New Directions in Cryptanalysis of Block Ciphers
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Improved Cryptanalysis of the Reduced Grøstl Compression Function, ECHO Permutation and AES Block Cipher
Improved Cryptanalysis of the Reduced Grøstl Compression Function, ECHO Permutation and AES Block Cipher Florian Mendel1, Thomas Peyrin2, Christian Rechberger1, and Martin Schl¨affer1 1 IAIK, Graz University of Technology, Austria 2 Ingenico, France [email protected],[email protected] Abstract. In this paper, we propose two new ways to mount attacks on the SHA-3 candidates Grøstl, and ECHO, and apply these attacks also to the AES. Our results improve upon and extend the rebound attack. Using the new techniques, we are able to extend the number of rounds in which available degrees of freedom can be used. As a result, we present the first attack on 7 rounds for the Grøstl-256 output transformation3 and improve the semi-free-start collision attack on 6 rounds. Further, we present an improved known-key distinguisher for 7 rounds of the AES block cipher and the internal permutation used in ECHO. Keywords: hash function, block cipher, cryptanalysis, semi-free-start collision, known-key distinguisher 1 Introduction Recently, a new wave of hash function proposals appeared, following a call for submissions to the SHA-3 contest organized by NIST [26]. In order to analyze these proposals, the toolbox which is at the cryptanalysts' disposal needs to be extended. Meet-in-the-middle and differential attacks are commonly used. A recent extension of differential cryptanalysis to hash functions is the rebound attack [22] originally applied to reduced (7.5 rounds) Whirlpool (standardized since 2000 by ISO/IEC 10118-3:2004) and a reduced version (6 rounds) of the SHA-3 candidate Grøstl-256 [14], which both have 10 rounds in total. -
The Design of Rijndael: AES - the Advanced Encryption Standard/Joan Daemen, Vincent Rijmen
Joan Daernen · Vincent Rijrnen Theof Design Rijndael AES - The Advanced Encryption Standard With 48 Figures and 17 Tables Springer Berlin Heidelberg New York Barcelona Hong Kong London Milan Paris Springer TnL-1Jn Joan Daemen Foreword Proton World International (PWI) Zweefvliegtuigstraat 10 1130 Brussels, Belgium Vincent Rijmen Cryptomathic NV Lei Sa 3000 Leuven, Belgium Rijndael was the surprise winner of the contest for the new Advanced En cryption Standard (AES) for the United States. This contest was organized and run by the National Institute for Standards and Technology (NIST) be ginning in January 1997; Rij ndael was announced as the winner in October 2000. It was the "surprise winner" because many observers (and even some participants) expressed scepticism that the U.S. government would adopt as Library of Congress Cataloging-in-Publication Data an encryption standard any algorithm that was not designed by U.S. citizens. Daemen, Joan, 1965- Yet NIST ran an open, international, selection process that should serve The design of Rijndael: AES - The Advanced Encryption Standard/Joan Daemen, Vincent Rijmen. as model for other standards organizations. For example, NIST held their p.cm. Includes bibliographical references and index. 1999 AES meeting in Rome, Italy. The five finalist algorithms were designed ISBN 3540425802 (alk. paper) . .. by teams from all over the world. 1. Computer security - Passwords. 2. Data encryption (Computer sCIence) I. RIJmen, In the end, the elegance, efficiency, security, and principled design of Vincent, 1970- II. Title Rijndael won the day for its two Belgian designers, Joan Daemen and Vincent QA76.9.A25 D32 2001 Rijmen, over the competing finalist designs from RSA, IBl\!I, Counterpane 2001049851 005.8-dc21 Systems, and an English/Israeli/Danish team. -
Key-Dependent Approximations in Cryptanalysis. an Application of Multiple Z4 and Non-Linear Approximations
KEY-DEPENDENT APPROXIMATIONS IN CRYPTANALYSIS. AN APPLICATION OF MULTIPLE Z4 AND NON-LINEAR APPROXIMATIONS. FX Standaert, G Rouvroy, G Piret, JJ Quisquater, JD Legat Universite Catholique de Louvain, UCL Crypto Group, Place du Levant, 3, 1348 Louvain-la-Neuve, standaert,rouvroy,piret,quisquater,[email protected] Linear cryptanalysis is a powerful cryptanalytic technique that makes use of a linear approximation over some rounds of a cipher, combined with one (or two) round(s) of key guess. This key guess is usually performed by a partial decryp- tion over every possible key. In this paper, we investigate a particular class of non-linear boolean functions that allows to mount key-dependent approximations of s-boxes. Replacing the classical key guess by these key-dependent approxima- tions allows to quickly distinguish a set of keys including the correct one. By combining different relations, we can make up a system of equations whose solu- tion is the correct key. The resulting attack allows larger flexibility and improves the success rate in some contexts. We apply it to the block cipher Q. In parallel, we propose a chosen-plaintext attack against Q that reduces the required number of plaintext-ciphertext pairs from 297 to 287. 1. INTRODUCTION In its basic version, linear cryptanalysis is a known-plaintext attack that uses a linear relation between input-bits, output-bits and key-bits of an encryption algorithm that holds with a certain probability. If enough plaintext-ciphertext pairs are provided, this approximation can be used to assign probabilities to the possible keys and to locate the most probable one. -
