Cryptanalysis of Hash functions Using Graphics Processing Units

Abstract

This thesis consists of six chapters, an appendix, and a bibliography. Chapter 1: A brief introduction to how many programs are secured through an authentication system based on username and password combinations. First, a password is generated by the user and stored in a secure file or in the database system to secure access to the system. To ensure that these passwords are always secure, even if we are not sure of a site's security, it is common practice to use a cryptographic hash function to generate a password output summary and store it with user credentials. If the user reconnects, the cipher hash function computes the password summary in plain text and compares its stream to the previously stored field. Due to the characteristics of the cryptographic hash, the password summary cannot be easily reversed. Therefore, the possibility that the opponent has partial information that would allow him to predict the password is not possible. However, password authentication schemes are often built from the limitations of human memory, and users tend to choose passwords that are easy to remember and do not have enough randomness to produce predictable passwords. Chapter 2: This chapter deals with the precise design of hash functions because password hash systems mainly rely on the cryptographic features of hash functions, whereby a hash function can be defined as any mathematical function that can be used to map arbitrary size data to fixed small size data. The values obtained by the hash function are defined as "feeds" or as hash symbols, hash values, or just hashes. Therefore, the job output can be considered the "digital footprint" portion of the original document. Also, this chapter includes the description of the hash function SHA-3.