HTTPS in transit
Production installation requires HTTPS so customer sessions, API calls and uploads travel over encrypted connections.
Protection designed around customer control
Local-first PDF creation, encrypted cloud storage, signed billing events and permanent deletion controls work together to reduce unnecessary exposure.
AES-256-GCM at rest
The server encrypts uploaded PDFs with authenticated encryption before writing the backup file.
Protected credentials
Passwords and gift-card PINs use password hashing. API tokens and card codes use one-way hashes for lookup.
Deletion controls
Customers can remove individual cloud PDFs or permanently delete their account and stored files.
Important deployment responsibilities
Security also depends on the server operator. Keep PHP and MySQL patched, protect the application key and Stripe secrets, restrict filesystem access, retain appropriate backups, monitor the audit log, and publish privacy/retention terms that match your actual operation.
The app handles highly sensitive message content. Complete Google Play SMS permission review, provide a truthful privacy disclosure, test deletion, and obtain local legal advice before accepting customers.