Integral Cryptanalysis on Full MISTY1⋆
Integral Cryptanalysis on Full MISTY1? Yosuke Todo NTT Secure Platform Laboratories, Tokyo, Japan [email protected] Abstract. MISTY1 is a block cipher designed by Matsui in 1997. It was well evaluated and standardized by projects, such as CRYPTREC, ISO/IEC, and NESSIE. In this paper, we propose a key recovery attack on the full MISTY1, i.e., we show that 8-round MISTY1 with 5 FL layers does not have 128-bit security. Many attacks against MISTY1 have been proposed, but there is no attack against the full MISTY1. Therefore, our attack is the first cryptanalysis against the full MISTY1. We construct a new integral characteristic by using the propagation characteristic of the division property, which was proposed in 2015. We first improve the division property by optimizing a public S-box and then construct a 6-round integral characteristic on MISTY1. Finally, we recover the secret key of the full MISTY1 with 263:58 chosen plaintexts and 2121 time complexity. Moreover, if we can use 263:994 chosen plaintexts, the time complexity for our attack is reduced to 2107:9. Note that our cryptanalysis is a theoretical attack. Therefore, the practical use of MISTY1 will not be affected by our attack. Keywords: MISTY1, Integral attack, Division property 1 Introduction MISTY [Mat97] is a block cipher designed by Matsui in 1997 and is based on the theory of provable security [Nyb94,NK95] against differential attack [BS90] and linear attack [Mat93]. MISTY has a recursive structure, and the component function has a unique structure, the so-called MISTY structure [Mat96]. -
Chondrichthyan Fishes (Sharks, Skates, Rays) Announcements
Chondrichthyan Fishes (sharks, skates, rays) Announcements 1. Please review the syllabus for reading and lab information! 2. Please do the readings: for this week posted now. 3. Lab sections: 4. i) Dylan Wainwright, Thursday 2 - 4/5 pm ii) Kelsey Lucas, Friday 2 - 4/5 pm iii) Labs are in the Northwest Building basement (room B141) 4. Lab sections done: first lab this week on Thursday! 5. First lab reading: Agassiz fish story; lab will be a bit shorter 6. Office hours: we’ll set these later this week Please use the course web site: note the various modules Outline Lecture outline: -- Intro. to chondrichthyan phylogeny -- 6 key chondrichthyan defining traits (synapomorphies) -- 3 chondrichthyan behaviors -- Focus on several major groups and selected especially interesting ones 1) Holocephalans (chimaeras or ratfishes) 2) Elasmobranchii (sharks, skates, rays) 3) Batoids (skates, rays, and sawfish) 4) Sharks – several interesting groups Not remotely possible to discuss today all the interesting groups! Vertebrate tree – key ―fish‖ groups Today Chondrichthyan Fishes sharks Overview: 1. Mostly marine 2. ~ 1,200 species 518 species of sharks 650 species of rays 38 species of chimaeras Skates and rays 3. ~ 3 % of all ―fishes‖ 4. Internal skeleton made of cartilage 5. Three major groups 6. Tremendous diversity of behavior and structure and function Chimaeras Chondrichthyan Fishes: 6 key traits Synapomorphy 1: dentition; tooth replacement pattern • Teeth are not fused to jaws • New rows move up to replace old/lost teeth • Chondrichthyan teeth are -
Related-Key Cryptanalysis of 3-WAY, Biham-DES,CAST, DES-X, Newdes, RC2, and TEA
Related-Key Cryptanalysis of 3-WAY, Biham-DES,CAST, DES-X, NewDES, RC2, and TEA John Kelsey Bruce Schneier David Wagner Counterpane Systems U.C. Berkeley kelsey,schneier @counterpane.com [email protected] f g Abstract. We present new related-key attacks on the block ciphers 3- WAY, Biham-DES, CAST, DES-X, NewDES, RC2, and TEA. Differen- tial related-key attacks allow both keys and plaintexts to be chosen with specific differences [KSW96]. Our attacks build on the original work, showing how to adapt the general attack to deal with the difficulties of the individual algorithms. We also give specific design principles to protect against these attacks. 1 Introduction Related-key cryptanalysis assumes that the attacker learns the encryption of certain plaintexts not only under the original (unknown) key K, but also under some derived keys K0 = f(K). In a chosen-related-key attack, the attacker specifies how the key is to be changed; known-related-key attacks are those where the key difference is known, but cannot be chosen by the attacker. We emphasize that the attacker knows or chooses the relationship between keys, not the actual key values. These techniques have been developed in [Knu93b, Bih94, KSW96]. Related-key cryptanalysis is a practical attack on key-exchange protocols that do not guarantee key-integrity|an attacker may be able to flip bits in the key without knowing the key|and key-update protocols that update keys using a known function: e.g., K, K + 1, K + 2, etc. Related-key attacks were also used against rotor machines: operators sometimes set rotors incorrectly. -
