Cardea – Proof-of-Work Comment Spam Protection
Are you tired of anti-spam plugins that bloat your site, inject third-party tracking, or constantly upsell you on premium SaaS subscriptions? Are you looking for a straightforward, lightweight solution that just protects your comments without the extra baggage? Then Cardea is the right tool for you. Cardea is a radically simple, zero-dependency Proof-of-Work (PoW) comment spam protector. Developed transparently on GitHub as a purely open-source project, it does one thing and does it perfectly: it stops automated bot spam on native WordPress comments. Why Choose Cardea? Cardea offers distinct advantages for site owners who value simplicity, privacy, and performance: Hyper-Focused & Zero Bloat – Cardea is strictly dedicated to the native WordPress comment system. Unlike multi-purpose anti-spam plugins that inject heavy compatibility layers for various form builders and e-commerce platforms, Cardea remains extremely lightweight and performant—protecting only what you need protected. 100% Standalone & Sovereign – No external API keys. No commercial SaaS tiers. No phone-home telemetry. Cardea is entirely self-hosted and self-contained. Your comment protection never depends on a third-party service staying alive. Strict Privacy (GDPR Compliant) – Because the Proof-of-Work computation happens locally in each visitor’s browser, there are no tracking cookies, no user profiles, and no third-party data transfers. Unlike cloud-based CAPTCHA solutions, Cardea transmits nothing to external servers—making it inherently GDPR-friendly. Reduced Attack Surface – By doing one thing perfectly (protecting native comments), Cardea avoids the security vulnerabilities inherent in massive, multi-ecosystem integrations. A focused codebase means fewer CVEs and tighter security. Plug-and-Play Simplicity – No complex routing rules. No integration toggles. No configuration mazes. Users simply activate Cardea and their discussion threads are protected immediately. To view the source code, contribute, or report issues, visit the Cardea GitHub Repository. How It Works Challenge Generation: When a page with a comment form loads, the server generates a cryptographically signed challenge using HMAC-SHA256. No database write occurs at this stage. Client-Side Mining: When a user focuses on the comment textarea, a JavaScript Web Worker begins mining in the background. Solution Discovery: The worker repeatedly hashes the challenge string (nonce + timestamp + salt) with incrementing counter values until it finds a hash with the required number of leading zeros. Server Verification: On submission, the server first verifies the HMAC signature (ensuring the challenge wasn’t tampered with), then validates the PoW solution, and finally records the used signature in a capped, self-pruning replay store to prevent replay attacks. Features Zero Database Bloat on Load – Challenges are generated using stateless HMAC signatures, meaning the plugin requires exactly zero database writes when a visitor loads a page. Zero Dependencies – No external APIs or services required. Client-Side Mining – Heavy computation happens in the user’s browser using Web Workers. Deferred Execution – The cryptographic mining engine only spins up when a user interacts with the comment field, ensuring casual readers incur zero performance penalty. Self-Cleaning Replay Protection – Server-side state is only stored upon a successful comment submission to prevent bot replay attacks; expired entries are pruned automatically and the store is capped (1024 signatures). Server-Side Verification – Server verifies HMAC signature first, then performs SHA-256 PoW validation. Configurable Difficulty – Adjust the number of leading zeros required (1-8). Configurable Time Window – Set how long challenges remain valid (5-120 minutes). Non-Intrusive – Works transparently for legitimate users; spammers must complete the PoW challenge. WordPress Standards – Follows WordPress coding standards and best practices. Privacy First (GDPR Friendly) – No cookies, no user tracking, no CAPTCHA popups, and absolutely zero data sent to third-party cloud APIs. Smart Pathway Protection – Gates anonymous comment submission end to end: the comment form requires a solved Proof-of-Work challenge, and anonymous REST comment creation is already rejected by WordPress core (401) — Cardea additionally applies the same PoW check to any REST comment creation core permits, as a defense-in-depth layer. Native Trackbacks/Pingbacks and authenticated requests are allowed. Page Caching Compatible – Uses dynamic REST