SHA256.

Features

• Math and logic questions generated dynamically (addition, subtraction, multiplication, missing number, general knowledge)
• HMAC-SHA256 signed token (anti-forgery and anti-replay protection)
• Minimum submit time check (timing-based bot detection)
• Server-side blocking, lightweight client-side validation
• AJAX/REST communication (compatible with standard Flatboard forms)
• Admin dashboard with:
  • HMAC secret key management (cryptographic key generation, masked display, one-click save)
  • Monthly bot-block statistics since plugin activation
  • Breakdown by context (registration, login, new topic, reply) and by block reason
• 2FA exemption — members who have enabled Flatboard's two-factor authentication (TOTP) can be automatically exempt from the CAPTCHA (configurable)
• Multilingual: French, English, German, Portuguese, Chinese
• 100% self-hosted — no external dependency