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.