I'm working on an iOS chat project using Firebase RealTime Database.
I want to use asymmetric cryptography for the management of messages between two users ..
Browsing the net I found an excellent library Themis and for security reasons, in the documentation, advised not to save the public keys in the database but instead recommended to save public keys using a mediation service such as keybase.io.
This is very difficult for me to understand ... has anyone had experience with keybase.io or with other services?
can you suggest me some understandable ways to save the public keys with PKI avoiding the database?