Practical Time-Release Blockchain

Abstract

Time-release cryptography is a special encryption technique that allows a message to be hidden for some time. The previous schemes have shortcomings in that the encryptor should predict the decryptor’s computing power precisely or the trusted agent should be always available. In this paper, we propose a new, practical time-release blockchain, and find the key to decrypt the content after a certain time. In order to verify the effectiveness of the blockchain system automatically, which uses the proof-of-work (PoW) and the consensus algorithm in the the proposed technique, we have implemented a prototype version of our blockchain system using Python. The proposed method has the following advantages. First, the decryption time is automatically adjusted, even if the miner’s computing power changes over time. Second, unlike previous time-lock puzzle schemes, our algorithm does not require additional computation work for solving the puzzle. Third, our scheme does not need any trusted agents (third parties). Fourth, the proposed method uses standard cryptographic algorithms.

Stateful Layered Chain Model to Improve the Scalability of Bitcoin

“…Block header contains information about the block such as its version, its hash, previous block hash, Merkle root, timestamp, di culty, and Nonce as illustrated in table 1. On the other hand, transactions are recorded in the block body [10]. Figure 2 shows Bitcoin blockchain structure.…”

Multiple Time Servers Timed-Release Encryption Based on Shamir Secret Sharing

“…In 1996, Rivest et al 4 first proposed two preliminary TRE construction schemes, the first is TLP scheme based on factorization problem, and the second is the sender issues time and message to the agent, which laid the theoretical foundation for the sustainable research of TRE. So far, the construction of TRE scheme includes TLP [5][6][7][8][9][10] , agents [11][12][13][14][15][16][17] and other methods [18][19][20][21][22][23] . In the TRE scheme constructed based on TLP, the decryption key is hidden in a mathematical formula.…”

“…In the TRE scheme constructed based on other methods (network method, physical method), for example, Wang et al 19 studied a scheme based on indistinguishability obfuscation and TRE, encapsulating the sender's encryption and receiver's decryption by a circuit, that is, proposed a TRE scheme using a obfuscator to obfuscate circuits, but the implementation process is not efficient. Li et al 20 proposed a research scheme based on the smart contracts in Ethereum blockchain network to realize the scheduled release of data, recruiting several network nodes as middlemen (each middleman needs to pay a deposit) to send the decryption key to the receiver at the specified decryption time Chae et al 21 proposed a time-release blockchain scheme combining PoW algorithm and TLP algorithm of blockchain. Compared with the scheme proposed by Liu et al 22 and Malavolta et al 23 , it has a series of advantages such as using standard cryptographic algorithms and not requiring additional computation work.…”