Well, I'm shilling my noscrypt library :) full disclosure. But really the idea is performance and leaving the tricky binary stuff under the C barrier. From experience I found it quite difficult to implement cryptographic primitives natively in PHP. That being said, I'm interested in building an extension library wrapper for PHP and am sort of gauging interest.

Noscrypt handles of the encryption specs, signatures of course, and I'm currently working on utilities to completely handle nip04 and nip44 utf8 string encryption.