Social interaction is already a proven component of informal identification: humans are naturally skilled at recognizing other people and are unlikely to be duped by impersonation. Based on this premise, a fourth-factor, someone-you-know, has already been proposed as an emergency authentication method. This paper explores leveraging a user's preexisting social actions as a primary authentication tool, one that operates transparently and automatically without explicit user guidance. Specifically, we describe the feasibility of capturing a user's local social context using short range wireless devices and evaluate the uniqueness of that context in comparison to that of possible aggressors.