Does anyone know of a self hosted web chat alternative to Rocket Chat?

Hello Guys, I need an alternative to RocketChat, I'm trying to implement a Chat that needs to be dockerized, open source, Web, with cryptography, LDAP e allows the creation of channels and rooms (a lot to ask?! I know). Sadly, I work in a Federal research Institute in Brazil, got no funds to acquire a paid version. The closest I got was Rocketchat version 3.18.7 and mongodb 4.0.18 (The database was not accepted, because it was not approved by the IT administrator) so back to the start. Tested a lot of options, but there's always something missing (or being charged) to attend the requisites. Accept any ideas. Thanks in advance.