Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing view change. One of the methods is to be implemented on a blockchain maintained by a number (N) of nodes and performed by a first node of the N nodes that is in a view change protocol. The method includes: obtaining, respectively from at least Q second nodes of the N nodes, at least Q first messages each comprising (1) a consistent current view known to the second node indicating a primary node designated among the N nodes and (2) a consistent current sequence number known to the second node, the current sequence number associated with a latest transaction or a latest block, wherein the current sequence number is larger than a first sequence number known to the first node; and responsive to obtaining the at least Q first messages, ending the view change protocol.

Abstract: This disclosure relates to blockchain-based transaction processing. In one aspect, a method includes obtaining pieces of transaction data. At least a portion of the pieces of transaction data have a respective group identifier that identifies a node group for the piece of transaction data. Each node group includes multiple blockchain nodes. Pieces of transaction data that have a same first group identifier that identifies a first node group are identified in the obtained pieces of transaction data. The pieces of transaction data are packaged into a first packaging result based on the pieces of transaction data having the same first group identifier. The first packaging result is submitted to a blockchain for storage.

Abstract: Consensus methods, systems, and apparatus, including computer programs encoded on computer storage media, are provided. One of the methods is to be implemented on a blockchain maintained by a number (N) of nodes. One of the nodes acts as a primary node and the other (N?1) nodes act as backup nodes. The method includes: detecting a change in a current height H of the blockchain; determining the primary node based on a parameter P and the number of nodes N, wherein the parameter P is proportional to the current height H of the blockchain; in response to determining that the one of the N nodes is the primary node, executing a PBFT normal operation protocol as the primary node; and in response to determining that the one of the N nodes is not the primary node, executing the PBFT normal operation protocol as one of the backup nodes.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing view change. One of the methods is to be implemented on a blockchain maintained by a number (N) of nodes and performed by a first node of the N nodes that is in a view change protocol. The method includes: obtaining, respectively from at least Q second nodes of the N nodes, at least Q first messages each comprising (1) a consistent current view known to the second node indicating a primary node designated among the N nodes and (2) a consistent current sequence number known to the second node, the current sequence number associated with a latest transaction or a latest block, wherein the current sequence number is larger than a first sequence number known to the first node; and responsive to obtaining the at least Q first messages, ending the view change protocol.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for consensus system downtime recovery. One of the methods includes: obtaining a pre-prepare message from the primary node; multicasting a prepare message indicating an acceptance of the pre-prepare message to at least some of the primary node and the other (N?2) backup nodes; obtaining (Q?1) or more prepare messages respectively from (Q?1) or more of the backup nodes; storing the pre-prepare message and the (Q?1) or more prepare messages; multicasting a commit message to at least some of the primary node and the other backup nodes, the commit message indicating that the one backup node agrees to the (Q?1) or more prepare messages; and obtaining, respectively from Q or more nodes among the primary node and the backup nodes, Q or more commit messages each indicating that the corresponding node agrees to (Q?1) or more prepare messages.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing view change. One of the methods is to be implemented on a blockchain and performed by a first node of N nodes in a view change protocol. The method includes: multicasting a view change message to at least some of the N nodes; obtaining, respectively from at least Q second nodes of the N nodes, at least Q echo messages each comprising: a consistent current view known to the second node indicating a primary node designated among the N nodes, and a consistent current sequence number known to the second node, the current sequence number associated with a latest transaction or a latest block, the current sequence number is larger than a first sequence number known to the first node; and responsive to obtaining the at least Q echo messages, ending the view change protocol.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing view change. One of the methods is to be implemented on a blockchain maintained by a number (N) of nodes and performed by a first node of the N nodes that is in a view change protocol. The method includes: obtaining, respectively from at least Q second nodes of the N nodes, at least Q first messages each comprising (1) a consistent current view known to the second node indicating a primary node designated among the N nodes and (2) a consistent current sequence number known to the second node, the current sequence number associated with a latest transaction or a latest block, wherein the current sequence number is larger than a first sequence number known to the first node; and responsive to obtaining the at least Q first messages, ending the view change protocol.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for consensus system downtime recovery. One of the methods includes: obtaining a pre-prepare message from the primary node; multicasting a prepare message indicating an acceptance of the pre-prepare message to at least some of the primary node and the other (N?2) backup nodes; obtaining (Q?1) or more prepare messages respectively from (Q?1) or more of the backup nodes; storing the pre-prepare message and the (Q?1) or more prepare messages; multicasting a commit message to at least some of the primary node and the other backup nodes, the commit message indicating that the one backup node agrees to the (Q?1) or more prepare messages; and obtaining, respectively from Q or more nodes among the primary node and the backup nodes, Q or more commit messages each indicating that the corresponding node agrees to (Q?1) or more prepare messages.

