What is proof of presence?

Last reviewed 20 October 2026

Proof of presence is evidence that someone or something was at a place at a time; in digital systems it usually means proof of location for a device, which can be checked cryptographically, plus a separate control, such as identity verification, for who was holding it.

Two questions in one phrase

“Presence” bundles two questions: was a device there, and was a particular person with it. Device evidence can answer the first. The second needs a separate control. Octet calls the first proof of location.

• The device. A signed statement, produced on the device in secure hardware, that it was inside a region at a moment. See proof of location.
• The person. Identity verification, a biometric check, or a human witness. A location proof does not establish who held the phone.

Where the term is used

• Attendance and field work, where a worker checks in at a site.
• Events and access, where a ticket or credential is tied to being at the venue.
• Decentralised networks, where nodes claim to provide coverage at a location.
• Compliance, where a law applies to people in a place.

Making it hard to fake

The strongest device evidence is built on the device as a statistical proof from hundreds of inputs, from inertial sensors to radio signals, which must agree with each other over space and time. It is signed with a key the app cannot reach, and someone who trusts neither the user nor the vendor can check it. See device-attested location.