A Brief Outlook at Block Ciphers
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Vector Boolean Functions: Applications in Symmetric Cryptography
Vector Boolean Functions: Applications in Symmetric Cryptography José Antonio Álvarez Cubero Departamento de Matemática Aplicada a las Tecnologías de la Información y las Comunicaciones Universidad Politécnica de Madrid This dissertation is submitted for the degree of Doctor Ingeniero de Telecomunicación Escuela Técnica Superior de Ingenieros de Telecomunicación November 2015 I would like to thank my wife, Isabel, for her love, kindness and support she has shown during the past years it has taken me to finalize this thesis. Furthermore I would also liketo thank my parents for their endless love and support. Last but not least, I would like to thank my loved ones such as my daughter and sisters who have supported me throughout entire process, both by keeping me harmonious and helping me putting pieces together. I will be grateful forever for your love. Declaration The following papers have been published or accepted for publication, and contain material based on the content of this thesis. 1. [7] Álvarez-Cubero, J. A. and Zufiria, P. J. (expected 2016). Algorithm xxx: VBF: A library of C++ classes for vector Boolean functions in cryptography. ACM Transactions on Mathematical Software. (In Press: http://toms.acm.org/Upcoming.html) 2. [6] Álvarez-Cubero, J. A. and Zufiria, P. J. (2012). Cryptographic Criteria on Vector Boolean Functions, chapter 3, pages 51–70. Cryptography and Security in Computing, Jaydip Sen (Ed.), http://www.intechopen.com/books/cryptography-and-security-in-computing/ cryptographic-criteria-on-vector-boolean-functions. (Published) 3. [5] Álvarez-Cubero, J. A. and Zufiria, P. J. (2010). A C++ class for analysing vector Boolean functions from a cryptographic perspective. -
Chapter 3 – Block Ciphers and the Data Encryption Standard
Chapter 3 –Block Ciphers and the Data Cryptography and Network Encryption Standard Security All the afternoon Mungo had been working on Stern's Chapter 3 code, principally with the aid of the latest messages which he had copied down at the Nevin Square drop. Stern was very confident. He must be well aware London Central knew about that drop. It was obvious Fifth Edition that they didn't care how often Mungo read their messages, so confident were they in the by William Stallings impenetrability of the code. —Talking to Strange Men, Ruth Rendell Lecture slides by Lawrie Brown Modern Block Ciphers Block vs Stream Ciphers now look at modern block ciphers • block ciphers process messages in blocks, each one of the most widely used types of of which is then en/decrypted cryptographic algorithms • like a substitution on very big characters provide secrecy /hii/authentication services – 64‐bits or more focus on DES (Data Encryption Standard) • stream ciphers process messages a bit or byte at a time when en/decrypting to illustrate block cipher design principles • many current ciphers are block ciphers – better analysed – broader range of applications Block vs Stream Ciphers Block Cipher Principles • most symmetric block ciphers are based on a Feistel Cipher Structure • needed since must be able to decrypt ciphertext to recover messages efficiently • bloc k cihiphers lklook like an extremely large substitution • would need table of 264 entries for a 64‐bit block • instead create from smaller building blocks • using idea of a product cipher 1 Claude -
Indistinguishability Amplification
Indistinguishability Amplification Ueli Maurer Krzysztof Pietrzak Renato Renner [email protected] [email protected] [email protected] ETH Z¨urich ENS Paris Cambridge Abstract A random system is the abstraction of the input-output behavior of any kind of discrete system, in particular cryptographic systems. Many aspects of cryptographic security analyses and proofs can be seen as the proof that a certain random system (e.g. a block cipher) is indistinguishable from an ideal system (e.g. a random permutation), for different types of distinguishers. This paper presents a new generic approach to proving upper bounds on the distinguishing ad- vantage of a combined system, assuming upper bounds of various types on the component systems. For a general type of combination operation of systems (including the combination of functions or the cascade of permutations), we prove two amplification theorems. The first is a direct-product theorem, similar in spirit to the XOR-Lemma: The distinguishing advantage (or security) of the combination of two (possibly stateful) systems is twice the product of the individual distinguishing advantages, which is optimal. The second theorem states that the combination of systems is secure against some strong class of distinguishers, assuming only that the components are secure against some weaker class of attacks. As a corollary we obtain tight bounds on the adaptive security of the cascade and parallel composition of non-adaptively (or only random-query) secure component systems. A key technical tool of the paper is to show a tight two-way correspondence, previously only known to hold in one direction, between the distinguishing advantage of two systems and the probability of provoking an appropriately defined event on one of the systems. -
BOUNDARY LAYERS with FLOW REVERSAL John F. Nush
NASA CONTRACTOR REPORT FURTHER STUDIES OF UNSTEADY BOUNDARY LAYERS WITH FLOW REVERSAL John F. Nush Prepared by SYBUCON, INC. Atlanta, Ga. 303 39 for Ames Research Center TECH LIBRARY KAFB, NU NASA CR-2767 I I 4. Title nd Subtitle I 5. Report Date "Further Studies of Unsteady Boundary Layers with . December 1976 Flow Reversalll Organization 6. Performing Code 7. Author($) 8. Performing Orgnization Report No. John F. Nash 10. Work Unit No. 9. Performing Orpmization Nama and Address Sybucon, Inc. 11.Contract or GrantNo. 9 960) Perimeter Place,N.W. (Suite 2-8771 Atlanta, Georgia 30339 - NAS 13.Type of Report andPeriod Covered 12. Sponsoring myName md Address 6 Contractor Report- National Aeronautics Space Administration 14.Sponsorirg Aqmcy Code Washington, D. C. 20546 I 15.Supplementary Notas 16. Abstract Further computational experiments have been conducted to study the charac- teristics of flow reversal and separation in unsteady boundary layers. One set of calculations was performed using thefirst-order, time-dependent turbulent boundary-layer equations, and extended earlier work by Nash and Pate1 to a wider rangeof flows. Another set of calculations was performed for laminar flow using the time-dependent Navier-Stokesequati.ons. 1 The results of the calculations confirm previous conclusions concerning the existence of a regime of unseparated flow, containing an embedded regionof reversal, which is accessible to first-order boundary-layer theory.However certain doubts are caston the precise natureof the events which accompany the eventual breakdownof the theory due to singularity onset.The earlier view that the singularity appearsas the final event in a sequence involving rapid thickeningof the boundary layer and the formationof a localized region of steep gradients, is called into questionby the present results. -
("DSCC") Files This Complaint Seeking an Immediate Investigation by the 7
COMPLAINT BEFORE THE FEDERAL ELECTION CBHMISSIOAl INTRODUCTXON - 1 The Democratic Senatorial Campaign Committee ("DSCC") 7-_. J _j. c files this complaint seeking an immediate investigation by the 7 c; a > Federal Election Commission into the illegal spending A* practices of the National Republican Senatorial Campaign Committee (WRSCIt). As the public record shows, and an investigation will confirm, the NRSC and a series of ostensibly nonprofit, nonpartisan groups have undertaken a significant and sustained effort to funnel "soft money101 into federal elections in violation of the Federal Election Campaign Act of 1971, as amended or "the Act"), 2 U.S.C. 5s 431 et seq., and the Federal Election Commission (peFECt)Regulations, 11 C.F.R. 85 100.1 & sea. 