Custom Authentication with username and password

First of all I would like to thank all contributors for their work on Parse.

We want to include a username/password based login strategy as custom authentication. Therefore we want to use an existing database and replace the default login with a custom authentication. Users should log in as usual with their username/password, in the background the password of the existing database should be checked for a user who has already logged in to Parse, and for a user who has not yet logged in to Parse a new Parse user should be created, whose data (username, name and email) is filled with those from the existing database.

The first problem is that with a custom authentication of Parse, the login data (especially the password) are stored in plain text in the “authData” field of the user. The second problem is that from the Custom Authentication Provider we do not have the possibility to provide more user data than the one the user enters for login.

We could handle the entire process via CloudCode or solve it completely outside of Parse. However, this does not sound like a clean solution to us. Is there a way to solve the problem that we overlooked?