Version:            (using KDE 4.1.3)
OS:                Linux
Installed from:    Ubuntu Packages

While user login kdm calls "pam_authenticate" _after_ prompting the user for name and/or password which contradicts the recommendation of the documentation (PAM ADG). It reads in chapter 2: "It is important to note that the application must leave all decisions about when to prompt the user at the discretion of the PAM library."

The current implemetation of kdm first prompts the user for his name and in some cases for his password and then it calls "pam_authenticate". This makes it impossible to use alternate authentication methods like smart cards or biometric processes to identify and/or authenticate a user.

The correct behavior would be to first call pam_authenticate and then await a callback from PAM's "conversation function" in case a "normal" authentication by keyboard is configured. That would make e.g. fingerprint login by PAM modules like "Fingerprint GUI" make possible in the same way they work with gdm.