Identification
Although the identification could seem to be useless because the system has to trust an untrusted party, it's critical to the security of the Authentication. In fact, the identification allows you to make the authentication problem a one-to-one problem, instead of a many-to-one problem, increasing its security by several orders of magnitude.
There are cases when it is acceptable to lower the security check a little bit, simplifying the identification phase to drastically reduce the amount of time needed for the process, making it less expensive. A typical example is badging to open a door. In this case, if you find a badge on the ground, you can enter without any problem since all the data is already present in the badge. On the other hand, if every time an employee's badge had to be identified by a security agent, you would see long lines of angry people waiting to be identified. In the badge example, the identification is usually done automatically, to make it quick enough...
