# Emma Holmen: A Study of Cryptographic Hash Functions

**Time: **
Mon 2021-08-23 11.00 - 12.00

**Location: **
Zoom, meeting ID: 695 2070 6048 (password required, contact arias@math.su.se)

**Respondent: **
Emma Holmen

**Abstract:** This paper discusses the concept of cryptographic hash functions, functions that are widely used in industry. The aim is to understand how cryptographic hash functions can be constructed, compare different types of hash functions and show some applications. We look in depth at two constructions of hash functions; SHA-256 of Merkle Damgård construction and Cayley hashes. We also dive into two applications for cryptographic hash functions; digital signatures and pseudorandom generation. While Cayley hashes are built on an underlying mathematical problem with documented hardness, it is slower to compute than SHA-256 and other hash functions where the security is simply presumed. Since speed is an important factor for practical use, the industry standard of hash functions today does not rely on an underlying mathematical problem. Solving the problem of finding a fast cryptographic hash function with proven mathematical hardness is therefore still open.