Further reading
The following are some useful resources to learn more about saving and loading data with Unity:
- Learn more about Unity Text Assets in the manual pages:
 
If you really want to get serious about game and web server security, then a proper API key strategy is probably the way to go. Here are some articles on sophisticated approaches to securing game data:
- Securing Unity Games with DexGuard and iXGuard from GuardSquare:
 - Creating API keys using Okta in PHP, published by Krasimir Hristozov:
 - How to Secure a PHP Based API Using JWT by Mauro Chojrin: