Symmetric block ciphers are among the most widely used cryptographic primitives. In addition to providing privacy via encryption, block ciphers are used as basic components in the construction of hash functions, message authentication codes, pseudorandom number generator, as part of various cryptographic protocols and etc. One of the most popular block ciphers nowadays is AES (Advanced Encryption Standard), which has been used as a standard of encryption in many countries of the world. In spite of popularity of this cipher a huge attack was found on its key-expansion algorithm some years ago. That is why it is important to analyze carefully this component and understand what weak points admit attacks. Since we know that we can improve existing algorithm to protect cipher from attacks or build up a new algorithm taking into account founded weaknesses so there will be no chance to break it with existing knowledge. The goal of this project is to create some method which can estimate security of encryption algorithm against related-key attacks. For this reason the perspective block cipher is introduced. This cipher is a candidate to the public standard of encryption in Ukraine so that is why this research is very important. Actually the introduced method of estimation is created especially for this cipher but also can be used for other ciphers based on the substitution-permutation network. The developed method was applied to the cipher and results are represented in the report. Also the complexity estimation of this algorithm is expressed. The software implementation is described in the last chapter of report.

Secure wireless communications among sensor nodes is critical to the deployment of wireless sensor networks. However, resource limited sensor nodes cannot afford complex cryptographic algorithms. In this thesis, we propose a low complexity and energy efficient reconfigurable feedback shift register (RFSR) stream cipher, link layer encryption framework RSec and authentication protocol RAuth. RFSR adds one new dimension, reconfigurable cipher structure, to the existing stream ciphers. The proposed RFSR is implemented on a field programmable gate array platform. Simulation results show that much lower power consumption, delay and transmission overhead are achieved compared to the existing microprocessor based cipher implementations. The RSec framework utilizes RFSR ciphers to guarantee message confidentiality. By comparing with other encryption frameworks in terms of energy efficiency, RSec achieves the best benchmark. The RAuth protocol is designed on top of RFSR and RSec. It provides excellent authentication speed and security level by comparing with other authentication protocols. / Graduate / 0544 / 0984 / zggyzz@gmail.com

Secure wireless communications among sensor nodes is critical to the deployment of wireless sensor networks. However, resource limited sensor nodes cannot afford complex cryptographic algorithms. In this thesis, we propose a low complexity and energy efficient reconfigurable feedback shift register (RFSR) stream cipher, link layer encryption framework RSec and authentication protocol RAuth. RFSR adds one new dimension, reconfigurable cipher structure, to the existing stream ciphers. The proposed RFSR is implemented on a field programmable gate array platform. Simulation results show that much lower power consumption, delay and transmission overhead are achieved compared to the existing microprocessor based cipher implementations. The RSec framework utilizes RFSR ciphers to guarantee message confidentiality. By comparing with other encryption frameworks in terms of energy efficiency, RSec achieves the best benchmark. The RAuth protocol is designed on top of RFSR and RSec. It provides excellent authentication speed and security level by comparing with other authentication protocols. / Graduate / 0544 / 0984 / zggyzz@gmail.com

This report describes the works done since May 2010 to December 2012 on breaking Whitenoise encryption algorithm. It is mainly divided into two sections: Studying the stream-cipher developed by Whitenoise lab and its implementation on a FPGA against certain group of indirect attacks called Power Analysis Attacks, and reviewing the process of development and results of experiments applied on a power sampling board which was developed during this project. For the first part the algorithm and the implementation would be reverse engineered and reviewed. Various blocks of the implementation would be studied one by one against some indirect attacks. It would be shown that those attacks are useless or at least very weak against Whitenoise. A new scenario would then be proposed to attack the implementation. An improvement to the new scenario would also be presented to completely hack the implementation. However it would also be shown that the complete hack requires very accurate equipment, large number of computations and applying a lot of tests and thus Whitenoise seems fairly strong against this specific group of attacks. In the next section the requirements of a power consumption measurement setup would be discussed. Then the motivations and goals of building such a board would be mentioned. Some important concepts and consideration in building the board, such as schematic of the amplifier, multilayer designing, embedding a BGA component, star grounding, inductance reduction, and other concepts would be presented. Then the results of applied tests on the produced board would be discussed. The precision of the measurements, some pattern recognition along with some other results would be illustrated. Also some important characteristics such as linearity of measurements would be investigated and proved to exist. In the end some topics as possible future works, such as more pattern recognition, or observing the effect of masks on the power consumption would be suggested. / Graduate

Secure wireless communications among sensor nodes is critical to the deployment of wireless sensor networks. However, resource limited sensor nodes cannot afford complex cryptographic algorithms. In this thesis, we propose a low complexity and energy efficient reconfigurable feedback shift register (RFSR) stream cipher, link layer encryption framework RSec and authentication protocol RAuth. RFSR adds one new dimension, reconfigurable cipher structure, to the existing stream ciphers. The proposed RFSR is implemented on a field programmable gate array platform. Simulation results show that much lower power consumption, delay and transmission overhead are achieved compared to the existing microprocessor based cipher implementations. The RSec framework utilizes RFSR ciphers to guarantee message confidentiality. By comparing with other encryption frameworks in terms of energy efficiency, RSec achieves the best benchmark. The RAuth protocol is designed on top of RFSR and RSec. It provides excellent authentication speed and security level by comparing with other authentication protocols. / Graduate / 0544 / 0984 / zggyzz@gmail.com

In this thesis, one finalist cipher of the Advanced Encryption Standard (AES) block cipher contest, Twofish proposed by Schneier et al, is studied in order to observe the validity of the statement made by Arikan about the randomness of the cipher, which contradicts National Institute of Standards and Technology (NIST)&rsquo / s results. The strength of the cipher to cryptanalytic attacks is investigated by measuring its randomness according to the avalanche criterion. The avalanche criterion results are compared with those of the Statistical Test Suite of the NIST and discrepancies in the second and third rounds are explained theoretically.

