Using a unique username and a complicated password is one possible method to verify that a user is who they say they are. What type of goal is this?

Answer:

Data Authenticity

Explanation:

Data authenticity is the quality of a data being genuine and not corrupted from the original.

In data security, this is used to ascertain (proof) an identity.

Exchange of information is always important in our day to day activities and every source of information needs to be known beyond reasonable doubts.

So, the goal of having a unique username without passwords is just not enough because usernames are always visible (or not difficult to trace) on every accounts; hence, the need for a password.

Data Authenticity is to have assurance that an action, a message, a transaction, an activity, or other exchange of information is from the source it claims to be.