A Pattern Recognition Approach to Block Cipher
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Improved Related-Key Attacks on DESX and DESX+
Improved Related-key Attacks on DESX and DESX+ Raphael C.-W. Phan1 and Adi Shamir3 1 Laboratoire de s´ecurit´eet de cryptographie (LASEC), Ecole Polytechnique F´ed´erale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland [email protected] 2 Faculty of Mathematics & Computer Science, The Weizmann Institute of Science, Rehovot 76100, Israel [email protected] Abstract. In this paper, we present improved related-key attacks on the original DESX, and DESX+, a variant of the DESX with its pre- and post-whitening XOR operations replaced with addition modulo 264. Compared to previous results, our attack on DESX has reduced text complexity, while our best attack on DESX+ eliminates the memory requirements at the same processing complexity. Keywords: DESX, DESX+, related-key attack, fault attack. 1 Introduction Due to the DES’ small key length of 56 bits, variants of the DES under multiple encryption have been considered, including double-DES under one or two 56-bit key(s), and triple-DES under two or three 56-bit keys. Another popular variant based on the DES is the DESX [15], where the basic keylength of single DES is extended to 120 bits by wrapping this DES with two outer pre- and post-whitening keys of 64 bits each. Also, the endorsement of single DES had been officially withdrawn by NIST in the summer of 2004 [19], due to its insecurity against exhaustive search. Future use of single DES is recommended only as a component of the triple-DES. This makes it more important to study the security of variants of single DES which increase the key length to avoid this attack. -
Models and Algorithms for Physical Cryptanalysis
MODELS AND ALGORITHMS FOR PHYSICAL CRYPTANALYSIS Dissertation zur Erlangung des Grades eines Doktor-Ingenieurs der Fakult¨at fur¨ Elektrotechnik und Informationstechnik an der Ruhr-Universit¨at Bochum von Kerstin Lemke-Rust Bochum, Januar 2007 ii Thesis Advisor: Prof. Dr.-Ing. Christof Paar, Ruhr University Bochum, Germany External Referee: Prof. Dr. David Naccache, Ecole´ Normale Sup´erieure, Paris, France Author contact information: [email protected] iii Abstract This thesis is dedicated to models and algorithms for the use in physical cryptanalysis which is a new evolving discipline in implementation se- curity of information systems. It is based on physically observable and manipulable properties of a cryptographic implementation. Physical observables, such as the power consumption or electromag- netic emanation of a cryptographic device are so-called `side channels'. They contain exploitable information about internal states of an imple- mentation at runtime. Physical effects can also be used for the injec- tion of faults. Fault injection is successful if it recovers internal states by examining the effects of an erroneous state propagating through the computation. This thesis provides a unified framework for side channel and fault cryptanalysis. Its objective is to improve the understanding of physi- cally enabled cryptanalysis and to provide new models and algorithms. A major motivation for this work is that methodical improvements for physical cryptanalysis can also help in developing efficient countermea- sures for securing cryptographic implementations. This work examines differential side channel analysis of boolean and arithmetic operations which are typical primitives in cryptographic algo- rithms. Different characteristics of these operations can support a side channel analysis, even of unknown ciphers. -
Serpent: a Proposal for the Advanced Encryption Standard
Serpent: A Proposal for the Advanced Encryption Standard Ross Anderson1 Eli Biham2 Lars Knudsen3 1 Cambridge University, England; email [email protected] 2 Technion, Haifa, Israel; email [email protected] 3 University of Bergen, Norway; email [email protected] Abstract. We propose a new block cipher as a candidate for the Ad- vanced Encryption Standard. Its design is highly conservative, yet still allows a very efficient implementation. It uses S-boxes similar to those of DES in a new structure that simultaneously allows a more rapid avalanche, a more efficient bitslice implementation, and an easy anal- ysis that enables us to demonstrate its security against all known types of attack. With a 128-bit block size and a 256-bit key, it is as fast as DES on the market leading Intel Pentium/MMX platforms (and at least as fast on many others); yet we believe it to be more secure than three-key triple-DES. 1 Introduction For many applications, the Data Encryption Standard algorithm is nearing the end of its useful life. Its 56-bit key is too small, as shown by a recent distributed key search exercise [28]. Although triple-DES can solve the key length problem, the DES algorithm was also designed primarily for hardware encryption, yet the great majority of applications that use it today implement it in software, where it is relatively inefficient. For these reasons, the US National Institute of Standards and Technology has issued a call for a successor algorithm, to be called the Advanced Encryption Standard or AES. -
