Searching for encryption C++ Library

Hello there,

unfortunately, I don't know much about encryption so I don't know what algorithm I need.

I'm searching for a library that is able to do asymmetric encryption in C++ on binary data (~50 megabytes).

It should be able to decrypt with the public key, but encrypt with the private one. So that I'm the only one to provide (encrypted) data that others can use if they decrypt it using their public key.

Maybe someone could point me into the right direction?

Many thanks in advance,