Aspects of the present disclosure relate to an apparatus comprising first interface circuitry to communicate with relying party circuitry, the first interface circuitry being configured to receive, from the relying party circuitry, an attestation request in respect of a processing operation requested by attester circuitry to be performed by the relying party circuitry; second interface circuitry to communicate with the attester circuitry, the second interface circuitry being configured to: transmit the attestation request to the attester circuitry; and receive, from the attester circuitry, evidence data associated with the processing operation, and third interface circuitry to communicate with verifier circuitry, the third interface circuitry being configured to: transmit the evidence data to the verifier circuitry; and receive, from the verifier circuitry, attestation result data indicative of a verification of the evidence data, wherein the first interface circuitry is configured to transmit the attestation result data to the relying party circuitry.