Data Encryption Standard
Data Encryption Standard The Data Encryption Standard (DES /ˌdiːˌiːˈɛs, dɛz/) is a Data Encryption Standard symmetric-key algorithm for the encryption of electronic data. Although insecure, it was highly influential in the advancement of modern cryptography. Developed in the early 1970s atIBM and based on an earlier design by Horst Feistel, the algorithm was submitted to the National Bureau of Standards (NBS) following the agency's invitation to propose a candidate for the protection of sensitive, unclassified electronic government data. In 1976, after consultation with theNational Security Agency (NSA), the NBS eventually selected a slightly modified version (strengthened against differential cryptanalysis, but weakened against brute-force attacks), which was published as an official Federal Information Processing Standard (FIPS) for the United States in 1977. The publication of an NSA-approved encryption standard simultaneously resulted in its quick international adoption and widespread academic scrutiny. Controversies arose out of classified The Feistel function (F function) of DES design elements, a relatively short key length of the symmetric-key General block cipher design, and the involvement of the NSA, nourishing Designers IBM suspicions about a backdoor. Today it is known that the S-boxes that had raised those suspicions were in fact designed by the NSA to First 1975 (Federal Register) actually remove a backdoor they secretly knew (differential published (standardized in January 1977) cryptanalysis). However, the NSA also ensured that the key size was Derived Lucifer drastically reduced such that they could break it by brute force from [2] attack. The intense academic scrutiny the algorithm received over Successors Triple DES, G-DES, DES-X, time led to the modern understanding of block ciphers and their LOKI89, ICE cryptanalysis. -
On the Related-Key Attacks Against Aes*
THE PUBLISHING HOUSE PROCEEDINGS OF THE ROMANIAN ACADEMY, Series A, OF THE ROMANIAN ACADEMY Volume 13, Number 4/2012, pp. 395–400 ON THE RELATED-KEY ATTACKS AGAINST AES* Joan DAEMEN1, Vincent RIJMEN2 1 STMicroElectronics, Belgium 2 KU Leuven & IBBT (Belgium), Graz University of Technology, Austria E-mail: [email protected] Alex Biryukov and Dmitry Khovratovich presented related-key attacks on AES and reduced-round versions of AES. The most impressive of these were presented at Asiacrypt 2009: related-key attacks against the full AES-256 and AES-192. We discuss the applicability of these attacks and related-key attacks in general. We model the access of the attacker to the key in the form of key access schemes. Related-key attacks should only be considered with respect to sound key access schemes. We show that defining a sound key access scheme in which the related-key attacks against AES-256 and AES- 192 can be conducted, is possible, but contrived. Key words: Advanced Encryption Standard, AES, security, related-key attacks. 1. INTRODUCTION Since the start of the process to select the Advanced Encryption Standard (AES), the block cipher Rijndael, which later became the AES, has been scrutinized extensively for security weaknesses. The initial cryptanalytic results can be grouped into three categories. The first category contains attacks variants that were weakened by reducing the number of rounds [0]. The second category contains observations on mathematical properties of sub-components of the AES, which don’t lead to a cryptanalytic attack [0]. The third category consists of side-channel attacks, which target deficiencies in hardware or software implementations [0]. -
Identifying Open Research Problems in Cryptography by Surveying Cryptographic Functions and Operations 1
International Journal of Grid and Distributed Computing Vol. 10, No. 11 (2017), pp.79-98 http://dx.doi.org/10.14257/ijgdc.2017.10.11.08 Identifying Open Research Problems in Cryptography by Surveying Cryptographic Functions and Operations 1 Rahul Saha1, G. Geetha2, Gulshan Kumar3 and Hye-Jim Kim4 1,3School of Computer Science and Engineering, Lovely Professional University, Punjab, India 2Division of Research and Development, Lovely Professional University, Punjab, India 4Business Administration Research Institute, Sungshin W. University, 2 Bomun-ro 34da gil, Seongbuk-gu, Seoul, Republic of Korea Abstract Cryptography has always been a core component of security domain. Different security services such as