Biometric chain of provenance

A method for access control, the method comprising:

• receiving, via a mobile device, a user credential for use in performing access control;
• communicating a first signal between the mobile device and an audio unit of an access control device, the first signal comprising an audio signal;
• using the audio signal to determine a distance of the mobile device from the audio unit, and to distinguish the mobile device from another mobile device within an operating range of the access control device;
• and
• using the received user credential or an authentication result from the received user credential to perform the access control, responsive to the determined distance being within a predetermined range and responsive to the determination of the distance being performed within a predetermined time from receiving the user credential.

A system for access control, the system comprising:

• an access control server comprising at least one processor, the access control server configured to:
• receive, via a mobile device, a user credential for use in performing access control, wherein a first signal is communicated between the mobile device and an audio unit of an access control device, the first signal comprising an audio signal;
• use the audio signal to determine a distance of the mobile device from the audio unit, and to distinguish the mobile device from another mobile device within an operating range of the access control device;
• and
• use the received user credential or an authentication result from the received user credential to perform the access control, responsive to the determined distance being within a predetermined range and responsive to the determination of the distance being performed within a predetermined time from receiving the user credential.