An Introduction to the Classification of Elasmobranchs
An introduction to the classification of elasmobranchs 17 Rekha J. Nair and P.U Zacharia Central Marine Fisheries Research Institute, Kochi-682 018 Introduction eyed, stomachless, deep-sea creatures that possess an upper jaw which is fused to its cranium (unlike in sharks). The term Elasmobranchs or chondrichthyans refers to the The great majority of the commercially important species of group of marine organisms with a skeleton made of cartilage. chondrichthyans are elasmobranchs. The latter are named They include sharks, skates, rays and chimaeras. These for their plated gills which communicate to the exterior by organisms are characterised by and differ from their sister 5–7 openings. In total, there are about 869+ extant species group of bony fishes in the characteristics like cartilaginous of elasmobranchs, with about 400+ of those being sharks skeleton, absence of swim bladders and presence of five and the rest skates and rays. Taxonomy is also perhaps to seven pairs of naked gill slits that are not covered by an infamously known for its constant, yet essential, revisions operculum. The chondrichthyans which are placed in Class of the relationships and identity of different organisms. Elasmobranchii are grouped into two main subdivisions Classification of elasmobranchs certainly does not evade this Holocephalii (Chimaeras or ratfishes and elephant fishes) process, and species are sometimes lumped in with other with three families and approximately 37 species inhabiting species, or renamed, or assigned to different families and deep cool waters; and the Elasmobranchii, which is a large, other taxonomic groupings. It is certain, however, that such diverse group (sharks, skates and rays) with representatives revisions will clarify our view of the taxonomy and phylogeny in all types of environments, from fresh waters to the bottom (evolutionary relationships) of elasmobranchs, leading to a of marine trenches and from polar regions to warm tropical better understanding of how these creatures evolved. -
Impossible Differential Cryptanalysis of TEA, XTEA and HIGHT
Preliminaries Impossible Differential Attacks on TEA and XTEA Impossible Differential Cryptanalysis of HIGHT Conclusion Impossible Differential Cryptanalysis of TEA, XTEA and HIGHT Jiazhe Chen1;2 Meiqin Wang1;2 Bart Preneel2 1Shangdong University, China 2KU Leuven, ESAT/COSIC and IBBT, Belgium AfricaCrypt 2012 July 10, 2012 1 / 27 Preliminaries Impossible Differential Attacks on TEA and XTEA Impossible Differential Cryptanalysis of HIGHT Conclusion Preliminaries Impossible Differential Attack TEA, XTEA and HIGHT Impossible Differential Attacks on TEA and XTEA Deriving Impossible Differentials for TEA and XTEA Key Recovery Attacks on TEA and XTEA Impossible Differential Cryptanalysis of HIGHT Impossible Differential Attacks on HIGHT Conclusion 2 / 27 I Pr(∆A ! ∆B) = 1, Pr(∆G ! ∆F) = 1, ∆B 6= ∆F, Pr(∆A ! ∆G) = 0 I Extend the impossible differential forward and backward to attack a block cipher I Guess subkeys in Part I and Part II, if there is a pair meets ∆A and ∆G, then the subkey guess must be wrong P I A B F G II C Preliminaries Impossible Differential Attacks on TEA and XTEA Impossible Differential Cryptanalysis of HIGHT Conclusion Impossible Differential Attack Impossible Differential Attack 3 / 27 I Pr(∆A ! ∆B) = 1, Pr(∆G ! ∆F) = 1, ∆B 6= ∆F, Pr(∆A ! ∆G) = 0 I Extend the impossible differential forward and backward to attack a block cipher I Guess subkeys in Part I and Part II, if there is a pair meets ∆A and ∆G, then the subkey guess must be wrong P I A B F G II C Preliminaries Impossible Differential Attacks on TEA and XTEA Impossible -
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. -
Polish Mathematicians Finding Patterns in Enigma Messages
