International Association
for Cryptologic Research

Name: Özgül Küçük
Topic: Design and Analysis of Cryptographic Hash Functions
Category: secret-key cryptography

Description: The topic of this thesis is the design and analysis of cryptographic hash functions. \r\n\r\nA hash function is a map from variable-length input bit strings to fixed-length output bit strings. Despite their simple \r\ndefinition, hash functions play an essential role in a wide area \r\nof applications such as digital signature algorithms, message \r\nauthentication codes, password verification, and key derivation. \r\n\r\n\r\nThe main contribution of this thesis is a novel and elegant proposal \r\nof a cryptographic hash function. \r\nIn this thesis, we approach the problem of the design and analysis of \r\ncryptographic hash functions with a particular example, the hash function Hamsi.\r\nThe design of Hamsi is based on the use of a relatively light underlying\r\nprimitive in each iteration of the mode of operation, combined with \r\na strong message expansion function.\r\nWe investigate the design constraints of this approach by analyzing Hamsi.\r\nIn the first part, we cover the design aspects of Hamsi \r\nand also propose a variant called Hamsi$^\\oplus$. \r\nIn the sequent parts we provide analysis results, namely\r\nindifferentiability analysis and collision analysis. \r\nFinally, as a separate research study we analyze the initialization \r\nof the stream cipher Grain.[...]