National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Proving security of hash functions
Zpěváček, Marek ; Příhoda, Pavel (advisor) ; Žemlička, Jan (referee)
This thesis focuses on proof of reduction from approximate SBP to SIS. The proof was already accomplished by Mikl'os Ajtai in 1996 in his groun- dbreaking work, however his proof lacks level of detail. The reduction is worst-case to average-case and no reduction of this type was known prior to the Ajtai's one. That is the reason why we found appropriate to return to the proof and provide it in more detailed form. Furthermore, the complexity of basic lattice problems is summarized. Based on these complexities and proven reduction, it is possible to define collision-resistant hash functions. This work is also briefly focused on such functions. 1
Audiovisual cryptography
Zpěváček, Marek ; Tůma, Jiří (advisor) ; Boháček, Milan (referee)
This work examines the visual cryptography, which was introduced in 1995 by Moni Naor and Adi Shamir. It is a cryptosystem which allows us to share a secret among many users and reconstruction of secret can be done by human visual system only. Firstly, the relevant notations are defined and related theorems are proved. Additionally, some basic schemes and a general (k, k)-scheme are described. Main part of this work consists of an algorithm for creating general (k, n)-scheme. For every scheme, we prove its security and reconstruction correctness. Finally, we briefly mention a few possible extensions. Powered by TCPDF (www.tcpdf.org)

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