Abstract: The disclosure provides an approach for formally verifying a state machine replication protocol (SMRP) based on a model SMRP, and deploying a distributed system, such as a blockchain, that runs using the formally verified SMRP. The approach provides a verifier that models the SMRP within a model distributed system. Modeling includes modeling actions by model components of the model distributed system so as to transition state of the model SMRP, and then verifying that applicable invariants hold true after the state transition. As long as the model and actual SMRPs are logically equivalent, then launching an actual SMRP based on the model SMRP should preserve formally verified byzantine fault tolerance within the actual SMRP of the distributed system.

Abstract: Disclosed are examples of systems and methods for determining a blockchain time. One such method comprises receiving, by a non-primary replica node, a pre-prepare message having a timestamp representing a local time of a primary replica node in a blockchain network, verifying, by the non-primary replica node, that a difference between the local time of the primary replica node and a local time of the non-primary replica node does not exceed a hard time limit established for the blockchain network; responding, to the primary replica node, that a time value of the timestamp is within acceptable bounds of the local time of the non-primary replica node; and after consensus is reached amongst the non-replica nodes regarding acceptance of the time value, saving a current blockchain time for the blockchain network based on the timestamp.

Abstract: In some embodiments, a method implements a Byzantine fault tolerant protocol. A first replica detects a condition to cause a view change procedure to move from a current view to a next view. The first replica sends a message indicating the first replica wants to leave the current view. Also, the first replica receives a set of messages from second replicas indicating a respective second replica wants to leave the current view. The first replica determines when a property is received to the leave the current view based on the set of messages from the set of second replicas. When it is determined the property is received, the first replica performs a process to leave the current view. When it is determined the property is not received, the first replica stays in the current view and participating in processing a request from a client in the current view.

Abstract: In some embodiments, a method implements a Byzantine fault tolerant protocol. A first replica detects a condition to cause a view change procedure to move from a current view to a next view. The first replica sends a message indicating the first replica wants to leave the current view. Also, the first replica receives a set of messages from second replicas indicating a respective second replica wants to leave the current view. The first replica determines when a property is received to the leave the current view based on the set of messages from the set of second replicas. When it is determined the property is received, the first replica performs a process to leave the current view. When it is determined the property is not received, the first replica stays in the current view and participating in processing a request from a client in the current view.