This work presents recent developments in hashing algorithm design. Hashing is the process of creating a short digest (i.e., 64 bits) for a message of arbitrary length, for example 20 Mbytes. Hashing algorithms were first used for searching records in databases; they are central for digital signature applications and are used for authentication without secrecy. Covering all practical and theoretical issues related to the design of secure hashing algorithms the book is self contained; it includes an extensive bibliography on the topic.