Abstract: A method can include, by operation of a user device, receiving beacon data via a wireless signal. Beacon data can include unencrypted data that includes a key identification (ID) corresponding to a private key/public key pair, a time value, and a location value. Beacon data can also include encrypted data that includes at least a beacon ID, a beacon time value, and a beacon location value. If the unencrypted time value is within a predetermined range of a current time value of the user device, the beacon data can be stored in a user record with a user ID. Periodically, the user record can be uploaded to a tracking system. Corresponding devices and systems are also disclosed.