Two versions of SNOW, which are word-oriented stream ciphers proposed by P. Ekdahl and T. Johansson in 2000 and 2002, are studied together with cryptanalytic attacks on the first version. The reported attacks on SNOW1.0 are the &ldquo / guess-and-determine attack&rdquo / s by Hawkes and Rose and the &ldquo / distinguishing attack&rdquo / by Coppersmith, Halevi and Jutla in 2002. A review of the distinguishing attack on SNOW1.0 is given using the approach made by the designers of SNOW in 2002 on another cipher, SOBER-t32. However, since the calculation methods for the complexities of the attack are different, the values found with the method of the designers of SNOW are higher than the ones found by Coppersmith, Halevi and Jutla. The correlations in the finite state machine that make the distinguishing attack possible and how these correlations are affected by the operations in the finite state machine are investigated. Since the substitution boxes (S-boxes) play an important role in destroying the correlation and linearity caused by Linear Feedback Shift Register, the s-boxes of the two versions of SNOW are examined for the criteria of Linear Approximation Table (LAT), Difference Distribution Table (DDT) and Auto-correlation Table distributions. The randomness tests are performed using NIST statistical test suite for both of the ciphers. The results of the tests are presented.

Thesis (doctoral)--Universistät Basel, 2007. / Includes bibliographical references (p. 229-247) and index.

Submitted by BEATRIZ FERNANDA LITOLDO null (beatrizfernanda_rc@hotmail.com) on 2016-07-08T18:19:56Z No. of bitstreams: 1 Dissertação de Mestrado.pdf: 2237033 bytes, checksum: b07ab3078616364359ed11c5896ea4b8 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-07-11T18:20:23Z (GMT) No. of bitstreams: 1 litoldo_bf_me_rcla.pdf: 2237033 bytes, checksum: b07ab3078616364359ed11c5896ea4b8 (MD5) / Made available in DSpace on 2016-07-11T18:20:23Z (GMT). No. of bitstreams: 1 litoldo_bf_me_rcla.pdf: 2237033 bytes, checksum: b07ab3078616364359ed11c5896ea4b8 (MD5) Previous issue date: 2016-06-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Esta pesquisa tem por objetivo compreender em que atividades envolvendo problemas de Criptografia podem auxiliar os alunos na exploração das ideias associadas à função afim. As atividades propostas aos estudantes foram estruturadas na forma de enigmas envolvendo contos baseados no personagem Sherlock Holmes, de Sir Arthur Conan Doyle. As atividades foram desenvolvidas com um grupo de alunos do primeiro ano do Ensino Médio da escola pública E. E. Prof. Mycroft, localizada na cidade de Rio Claro/SP. Este trabalho está fundamentado na Metodologia de Pesquisa Intervenção com enfoque Qualitativo. A metodologia de análise dos dados se aproxima de estudos sócio-culturais conjuntamente com estudos cognitivos permeados por meio da resolução de problemas e investigações matemáticas. Como aporte teórico, a dissertação apresenta uma discussão e reflexão acerca do envolvimento da matemática em relação aos campos de poderes (social, politico, econômico, territorial, entre outros) sempre elencando esse entrelaçamento com a constante evolução da criptografia e sua busca constante de cifras seguras e poderosas. Os dados da pesquisa foram produzidos a partir de observações e anotações em um diário de campo, realizadas pela pesquisadora, filmagens e gravações de áudio dos encontros, entrevistas semiestruturadas e fichas de perguntas das atividades. Como conclusões, observou-se que os alunos desenvolveram atitudes autônomas durante seus processos de aprendizagem, fomentando posturas investigativas. Tais atitudes contribuíram na criação e experimentação de diferentes estratégias de resolução o que refletiu nas explorações e investigações realizadas por eles a respeito das ideias associadas ao conceito de função afim. / This research aims to understand how activities involving encryption problems can assist students to explore the ideias associated with affine functions. The activities proposed to the students were structured in the form of enigmas involving tales based on the character Sherlock Holmes, by Sir Arthur Conan Doyle. The activities were developed with a group of students in the first year of high school of the public school E. E. Prof. Mycroft, located in Rio Claro/SP. This work is based on Intervention Research Methodology with Qualitative approach. .Data analysis methodology approaches socio-cultural studies in conjunction with cognitive studies influenced by problem solving and mathematical investigations. As a theoretical framework, the dissertation presents a discussion and reflection about the involvement of mathematics in relation to the powers of fields (social, political, economic, territorial, etc.) always listing this entanglement with the constant evolution of cryptography and its constant search of safe and powerful figures. The research data were produced through observation and by notes in a field diary, carried out by the researcher, in addition to semi-structures interviews and questions cards activities. In conclusion, it was observed that the students developed autonomous attitudes during their learning processes, encouraging investigative positions. Such attitudes have contributed in the creation and experimentation of different resolution strategies, which have reflected on the explorations and investigations that they did about the ideas associated with the concept of affine function.

This work is focused on cipher algorithm AES, his selection method and description of cipher blocks, possibilities of .NET framework and current implementation of AES algorithm in C#. The book also contain complete application for teaching and explanation of AES cipher.