'The term "aoft money" as ueed in this Complaint means funds,that would not be lawful for use in connection with any federal election (e.g., corporate or labor organization treasury funds, contributions in excess of the relevant contribution limit for federal elections). THE FACTS IN TBIS CABE On November 24, 1992, the state of Georgia held a unique runoff election for the office of United States Senator. Georgia law provided for a runoff if no candidate in the regularly scheduled November 3 general election received in excess of 50 percent of the vote. The 1992 runoff in Georg a was a hotly contested race between the Democratic incumbent Wyche Fowler, and his Republican opponent, Paul Coverdell. The Republicans presented this election as a %ust-win81 election. Exhibit 1. The Republicans were so intent on victory that Senator Dole announced he was willing to give up his seat on the Senate Agriculture Committee for Coverdell, if necessary. -
On the Decorrelated Fast Cipher (DFC) and Its Theory
On the Decorrelated Fast Cipher (DFC) and Its Theory Lars R. Knudsen and Vincent Rijmen ? Department of Informatics, University of Bergen, N-5020 Bergen Abstract. In the first part of this paper the decorrelation theory of Vaudenay is analysed. It is shown that the theory behind the propo- sed constructions does not guarantee security against state-of-the-art differential attacks. In the second part of this paper the proposed De- correlated Fast Cipher (DFC), a candidate for the Advanced Encryption Standard, is analysed. It is argued that the cipher does not obtain prova- ble security against a differential attack. Also, an attack on DFC reduced to 6 rounds is given. 1 Introduction In [6,7] a new theory for the construction of secret-key block ciphers is given. The notion of decorrelation to the order d is defined. Let C be a block cipher with block size m and C∗ be a randomly chosen permutation in the same message space. If C has a d-wise decorrelation equal to that of C∗, then an attacker who knows at most d − 1 pairs of plaintexts and ciphertexts cannot distinguish between C and C∗. So, the cipher C is “secure if we use it only d−1 times” [7]. It is further noted that a d-wise decorrelated cipher for d = 2 is secure against both a basic linear and a basic differential attack. For the latter, this basic attack is as follows. A priori, two values a and b are fixed. Pick two plaintexts of difference a and get the corresponding ciphertexts. -
A Preliminary Empirical Study to Compare MPI and Openmp ISI-TR-676
A preliminary empirical study to compare MPI and OpenMP ISI-TR-676 Lorin Hochstein, Victor R. Basili December 2011 Abstract Context: The rise of multicore is bringing shared-memory parallelism to the masses. The community is struggling to identify which parallel models are most productive. Objective: Measure the effect of MPI and OpenMP models on programmer productivity. Design: One group of programmers solved the sharks and fishes problem using MPI and a second group solved the same problem using OpenMP, then each programmer switched models and solved the same problem again. The participants were graduate students in an HPC course. Measures: Development effort (hours), program correctness (grades), pro- gram performance (speedup versus serial implementation). Results: Mean OpenMP development time was 9.6 hours less than MPI (95% CI, 0.37 − 19 hours), a 43% reduction. No statistically significant difference was observed in assignment grades. MPI performance was better than OpenMP performance for 4 out of the 5 students that submitted correct implementations for both models. Conclusions: OpenMP solutions for this problem required less effort than MPI, but insufficient power to measure the effect on correctness. The perfor- mance data was insufficient to draw strong conclusions but suggests that unop- timized MPI programs perform better than unoptimized OpenMP programs, even with a similar parallelization strategy. Further studies are necessary to examine different programming problems, models, and levels of programmer experience. Chapter 1 INTRODUCTION In the high-performance computing community, the dominant parallel pro- gramming model today is MPI, with OpenMP as a distant but clear second place [1,2]. MPI’s advantage over OpenMP on distributed memory systems is well-known, and consequently MPI usage dominates in large-scale HPC sys- tems. -
Report on the AES Candidates