Abstract: Consensus methods, systems, and apparatus, including computer programs encoded on computer storage media, are provided. One of the methods is to be implemented on a blockchain maintained by a number (N) of nodes. One of the nodes acts as a primary node and the other (N?1) nodes act as backup nodes. The method includes: detecting a change in a current height H of the blockchain; determining the primary node based on a parameter P and the number of nodes N, wherein the parameter P is proportional to the current height H of the blockchain; in response to determining that the one of the N nodes is the primary node, executing a PBFT normal operation protocol as the primary node; and in response to determining that the one of the N nodes is not the primary node, executing the PBFT normal operation protocol as one of the backup nodes.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for consensus system downtime recovery. One of the methods includes: multicasting a pre-prepare message to at least some of the backup nodes; obtaining (Q-1) or more prepare messages respectively from (Q-1) or more of the backup nodes, wherein the prepare messages each indicate an acceptance of the pre-prepare message by the corresponding backup node; storing the pre-prepare message and the (Q-1) or more prepare messages; multicasting a commit message to at least some of the backup nodes, the commit message indicating that the primary node agrees to the (Q-1) or more prepare messages; and obtaining, respectively from Q or more nodes among the primary node and the backup nodes, Q or more commit messages each indicating that the corresponding node agrees to (Q-1) or more prepare messages received by the corresponding node.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for implementing blockchain-based private transactions are provided. One of the methods is performed by a first blockchain node to a private transaction, the method including: determining one or more second blockchain nodes to the private transaction according to a blockchain contract in a public blockchain; transmitting transaction information to the one or more second blockchain nodes, the transaction information comprising one or more senders of the private transaction, one or more recipients of the private transaction, and one or more transaction amounts of the private transaction; obtaining a signature from each of a number of the one or more second blockchain nodes certifying receipt of the transaction information; and in response to obtaining the number of the signatures over a threshold, storing at least a representation of the private transaction and the signatures in the public blockchain.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing view change. One of the methods is to be implemented on a blockchain and performed by a first node of N nodes in a view change protocol. The method includes: multicasting a view change message to at least some of the N nodes; obtaining, respectively from at least Q second nodes of the N nodes, at least Q echo messages each comprising: a consistent current view known to the second node indicating a primary node designated among the N nodes, and a consistent current sequence number known to the second node, the current sequence number associated with a latest transaction or a latest block, the current sequence number is larger than a first sequence number known to the first node; and responsive to obtaining the at least Q echo messages, ending the view change protocol.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing view change. One of the methods is to be implemented on a blockchain maintained a number (N) of nodes and performed by a first node of the N nodes that is in a view change protocol. The method includes: obtaining, respectively from at least Q second nodes of the N nodes, at least Q first messages each comprising (1) a consistent current view known to the second node indicating a primary node designated among the N nodes and (2) a consistent current sequence number known to the second node, the current sequence number associated with a latest transaction or a latest block, wherein the current sequence number is larger than a first sequence number known to the first node; and responsive to obtaining the at least Q first messages, ending the view change protocol.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for consensus system downtime recovery. One of the methods includes: obtaining a pre-prepare message from the primary node; multicasting a prepare message indicating an acceptance of the pre-prepare message to at least some of the primary node and the other (N?2) backup nodes; obtaining (Q?1) or more prepare messages respectively from (Q?1) or more of the backup nodes; storing the pre-prepare message and the (Q?1) or more prepare messages; multicasting a commit message to at least some of the primary node and the other backup nodes, the commit message indicating that the one backup node agrees to the (Q?1) or more prepare messages; and obtaining, respectively from Q or more nodes among the primary node and the backup nodes, Q or more commit messages each indicating that the corresponding node agrees to (Q?1) or more prepare messages.

Abstract: Implementations of the present disclosure include setting, by a first consensus node, a timer that runs out before a timeout of a view change; sending, to a second consensus node, a request for one or more consensus messages missing by the first consensus node in response to the timer running out; receiving, from the second consensus node, the one or more consensus messages each digitally signed by a private key of a corresponding consensus node that generates the respective one or more consensus messages; and determining that a block of transactions is valid, if a quantity of commit messages included in the received one or more consensus messages is greater than or equal to 2f+1, where f is a maximum number of faulty nodes that is tolerable by the blockchain based on practical Byzantine fault tolerance.