Security & Compliance

Goals

Keep the document conversion service safe and controllable across upload, conversion, and download stages, to protect the system and user data.

Input Safety

• Upload file size limit: MAX_FILE_SIZE (MB) to prevent resource abuse.
• Path and URL validation:
  • Prevent directory traversal (only allow controlled paths within the service).
  • When downloading remote files, validate http/https and restrict trusted sources to reduce SSRF risk.
  • URL-decode and re-validate parameters such as filename and url.

Data Safety

• File hash caching: reduce repeated conversions and resource consumption.
• Directory isolation: separate uploads and converted directories, and optionally partition by date.
• Logging: avoid logging sensitive values (such as database passwords).

Transport

• Prefer HTTPS, especially in production and for webhook callbacks.
• Add security headers (such as X-Content-Type-Options and X-Frame-Options) at a reverse proxy layer (for example, Nginx).

Rate Limiting and Concurrency

• Add rate limiting at the gateway/proxy layer (by IP/user).
• Consider queueing and concurrency control for large file conversions to reduce peak risk.

Webhook Security

• Use HTTPS callback URLs.
• Add request signing (for example, HMAC-SHA256) and include X-Signature in headers.
• Implement replay protection on the receiver side (use taskId for idempotency).

Dependency Security

• Regularly update NPM dependencies to patch known vulnerabilities.
• Mount font/resource directories as read-only where possible.

Logging and Auditing

• Use LOG_DIR to aggregate logs and record key events (uncaught exceptions, denied access, etc.).
• Follow data minimization and auditability principles to meet enterprise security requirements.