Fall 2006 Chris Christensen MAT/CSC 483 Machine Ciphers Polyalphabetic ciphers are good ways to destroy the usefulness of frequency analysis. Implementation can be a problem, however. The key to a polyalphabetic cipher specifies the order of the ciphers that will be used during encryption. Ideally there would be as many ciphers as there are letters in the plaintext message and the ordering of the ciphers would be random – an one-time pad. More commonly, some rotation among a small number of ciphers is prescribed. But, rotating among a small number of ciphers leads to a period, which a cryptanalyst can exploit. Rotating among a “large” number of ciphers might work, but that is hard to do by hand – there is a high probability of encryption errors. Maybe, a machine. During World War II, all the Allied and Axis countries used machine ciphers. The United States had SIGABA, Britain had TypeX, Japan had “Purple,” and Germany (and Italy) had Enigma. SIGABA http://en.wikipedia.org/wiki/SIGABA 1 A TypeX machine at Bletchley Park. 2 From the 1920s until the 1970s, cryptology was dominated by machine ciphers. What the machine ciphers typically did was provide a mechanical way to rotate among a large number of ciphers. The rotation was not random, but the large number of ciphers that were available could prevent depth from occurring within messages and (if the machines were used properly) among messages. We will examine Enigma, which was broken by Polish mathematicians in the 1930s and by the British during World War II. The Japanese Purple machine, which was used to transmit diplomatic messages, was broken by William Friedman’s cryptanalysts. -
A Lightweight Encryption Algorithm for Secure Internet of Things
Pre-Print Version, Original article is available at (IJACSA) International Journal of Advanced Computer Science and Applications, Vol. 8, No. 1, 2017 SIT: A Lightweight Encryption Algorithm for Secure Internet of Things Muhammad Usman∗, Irfan Ahmedy, M. Imran Aslamy, Shujaat Khan∗ and Usman Ali Shahy ∗Faculty of Engineering Science and Technology (FEST), Iqra University, Defence View, Karachi-75500, Pakistan. Email: fmusman, [email protected] yDepartment of Electronic Engineering, NED University of Engineering and Technology, University Road, Karachi 75270, Pakistan. Email: firfans, [email protected], [email protected] Abstract—The Internet of Things (IoT) being a promising and apply analytics to share the most valuable data with the technology of the future is expected to connect billions of devices. applications. The IoT is taking the conventional internet, sensor The increased number of communication is expected to generate network and mobile network to another level as every thing mountains of data and the security of data can be a threat. The will be connected to the internet. A matter of concern that must devices in the architecture are essentially smaller in size and be kept under consideration is to ensure the issues related to low powered. Conventional encryption algorithms are generally confidentiality, data integrity and authenticity that will emerge computationally expensive due to their complexity and requires many rounds to encrypt, essentially wasting the constrained on account of security and privacy [4]. energy of the gadgets. Less complex algorithm, however, may compromise the desired integrity. In this paper we propose a A. Applications of IoT: lightweight encryption algorithm named as Secure IoT (SIT). -
Division Property: Efficient Method to Estimate Upper Bound of Algebraic Degree
Division Property: Efficient Method to Estimate Upper Bound of Algebraic Degree Yosuke Todo1;2 1 NTT Secure Platform Laboratories, Tokyo, Japan [email protected] 2 Kobe University, Kobe, Japan Abstract. We proposed the division property, which is a new method to find integral characteristics, at EUROCRYPT 2015. In this paper, we expound the division property, its effectiveness, and follow-up results. Higher-Order Differential and Integral Cryptanalyses. After the pro- posal of the differential cryptanalysis [1], many extended cryptanalyses have been proposed. The higher-order differential cryptanalysis is one of such extensions. The concept was first introduced by Lai [6] and the advantage over the classical differential cryptanalysis was studied by Knudsen [4]. Assuming the algebraic degree of the target block cipher Ek is upper-bounded by d for any k, the dth order differential is always constant. Then, we can distinguish the target cipher Ek as ideal block ciphers because it is unlikely that ideal block ciphers have such property, and we call this property the higher-order differential characteristics in this paper. The similar technique to the higher-order differential cryptanalysis was used as the dedicated attack against the block cipher Square [3], and the dedicated attack was later referred to the square attack. In 2002, Knudsen and Wagner formalized the square attack as the integral cryptanalysis [5]. In the integral cryptanalysis, attackers first prepare N chosen plaintexts. If the XOR of all cor- responding ciphertexts is 0, we say that the cipher has an integral characteristic with N chosen plaintexts. The integral characteristic is found by evaluating the propagation of four integral properties: A, C, B, and U.