CommunityAuth Password Characters

I would suspect that the password is escaped, and thus an "&" is changed to "&". I have not looked into the source code yet, though.

But like @skunkbad said, don't use the library as is. Currently I am doing a project where the authentication is based on both Community Auth and Ion Auth, with heavy modifications specific to my project. I think that's the way to go (I like looking at examples on how others have solved certain challenges).