API endpoint to fetch fresh challenges, ensuring compatibility with edge caching (Cloudflare, Varnish) and full-page caching plugins. Logged-In User Bypass – Skips PoW challenge for authenticated users, eliminating unnecessary CPU usage on the frontend. Architecture & Testing Cardea is built with an enterprise-grade engineering stack focused on reliability and performance: Frontend Architecture: * Zero-dependency JavaScript using native Web Crypto APIs (crypto.subtle) * Web Workers for background cryptographic mining (non-blocking UI) * Dynamic challenge fetching via REST API (compatible with page caching) * Skip PoW for logged-in users (zero CPU overhead for authenticated commenters) Backend Architecture: * Localized replay protection via a capped replay store (single option, no per-token rows) * Self-pruning: expired entries are cleared automatically on write (no cron dependency) * Single verification pass: signature check + PoW validation * Single-use tokens: a challenge can be redeemed exactly once, which bounds any interception-style attack to a single comment (standard one-shot-token semantics) Testing Stack: * PHPUnit – Backend logic verification (HMAC generation, challenge validation, replay prevention) * Jest – Cryptographic worker validation (difficulty checking, solution finding, message interface) * Playwright – End-to-End browser testing integrated with WordPress Playground (full WordPress environment) This comprehensive testing approach ensures the plugin handles legitimate users seamlessly while actively blocking sophisticated bot attacks. Developer Rigor Cardea is built with an enterprise-grade engineering stack focused on reliability and performance: Architecture: * Zero Database Bloat on Load – Stateless HMAC signatures ensure zero database writes on page load * Self-Cleaning Replay Protection – Uses a capped replay store that prunes expired entries automatically * Deferred Execution – Mining only starts when user interacts with comment field Testing Stack: * PHPUnit – Backend logic verification (HMAC generation, challenge validation, replay prevention) * Jest – Cryptographic worker validation (difficulty checking, solution finding, message interface) * Playwright – End-to-End browser testing integrated with WordPress Playground (full WordPress environment) Cross-Theme Compatibility: * Uses HTMLFormElement.prototype.submit.call() to bypass DOM clobbering issues * Graceful fallback for browsers without Web Worker support
Limit Login Attempts (Spam Protection)
Limit the number of login attempts possible both through normal login as well as using auth cookies. By default WordPress allows unlimited login attempts either through the login page or by sending special cookies. This allows passwords (or hashes) to be brute-force cracked with relative ease. Limit Login Attempts blocks an Internet address from making further attempts after a specified limit on retries is reached, making a brute-force attack difficult or impossible. Basic Features Limit the number of retry attempts when logging in. Configurable lockout timings. Email notification of blocked attempts (Detailed email containing all necessary information). Notify the user of remaining attempts. Report containing all blocked attempts. Whitelist/Blocklist of IPs (Support IP ranges). Allow/Block Countries. Automatically block IP addresses that exceed limit login attempts Automatically add IP addresses that exceed blocks limit to the deny list Send notifications about blocked retry (Email sent to admins) Inform the user about the remaining retries or lockout time on the login page. Unlock The Locked users – Easily unlock the locked admin through the email or dashboard. Limit the number of retry attempts when logging in per IP. Limit the number of attempts to log in using cookies. Optional logging and optional email notification. Compatible with Google captcha, Captcha Plus & reCaptcha. Dashboard gives you an overview of your site’s security. Enable or disable the plugin functionality Enable to disable email notifications Compatible with latest WordPress version Woocommerce login page protection. Wordfence & Sucuri compatibility. GDPR compliant. Advanced Features (PRO) All Basic features included. Save the password that was used by the hacker (Save part of the password and hide the last three digits). Advanced dashboard gives you an overview of your site’s security (Charts for the most important reports). Block attackers by IP, Country, IP range. Mobile Application for the admins to follow up the site security (Download APK). Video Description Plugin Settings and Reports
