In a first aspect, the present invention provides a protocol for
communications across a securable communication channel between a first
device and a second device. The protocol includes the transmission of a
plurality of uniquely identifiable messages which each include
security-related data, from the first device to the second device. The
protocol includes determining whether a subset of messages that are
received by the second device comply with at least one predetermined
message criterion and are identifiable as having been sent from the first
device. In the event that said subset of messages are determined to
comply with the predetermined verification criterion (or criteria) and
are identifiable as having been sent from the first device, the
security-related data is determined to have been successfully
communicated to the second device.