Orhun Kara

dblp:24/1044 · DBLP profile ↗
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9ranked-venue papers
4as first author
4since 2021 · last 2024
0000-0002-9685-6625ORCID · corroborated

Domains — the database's venue-derived domains; a paper can count in several

Security and privacy · 7 · 2 first-author · 4 since 2021Systems, architecture and hardware · 1 · 1 first-authorDatabases, data management, data science and information retrieval · 1 · 1 first-authorTheory of computation · 1 · 1 first-author
YearPublicationVenuePosition
2024 Correction to "A New Construction Method for Keystream Generators"
abstract
The authors would like to extend their apologies for the inadvertent inclusion of an erroneous index of the matrix${M}$for DIZY-80 in[1]. We sincerely regret any inconvenience caused by this typographical error and appreciate the chance to rectify it.
Çagdas Gül, Orhun Kara
IEEE Trans. Inf. Forensics Secur.2
2023 A New Construction Method for Keystream Generators
abstract
We introduce a new construction method of diffusion layers for Substitution Permutation Network (SPN) structures along with its security proofs. The new method can be used in block ciphers, stream ciphers, hash functions, and sponge constructions. Moreover, we define a new stream cipher mode of operation through a fixed pseudorandom permutation and provide its security proofs in the indistinguishability model. We refer to a stream cipher as a Small Internal State Stream (SISS) cipher if its internal state size is less than twice its key size. There are not many studies about how to design and analyze SISS ciphers due to the criterion on the internal state sizes, resulting from the classical tradeoff attacks. We utilize our new mode and diffusion layer construction to design an SISS cipher having two versions, which we call DIZY. We further provide security analyses and hardware implementations of DIZY. In terms of area cost, power, and energy consumption, the hardware performance is among the best when compared to some prominent stream ciphers, especially for frame-based encryptions that need frequent initialization. Unlike recent SISS ciphers such as Sprout, Plantlet, LILLE, and Fruit; DIZY does not have a keyed update function, enabling efficient key changing.
Çagdas Gül, Orhun Kara
IEEE Trans. Inf. Forensics Secur.2
2022 Integral characteristics by keyspace partitioning
Fatih Demirbas, Orhun Kara
Des. Codes Cryptogr.2
2022 Plaintext recovery and tag guessing attacks on authenticated encryption algorithm COLM
Sirri Erdem Ulusoy, Orhun Kara, Mehmet Önder Efe
J. Inf. Secur. Appl.2
2019 On Analysis of Lightweight Stream Ciphers with Keyed Update
abstract
As the need for lightweight cryptography has grown even more due to the evolution of the Internet of Things, it has become a greater challenge for cryptographers to design ultra lightweight stream ciphers in compliance with the rule of thumb that the internal state size should be at least twice as the key size to defend against generic Time-Memory-Data Tradeoff (TMDT) attacks. However, Recently in 2015, Armknecht and Mikhalev sparked a new light on designing keystream generators (KSGs), which in turn yields stream ciphers, with small internal states, called KSG with Keyed Update Function (KSG with KUF), and gave a concrete construction named Sprout. But, currently, security analysis of KSGs with KUF in a general setting is almost non-existent. Our contribution in this paper is two-fold. 1) We give a general mathematical setting for KSGs with KUF, and for the first time, analyze a class of such KSGs, called KSGs with Boolean Keyed Feedback Function (KSG with Boolean KFF), generically. In particular, we develop two generic attack algorithms applicable to any KSG with Boolean KFF having almost arbitrary output and feedback functions where the only requirement is that the secret key incorporation is biased. We introduce an upper bound for the time complexity of the first algorithm. Our extensive experiments validate our algorithms and assumptions made thereof. 2) We study Sprout to show the effectiveness of our algorithms in a practical instance. A straightforward application of our generic algorithm yields one of the most successful attacks on Sprout.
Orhun Kara, Muhammed F. Esgin
IEEE Trans. Computers1
2015 Practical Cryptanalysis of Full Sprout with TMD Tradeoff Attacks
Muhammed F. Esgin, Orhun Kara
SAC2
2013 Square reflection cryptanalysis of 5-round Feistel networks with permutations
Orhun Kara
Inf. Process. Lett.1
2012 Fixed Points of Special Type and Cryptanalysis of Full GOST
Orhun Kara, Ferhat Karakoç
CANS1
2007 A New Class of Weak Keys for Blowfish
Orhun Kara, Cevat Manap
FSE1