Generating and Using Ephemeral Identifiers and Message Integrity Codes

A computer-implemented method for generating ephemeral identifiers, the method comprising:

• determining, by one or more computing devices, a current time-count;
• determining, by the one or more computing devices, a time-modified identifier based at least in part on a static identifier and the current time-count;
• and
• determining, by the one or more computing devices, an ephemeral identifier based at least in part on the time-modified identifier and a rotation key.

A system for using ephemeral identifiers, the system comprising:

• a plurality of beacon devices, wherein a plurality of static identifiers are respectively associated with the plurality of beacon devices, and wherein each of the plurality of beacon devices is configured to periodically determine an ephemeral identifier based on its respective static identifier and a current time-count;
• an observing entity configured to receive a first ephemeral identifier from a first beacon device of the plurality of beacon devices;
• and
• a verifying entity configured to:
• receive the first ephemeral identifier from the observing entity;
• and
• determine an identity of the first beacon device by locating the first ephemeral identifier in a pre-computed ephemeral identifier cache;
• wherein the first ephemeral identifier comprises a time-varied obscuration of the static identifier associated with the first beacon device, the first ephemeral identifier having been generated using an obscuring function known only to the first beacon device and the verifying entity, such that the observing entity cannot compute the identity of the first beacon device independent from communication with the verifying entity.

A beacon device, comprising:

• one or more processors;
• and
• a memory storing instructions that, when implemented by the one or more processors, cause the one or more processors to perform operations, the operations comprising:
• determining a current time-count;
• determining a time-modified identifier based at least in part on a static identifier and the current time-count;
• determining an ephemeral identifier based at least in part on the time-modified identifier and a rotation key;
• and
• emitting a message containing the ephemeral identifier.