This is what I've been busy with this weekend while sick at home instead of having fun at a conference ๐
A decade ago it was possible to use secp256k1 from PHP code, but the native binding is unmaintained beyond repair. Here's a new one that works.

GitHub
GitHub - 1ma/secp256k1-php: PHP bindings for libsecp256k1
PHP bindings for libsecp256k1. Contribute to 1ma/secp256k1-php development by creating an account on GitHub.

