I play MC like that, You can use mods to implement a type of login where players have to make a password for their name and have to login with it each time they connect. this wouldn’t help with players joining with different names as ban evasion but no one could pretend to be another player without their password.

I had it on my computer. Note that its not a .exe but a .jar file. You will need java installed before you can run it. minecraft.jar