confidentiality, integrity, availability, authentication, non-repudiation and access control, are provided by a number of cryptographic algorithms including block ciphers, stream ciphers and hash functions. Though the algorithms are public and cryptographic strength depends on the usage of the keys, the ciphertext analysis using different functions and operations used in the algorithms can lead to the path of revealing a key completely or partially. It is hard to find any survey till date which identifies different operations and functions used in cryptography. In this paper, we have categorized our survey of cryptographic functions and operations in the algorithms in three categories: block ciphers, stream ciphers and cryptanalysis attacks which are executable in different parts of the algorithms. This survey will help the budding researchers in the society of crypto for identifying different operations and functions in cryptographic algorithms. Keywords: cryptography; block; stream; cipher; plaintext; ciphertext; functions; research problems 1. Introduction Cryptography [1] in the previous time was analogous to encryption where the main task was to convert the readable message to an unreadable format. -
A Practical Attack on the Fixed RC4 in the WEP Mode
A Practical Attack on the Fixed RC4 in the WEP Mode Itsik Mantin NDS Technologies, Israel [email protected] Abstract. In this paper we revisit a known but ignored weakness of the RC4 keystream generator, where secret state info leaks to the gen- erated keystream, and show that this leakage, also known as Jenkins’ correlation or the RC4 glimpse, can be used to attack RC4 in several modes. Our main result is a practical key recovery attack on RC4 when an IV modifier is concatenated to the beginning of a secret root key to generate a session key. As opposed to the WEP attack from [FMS01] the new attack is applicable even in the case where the first 256 bytes of the keystream are thrown and its complexity grows only linearly with the length of the key. In an exemplifying parameter setting the attack recov- ersa16-bytekeyin248 steps using 217 short keystreams generated from different chosen IVs. A second attacked mode is when the IV succeeds the secret root key. We mount a key recovery attack that recovers the secret root key by analyzing a single word from 222 keystreams generated from different IVs, improving the attack from [FMS01] on this mode. A third result is an attack on RC4 that is applicable when the attacker can inject faults to the execution of RC4. The attacker derives the internal state and the secret key by analyzing 214 faulted keystreams generated from this key. Keywords: RC4, Stream ciphers, Cryptanalysis, Fault analysis, Side- channel attacks, Related IV attacks, Related key attacks. 1 Introduction RC4 is the most widely used stream cipher in software applications. -
Deep Learning-Based Cryptanalysis of Lightweight Block Ciphers
Hindawi Security and Communication Networks Volume 2020, Article ID 3701067, 11 pages https://doi.org/10.1155/2020/3701067 Research Article Deep Learning-Based Cryptanalysis of Lightweight Block Ciphers Jaewoo So Department of Electronic Engineering, Sogang University, Seoul 04107, Republic of Korea Correspondence should be addressed to Jaewoo So; [email protected] Received 5 February 2020; Revised 21 June 2020; Accepted 26 June 2020; Published 13 July 2020 Academic Editor: Umar M. Khokhar Copyright © 2020 Jaewoo So. +is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Most of the traditional cryptanalytic technologies often require a great amount of time, known plaintexts, and memory. +is paper proposes a generic cryptanalysis model based on deep learning (DL), where the model tries to find the key of block ciphers from known plaintext-ciphertext pairs. We show the feasibility of the DL-based cryptanalysis by attacking on lightweight block ciphers such as simplified DES, Simon, and Speck. +e results show that the DL-based cryptanalysis can successfully recover the key bits when the keyspace is restricted to 64 ASCII characters. +e traditional cryptanalysis is generally performed without the keyspace restriction, but only reduced-round variants of Simon and Speck are successfully attacked. Although a text-based key is applied, the proposed DL-based cryptanalysis can successfully break the full rounds of Simon32/64 and Speck32/64. +e results indicate that the DL technology can be a useful tool for the cryptanalysis of block ciphers when the keyspace is restricted. -
Public Evaluation Report UEA2/UIA2
