This is a comprehensive description of the cryptographic hash function BLAKE, one of the five final contenders in the NIST SHA3 competition, and of BLAKE2, an improved version popular among developers. It describes how BLAKE was designed and why BLAKE2 was developed, and it offers guidelines on implementing and using BLAKE, with a focus on software implementation.In the first two chapters, the authors offer a short introduction to cryptographic hashing, the SHA3 competition and BLAKE. They review applications of cryptographic hashing, they describe some basic notions such as security definitions and state-of-the-art collision search methods and they present SHA1, SHA2 and the SHA3 finalists. In the chapters that follow, the authors give a complete de...