Protocol Behaviours. Safety Properties We assume that the provider and customer communicate by sending messages asynchronously using a non-Byzantine model11. Messages can take arbitrarily long to be delivered and may be duplicated and/or lost but not corrupted. We also define what are called safety properties for the protocol [10]. The safety properties for this protocol are that: – Only an offer that has been sent by the customer can be accepted.
Protocol Behaviours. Safety Properties We assume that the provider and customer communicate by sending messages asynchronously using a non-Byzantine model7. Messages can take arbitrarily long to be delivered and may be duplicated and/or lost but not corrupted. We also define what are called safety properties for the protocol [15]. The safety properties for this protocol are that: – Only an offer that has been sent by the customer can be accepted. – Only one offer can be accepted in an instance of the re-negotiation protocol. – An offer which has been rejected by the provider cannot be accepted later. – The acceptance of an offer by the provider renders all other outstanding of- fers within the instance of the re-negotiation protocol invalid (i.e. they are revoked ). – A RenegotiationNotPossible message sent from the provider to the customer means that all outstanding offers have been revoked. Safety properties are protocol behaviours that cannot be broken. If the safety properties are broken then one of the protocol participants has exhibited a fault of some kind.
