Proof-of-Play

Proof-of-play (PoP) is a cryptographically-signed log entry attesting that a specific creative played on a specific screen at a specific time. The entry contains: the creative ID, the screen ID, the playout timestamp, the duration actually played, and an Ed25519 signature over the whole bundle using the screen's private key. The signature lets any verifier confirm — without trusting Trillboards — that the playout came from the claimed screen and hasn't been tampered with.

Trillboards' PoP implementation is documented at /support/developers/proof-of-play. The key public endpoint is GET /v1/advertiser/proof/.well-known/public-key which exposes the verifier the public keys for every active screen. Buyers can independently verify any PoP entry against that key set.

Why this matters: programmatic DOOH spend has historically been audited against billing logs supplied by the SSP — i.e. by the same party that gets paid for the playout. PoP breaks that conflict by making the screen itself the attestor and the signature an unforgeable proof. A buyer doesn't have to trust the SSP's billing; they have a cryptographic receipt of every playout they paid for.

The OAAA has been pushing PoP as an industry standard since 2024; adoption is still concentrated in newer networks. Trillboards bakes PoP into every playout by default — there is no opt-out — and the entry lands in our completed impressions ledger.