Rep ort on the AES Candidates 1 2 1 3 Olivier Baudron , Henri Gilb ert , Louis Granb oulan , Helena Handschuh , 4 1 5 1 Antoine Joux , Phong Nguyen ,Fabrice Noilhan ,David Pointcheval , 1 1 1 1 Thomas Pornin , Guillaume Poupard , Jacques Stern , and Serge Vaudenay 1 Ecole Normale Sup erieure { CNRS 2 France Telecom 3 Gemplus { ENST 4 SCSSI 5 Universit e d'Orsay { LRI Contact e-mail: [email protected] Abstract This do cument rep orts the activities of the AES working group organized at the Ecole Normale Sup erieure. Several candidates are evaluated. In particular we outline some weaknesses in the designs of some candidates. We mainly discuss selection criteria b etween the can- didates, and make case-by-case comments. We nally recommend the selection of Mars, RC6, Serp ent, ... and DFC. As the rep ort is b eing nalized, we also added some new preliminary cryptanalysis on RC6 and Crypton in the App endix which are not considered in the main b o dy of the rep ort. Designing the encryption standard of the rst twentyyears of the twenty rst century is a challenging task: we need to predict p ossible future technologies, and wehavetotake unknown future attacks in account. Following the AES pro cess initiated by NIST, we organized an op en working group at the Ecole Normale Sup erieure. This group met two hours a week to review the AES candidates. The present do cument rep orts its results. Another task of this group was to up date the DFC candidate submitted by CNRS [16, 17] and to answer questions which had b een omitted in previous 1 rep orts on DFC. -
Chapter 3 – Block Ciphers and the Data Encryption Standard
Symmetric Cryptography Chapter 6 Block vs Stream Ciphers • Block ciphers process messages into blocks, each of which is then en/decrypted – Like a substitution on very big characters • 64-bits or more • Stream ciphers process messages a bit or byte at a time when en/decrypting – Many current ciphers are block ciphers • Better analyzed. • Broader range of applications. Block vs Stream Ciphers Block Cipher Principles • Block ciphers look like an extremely large substitution • Would need table of 264 entries for a 64-bit block • Arbitrary reversible substitution cipher for a large block size is not practical – 64-bit general substitution block cipher, key size 264! • Most symmetric block ciphers are based on a Feistel Cipher Structure • Needed since must be able to decrypt ciphertext to recover messages efficiently Ideal Block Cipher Substitution-Permutation Ciphers • in 1949 Shannon introduced idea of substitution- permutation (S-P) networks – modern substitution-transposition product cipher • These form the basis of modern block ciphers • S-P networks are based on the two primitive cryptographic operations we have seen before: – substitution (S-box) – permutation (P-box) (transposition) • Provide confusion and diffusion of message Diffusion and Confusion • Introduced by Claude Shannon to thwart cryptanalysis based on statistical analysis – Assume the attacker has some knowledge of the statistical characteristics of the plaintext • Cipher needs to completely obscure statistical properties of original message • A one-time pad does this Diffusion -
A Tutorial on the Implementation of Block Ciphers: Software and Hardware Applications
A Tutorial on the Implementation of Block Ciphers: Software and Hardware Applications Howard M. Heys Memorial University of Newfoundland, St. John's, Canada email: [email protected] Dec. 10, 2020 2 Abstract In this article, we discuss basic strategies that can be used to implement block ciphers in both software and hardware environments. As models for discussion, we use substitution- permutation networks which form the basis for many practical block cipher structures. For software implementation, we discuss approaches such as table lookups and bit-slicing, while for hardware implementation, we examine a broad range of architectures from high speed structures like pipelining, to compact structures based on serialization. To illustrate different implementation concepts, we present example data associated with specific methods and discuss sample designs that can be employed to realize different implementation strategies. We expect that the article will be of particular interest to researchers, scientists, and engineers that are new to the field of cryptographic implementation. 