Deletion of blocks in a blockchain

A computer program product for deleting a block from a blockchain, the blockchain maintained by a plurality of participant nodes in a network, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by one or more processors to cause the one or more processors to:

• calculate, by a participant node of the plurality of participant nodes, a proof of work for a new block to be added to the blockchain;
• create, by the participant node, the new block comprising a block header;
• determine, by the participant node, whether a timestamp in an oldest block in the blockchain is older than a current time plus a pre-configured retention period, and whether a current number of blocks in the blockchain is greater than or equal to a pre-configured minimum number of blocks to be maintained in the blockchain;
• when the timestamp in the oldest block in the blockchain is older than the current time plus the pre-configured retention period, and when the current number of blocks in the blockchain is greater than or equal to the pre-configured minimum number of blocks to be maintained in the blockchain, delete, by the participant node, the oldest block in the blockchain;
• add, by the participant node, a hash of an oldest remaining block and an original number of blocks of the blockchain to the block header of the new block;
• and
• broadcast, by the participant node, a message announcing the new block to remaining participant nodes of the plurality of participant nodes.

A system comprising:

• a participant node of a plurality of participant nodes in a network, the plurality of participant nodes maintaining a blockchain, the participant node for:
• calculating a proof of work for a new block to be added to the blockchain;
• creating the new block comprising a block header;
• determining whether a timestamp in an oldest block in the blockchain is older than a current time plus a pre-configured retention period, and whether a current number of blocks in the blockchain is greater than or equal to a pre-configured minimum number of blocks to be maintained in the blockchain;
• when the timestamp in the oldest block in the blockchain is older than the current time plus the pre-configured retention period, and when the current number of blocks in the blockchain is greater than or equal to the pre-configured minimum number of blocks to be maintained in the blockchain, deleting the oldest block in the blockchain;
• adding a hash of an oldest remaining block and an original number of blocks of the blockchain to the block header of the new block;
• and
• broadcasting a message announcing the new block to remaining participant nodes of the plurality of participant nodes.