Abstract: A method includes identifying a set of computing-resistant puzzles and receiving human-input proposed solutions to at least a subset of the puzzles. The method further includes confirming the validity of the human-input proposed solutions and producing a proof-of-work based on at least a threshold quantity of validated human-input proposed solutions. A new block including the produced proof-of-work is added to a blockchain database.

Abstract: A method includes obtaining a plurality of proof-of-stake blocks that include user data to be added to a blockchain database, and each of the proof-of-stake blocks is confirmed. In response to confirming each of the proof-of-stake blocks, each of the proof-of-stake blocks is added to the blockchain database. The method further includes obtaining a proof-of-work block that includes a representation of each of the proof-of-stake blocks added to the blockchain database and confirming the proof-of-work block. In response to confirming the proof-of-work block, the method adds the proof-of-work block to the blockchain database.

Abstract: A method includes distributing a plurality of key pieces associated with an encryption key to a plurality of key piece holders, adding release data to a blockchain database including sensitive data encrypted with the encryption key and a specified release date. The method further includes providing instructions to key piece holders to add respective key pieces to the blockchain database at the specified release date to facilitate time-based release of the sensitive data.