Methods, systems, and apparatus, including a method for updating user consent in a verifiable manner. In some aspects, a method includes receiving, from a client device, a request including an attestation token. The attestation token includes a set of data that includes at least a user identifier that uniquely identifies a user of the client device, a token creation time that indicates a time at which the attestation token was created, user consent data specifying whether one or more entities that receive the attestation token are eligible to use data of the user, an action to be performed in response to the request. The attestation token also includes a digital signature of at least a portion of the set of data, including at least the user identifier and the token creation time. An integrity of the request is verified using the attestation token.