I think this may not be as difficult as it seems. What you have is just a function with a long complicated name, and similar for the three parameters.
The first line of the function is calling the openssl_cipher_iv_length function. This function is a standard part of the openssl php extension.
Without seeing more code I can't be sure, but I would guess it is about to open a Secure Socket (SSL = Secure Socket Layer), and send information somewhere, presumably copied from your server.
I've put two days in this quote just in case it turns out to be more complicated than I imagine, but I think it is just a one day job :-)
I love solving puzzles like this, would be delighted to do the job for you. If I can't figure it out I'm happy to forfeit the fee.
Thanks for taking the time to read my bid.
Ian