A blockchain, originally block chain, is a growing list of records, called blocks, which are linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data (generally represented as a merkle tree root hash).

In the present book, fifteen typical literatures about blockchain technology published on international authoritative journals were selected to introduce the worldwide newest progress, which contains reviews or original researches on information security, secure communication, cryptography, cryptographic hash function, block time, etc. We hope this book can demonstrate advances in blockchain technology as well as give references to the researchers, students and other related people.