Rational Protocols and Attacks in Blockchain System

Algorithm 3

The Backbone protocol.

	Step 1. Each party i maintains a local chain C and updates it by invoking PoW algorithm (refer to Algorithm 1).
	Step 2. However, party does not update it immediately when C has any change. Instead, first checks if there are any other “better” chain by verifying its communication tape.
	Step 3. An input x is determined by some functions therein and local chain C is updated to be by invoking PoW.
	Step 4. The updated chain is broadcasted to other parties. Note that Backbone consensus protocol is depended on input contribution function and the chain reading function . Readers may find more details in [51].