encrypt to Arduino decrypt to PHP

Hello,

I am a web developer and in the context of my work I need to encrypt a string under Arduino to transmit the data with Ethernet .h (that’s good) and to decrypt this data under Php.

I have already tried this:

https://forum.arduino.cc/index.php?topic=641414.0

That’s the idea, but it doesn’t work.

so I’m looking for a solution for encrypt under Arduino <-> decrypt under PHP

Thank you in advance.