Byzantine fault tolerance protocol for backing up blockchains

A non-transitory computer-readable storage medium containing instructions for using a backup client to back up a blockchain in a state machine replication system comprising N replicas, wherein the instructions, when executed, control a computer system to be operable for:

• sending a plurality of first messages that request first information, the first information including identification information for a set of blocks of the blockchain to the N replicas, wherein each replica in the N replicas maintains a respective instance of the blockchain;
• receiving a plurality of second messages from at least a portion of the N replicas, the plurality of second messages including the first information for the set of blocks from each respective instance of the blockchain that is maintained by the at least the portion of the N replicas;
• analyzing the first information from the plurality of second messages to determine whether a consensus on the first information included in the plurality of second messages is reached by a number of replicas;
• when consensus is reached, sending to a replica a request that identifies, using the identification information, one or more blocks to back up to a backup blockchain;
• receiving second information, that is stored, for the one or more blocks in the respective instance of the blockchain from the replica;
• and
• using the second information to back up the one or more blocks in the backup blockchain.

An apparatus for using a backup client to back up a blockchain in a state machine replication system comprising N replicas, the apparatus comprising:

• one or more computer processors;
• and
• a non-transitory computer-readable storage medium comprising instructions, that when executed, control the one or more computer processors to be operable for:
• sending a plurality of first messages that request first information that includes identification information for a set of blocks of the blockchain to the N replicas, wherein each replica in the N replicas maintains a respective instance of the blockchain;
• receiving a plurality of second messages from at least a portion of the N replicas including the first information for the set of blocks from each respective instance of the blockchain that is maintained by the at least the portion of the N replicas;
• analyzing the first information from the plurality of second messages to determine whether a consensus on the first information included in the plurality of second messages is reached by a number of replicas;
• when consensus is reached, sending a request to a replica that identifies one or more blocks using the identification information to back up to a backup blockchain;
• receiving second information that is stored for the one or more blocks in the respective instance of the blockchain from the replica;
• and
• using the second information to back up the one or more blocks in the backup blockchain.