Abstract: This disclosure relates to data security and cryptography. In one aspect, a method includes updating a user interface of a client device to present user interface controls that enable a user to specify data privacy settings that define how entities collect, store, and use data of the user. The data security system receives a request to modify a data privacy setting for one or more entities from the client device based on user interaction with one or more of the user interface controls. The request includes an ephemeral user identifier for the user and an attestation token. The data security system validates the request using at least the ephemeral user identifier and the attestation token. The data security system transmits data instructing the entity to modify usage of the user data based on the modified given data privacy setting to each of the one or more entities.

Abstract: This disclosure relates to data security and cryptography. In one aspect, a method includes receiving a request for a subscription token for a given user by a data security system from a publisher computing system of a publisher. The request includes user identification information provided to the publisher by the given user when subscribing to electronic content of the publisher. The data security system generates the subscription token which includes a set of data that includes a first encrypted user identifier generated by encrypting a first user identifier for the given user using an encryption key of the data security system, and, for each of one or more content platforms, an attachment element that includes a second encrypted user identifier generated by encrypting a second user identifier for the given user using an encryption key of the content platform and transmitting the subscription token to the publisher computing system.