Κατεύθυνση Ηλεκτρονικός Αυτοματισμός (Η/Α, με πρόσθετη εξειδίκευση στην Πληροφορική και στα πληροφοριακά συστήματα)
Library of the School of Science

2018-07-11

2018

Pavlozas Antonios-Dionysios

Διονύσης Ι.Ρεΐσης, Αναπληρωτής Καθηγητής, Τμήματος Φυσικής, Εθνικό Καποδιστριακό Πανεπιστήμιο Αθηνών
Εμμανουήλ Χ. Τσίλης, Επίκουρος Καθηγητής , Τμήματος Φυσικής, Εθνικό Καποδιστριακό Πανεπιστήμιο Αθηνών
Γιώργης Αλεξάκης, Επίκουρος Καθηγητής , Τμήματος Φυσικής, Εθνικό Καποδιστριακό Πανεπιστήμιο Αθηνών

Κρυπτογράφηση με τον αλγόριθμο AES 128

Greek

Encryption with the AES 128 algorithm

For many centuries Cryptography was seen as a rather occult art, accessible to a few and initiates. Until the middle of the 20th century its use was limited to military and governmental applications, and related implementations and technologies were subject to severe restrictions. Today, Modern Cryptography provides applications in every field of our everyday life and that is why it is of particular importance. For this reason, any information transmitted should be converted into an unrecognizable form to ensure its security. This data processing (encryption) needs to happen in real time, and for this purpose several cryptographic algorithms have been developed where, although their work is the same, they handle and transform the data in a different way.
In the present thesis the AES (Advanced Encryption Standard) algorithm is presented, which is also known as Rijndael. Is a symmetric block cipher and is based on substitution - permutation networks, while it can be efficiently implemented both in software and hardware. The AES algorithm provides encryption capability with three keys of different size: key of 128 bits with 10 rounds, key of 192 bits with 12 rounds and key of 256 bits with 14 rounds presenting a high resistance to cryptanalytic attacks every time. This work focuses on AES with a 128-bit input key.
More specifically, in the first chapter of the thesis an introduction to Cryptography is presented, presenting its basic concepts, security rating models and the most known cryptographic attacks. In second chapter, the classical algorithms are first presented, and then reference is made to modern cryptosystems. Then a comparison is made between the symmetric and asymmetric algorithms. Third chapter is the main body of work as the AES algorithm is illustrated and explained. The necessary mathematical background is given and the transformations of the algorithm are analyzed. We present how algorithm keys are expanded, as well as encryption and decryption procedures. Finally, it refers to security issues and the resistance of AES to cryptanalytic attacks. The fourth chapter presents the algorithm implementation method using the descriptive VHDL language and the Quartus II design tool. Finally, fifth chapter 5 draws conclusions and makes suggestions for future work.

Technology - Computer science

encryption, decryption, key, VHDL, AES

Yes

3

Yes

44

102

File access is restricted only to the intranet of UoA.

https://pergamos.lib.uoa.gr/uoa/dl/object/2778198