SECURITY

Cloudflare D1 Database Storage

All seals stored encrypted in Cloudflare D1 (SQLite at the edge) with triple-layer encryption. Encrypted blobs stored as base64 TEXT. Maximum 560KB per seal (due to D1 column limits).

Edge Runtime

All API routes run on Cloudflare Workers at the edge, providing low latency and DDoS protection.

Immutable Audit Logs

Every access attempt is logged with timestamps, IP addresses, and outcomes. Logs cannot be modified or deleted.

Encrypted Local Storage

Browser-based encrypted vault for saving seals. AES-GCM-256 encryption with unique key per browser. No server-side storage of user's vault links. Privacy-first design.

Simplified Security Model

Removed seed phrase complexity. Always uses cryptographically random keys. No recovery mechanism (by design). Users control what's stored via COPY | DOWNLOAD | SAVE buttons.

Replay Attack Prevention

Nonce-first validation prevents concurrent token reuse. Database-backed nonce storage ensures replay detection across all worker instances.

Atomic Database Updates

All-or-nothing pulse updates prevent inconsistent state. Single SQL operation ensures both timestamp and unlock time update together.

Strict Token Validation

Format validation rejects malformed pulse tokens before processing. Seal ID, timestamp, nonce, and signature all validated with regex.

Safe Deletion Order

Database-first deletion prevents data loss. If blob deletion fails, seal record is already gone (acceptable orphan).

Collision-Resistant Fingerprinting

SHA-256 hashed fingerprints for rate limiting. Combines IP + User-Agent + Accept-Language without truncation.

Memory Leak Protection

Automatic cleanup of concurrent request tracker at 10K entries. Zero-count entries removed first.

Accurate Access Metrics

Only counts successful unlocks, not locked checks. Provides accurate usage analytics.

File Size Enforcement

560KB limit (before encryption) enforced at all layers: UI validation, API validation, and database storage.

Zero-Knowledge Architecture

No user accounts, no passwords, no authentication. Security is enforced through cryptography alone. This eliminates credential theft, phishing, and password database breaches.

Time-Lock Enforcement

The server will not release Key B before the unlock time. Server-side validation using Date.now() prevents client-side time manipulation.

Rate Limiting with Fingerprinting

API endpoints use browser fingerprinting (IP + User-Agent + Language) with D1 database persistence. Rate limits survive across all worker instances. 10-20 requests per minute per fingerprint.

No Single Point of Failure

Split-key architecture means neither the server alone nor the client alone can decrypt content.

Triple-Layer Encrypted Storage

All seals encrypted with AES-GCM-256 client-side, Key B encrypted with master key server-side, and database encryption at rest. Zero plaintext storage.

Client-Side Decryption

Decryption happens in your browser. The server never sees the decrypted content.

CAPTCHA Protection

Turnstile CAPTCHA on seal creation prevents automated abuse and bot attacks.

Protected Against:

• Unauthorized early access (time-lock enforced server-side)
• Client-side time manipulation (server validates with Date.now())
• Server compromise (split-key architecture)
• Data tampering (AEAD encryption + database integrity)
• Brute force attacks (256-bit keys + fingerprinted rate limiting)
• IP rotation bypass (browser fingerprinting)
• Timing attacks (response jitter)
• Serverless state bypass (D1-backed rate limits and nonces)
• Automated abuse (Turnstile CAPTCHA)
• Replay attacks (nonce validation in D1 database)

Not Protected Against:

• Loss of vault link (Key A is in URL hash - treat like a password)
• Browser history/bookmark exposure (inherent to client-side crypto)
• Compromised recipient device after unlock
• Cloudflare infrastructure failure
• Quantum computing attacks (future threat)