Communication of sensitive data in restricted data channel

Abstract

Communication of information relating to an event is described, where the information is contained in a data field. Methods of communicating and obtaining the information are described, together with suitable apparatus for performing these methods. One or more elements of information relating to the event are obtained and used to determine a cryptographic record of the event. A first set of places in the data field are filled by a combination of some or all of each of the elements together with time information associated with the event. The cryptographic record is used to fill a second set of places in the data record. On reception of a message including the data field, the data field can be resolved into the first set of places and the second set of places. The time information associated with the event can then be determined and used to establish the whole or partial elements of information that were combined with the time information to fill the first set of places. Whole elements of information are then established from any partial elements. When these elements are all established, they can be used to calculate cryptographic record data which can be matched against the cryptographic record from the second set of places in the data field to determine that the elements of information are correct.