3 4 Terminology and Notation Abbreviation Definition SPN substitution-permutation network IoT Internet of Things AES Advanced Encryption Standard ECB electronic codebook mode CBC cipher block chaining mode CTR counter mode CMOS complementary metal-oxide semiconductor ASIC application-specific integrated circuit FPGA field-programmable gate array Table 1: Abbreviations Used in Article 5 6 Variable Definition B plaintext/ciphertext block size (also, size of cipher state) κ number -
Symmetric Key Ciphers Objectives
Symmetric Key Ciphers Debdeep Mukhopadhyay Assistant Professor Department of Computer Science and Engineering Indian Institute of Technology Kharagpur INDIA -721302 Objectives • Definition of Symmetric Types of Symmetric Key ciphers – Modern Block Ciphers • Full Size and Partial Size Key Ciphers • Components of a Modern Block Cipher – PBox (Permutation Box) – SBox (Substitution Box) –Swap – Properties of the Exclusive OR operation • Diffusion and Confusion • Types of Block Ciphers: Feistel and non-Feistel ciphers D. Mukhopadhyay Crypto & Network Security IIT Kharagpur 1 Symmetric Key Setting Communication Message Channel Message E D Ka Kb Bob Alice Assumptions Eve Ka is the encryption key, Kb is the decryption key. For symmetric key ciphers, Ka=Kb - Only Alice and Bob knows Ka (or Kb) - Eve has access to E, D and the Communication Channel but does not know the key Ka (or Kb) Types of symmetric key ciphers • Block Ciphers: Symmetric key ciphers, where a block of data is encrypted • Stream Ciphers: Symmetric key ciphers, where block size=1 D. Mukhopadhyay Crypto & Network Security IIT Kharagpur 2 Block Ciphers Block Cipher • A symmetric key modern cipher encrypts an n bit block of plaintext or decrypts an n bit block of ciphertext. •Padding: – If the message has fewer than n bits, padding must be done to make it n bits. – If the message size is not a multiple of n, then it should be divided into n bit blocks and the last block should be padded. D. Mukhopadhyay Crypto & Network Security IIT Kharagpur 3 Full Size Key Ciphers • Transposition Ciphers: – Involves rearrangement of bits, without changing value. – Consider an n bit cipher – How many such rearrangements are possible? •n! – How many key bits are necessary? • ceil[log2 (n!)] Full Size Key Ciphers • Substitution Ciphers: – It does not transpose bits, but substitutes values – Can we model this as a permutation? – Yes. -
Security Evaluation of the K2 Stream Cipher
Security Evaluation of the K2 Stream Cipher Editors: Andrey Bogdanov, Bart Preneel, and Vincent Rijmen Contributors: Andrey Bodganov, Nicky Mouha, Gautham Sekar, Elmar Tischhauser, Deniz Toz, Kerem Varıcı, Vesselin Velichkov, and Meiqin Wang Katholieke Universiteit Leuven Department of Electrical Engineering ESAT/SCD-COSIC Interdisciplinary Institute for BroadBand Technology (IBBT) Kasteelpark Arenberg 10, bus 2446 B-3001 Leuven-Heverlee, Belgium Version 1.1 | 7 March 2011 i Security Evaluation of K2 7 March 2011 Contents 1 Executive Summary 1 2 Linear Attacks 3 2.1 Overview . 3 2.2 Linear Relations for FSR-A and FSR-B . 3 2.3 Linear Approximation of the NLF . 5 2.4 Complexity Estimation . 5 3 Algebraic Attacks 6 4 Correlation Attacks 10 4.1 Introduction . 10 4.2 Combination Generators and Linear Complexity . 10 4.3 Description of the Correlation Attack . 11 4.4 Application of the Correlation Attack to KCipher-2 . 13 4.5 Fast Correlation Attacks . 14 5 Differential Attacks 14 5.1 Properties of Components . 14 5.1.1 Substitution . 15 5.1.2 Linear Permutation . 15 5.2 Key Ideas of the Attacks . 18 5.3 Related-Key Attacks . 19 5.4 Related-IV Attacks . 20 5.5 Related Key/IV Attacks . 21 5.6 Conclusion and Remarks . 21 6 Guess-and-Determine Attacks 25 6.1 Word-Oriented Guess-and-Determine . 25 6.2 Byte-Oriented Guess-and-Determine . 27 7 Period Considerations 28 8 Statistical Properties 29 9 Distinguishing Attacks 31 9.1 Preliminaries . 31 9.2 Mod n Cryptanalysis of Weakened KCipher-2 . 32 9.2.1 Other Reduced Versions of KCipher-2 .