ETSI/SAGE Version: 2.0 Technical report Date: 9th September, 2011 Specification of the 3GPP Confidentiality and Integrity Algorithms 128-EEA3 & 128-EIA3. Document 4: Design and Evaluation Report LTE Confidentiality and Integrity Algorithms 128-EEA3 & 128-EIA3. page 1 of 43 Document 4: Design and Evaluation report. Version 2.0 Document History 0.1 20th June 2010 First draft of main technical text 1.0 11th August 2010 First public release 1.1 11th August 2010 A few typos corrected and text improved 1.2 4th January 2011 A modification of ZUC and 128-EIA3 and text improved 1.3 18th January 2011 Further text improvements including better reference to different historic versions of the algorithms 1.4 1st July 2011 Add a new section on timing attacks 2.0 9th September 2011 Final deliverable LTE Confidentiality and Integrity Algorithms 128-EEA3 & 128-EIA3. page 2 of 43 Document 4: Design and Evaluation report. Version 2.0 Reference Keywords 3GPP, security, SAGE, algorithm ETSI Secretariat Postal address F-06921 Sophia Antipolis Cedex - FRANCE Office address 650 Route des Lucioles - Sophia Antipolis Valbonne - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88 X.400 c= fr; a=atlas; p=etsi; s=secretariat Internet [email protected] http://www.etsi.fr Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. -
Eindhoven University of Technology MASTER Renewal Periods For
Eindhoven University of Technology MASTER Renewal periods for cryptographic keys Posea, S. Award date: 2012 Link to publication Disclaimer This document contains a student thesis (bachelor's or master's), as authored by a student at Eindhoven University of Technology. Student theses are made available in the TU/e repository upon obtaining the required degree. The grade received is not published on the document as presented in the repository. The required complexity or quality of research of student theses may vary by program, and the required minimum study period may vary in duration. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain Renewal Periods for Cryptographic Keys Simona Posea August 2012 Eindhoven University of Technology Department of Mathematics and Computer Science Master's Thesis Renewal Periods for Cryptographic Keys Simona Posea Supervisors: dr. ir. L.A.M. (Berry) Schoenmakers (TU/e - W&I) drs. D.M. Wieringa RE CISSP (Deloitte - S&P) H. Hambartsumyan MSc. CISA (Deloitte - S&P) Eindhoven, August 2012 Abstract Periodically changing cryptographic keys is a common practice. Standards and publications recommending how long a key may be used before it should be renewed are available for guidance. -
On Matsui's Linear Cryptanalysis Eli Biham Computer Science Department Technion - Israel Institute of Technology Haifa 32000, Israel
On Matsui's Linear Cryptanalysis Eli Biham Computer Science Department Technion - Israel Institute of Technology Haifa 32000, Israel Abstract In [9] Matsui introduced a new method of cryptanalysis, called Linear Crypt- analysis. This method was used to attack DES using 24z known plaintexts. In this paper we formalize this method and show that although in the details level this method is quite different from differential crypta~alysis, in the structural level they are very similar. For example, characteristics can be defined in lin- ear cryptanalysis, but the concatenation rule has several important differences from the concatenation rule of differential cryptanalysis. We show that the attack of Davies on DES is closely related to linear cryptanalysis. We describe constraints on the size of S boxes caused by linear cryptanalysis. New results to Feal are also described. 1 Introduction In EUR.OCRYPT'93 Matsui introduced a new method of cryptanalysis, called Linear Cryptanalysis [9]. This method was used to attack DES using 24r known plaintexts. In this paper we formalize this method and show that although in the details level this method is quite different from differential cryptanalysis[2,1], in the structural level they are very similar. For example, characteristics can be defined in linear cryptanalysis, but the concatenation rule has several important differences from the concatenation rule of differential cryptanalysis. We show that the attack of Davies[5] on DES is closely related to linear cryptanalysis. We describe constraints on the size of S boxes caused by linear cryptanalysis. New results to Feal[15,11] are also described. 2 Overview of Linear Cryptanalysis Linear cryptanalysis studies statistical linear relations between bits of the plaintexts, the ciphertexts and the keys they are encrypted under. -
Practical Attacks Against CCA2 Secure Cryptosystems, and Countermeasures
Modi¯ed Parameter Attacks: Practical Attacks Against CCA2 Secure Cryptosystems, and Countermeasures Nick Howgrave-Graham, Joe Silverman, Ari Singer, William Whyte NTRU Cryptosystems Abstract. We introduce the concept of Modi¯ed Parameter Attacks, a natural extension of the idea of Adapative Chosen Ciphertext Attacks (CCA2) under which some CCA2 secure systems can be shown to be insecure. These insecurities can be addressed at the application level, but can also be addressed when cryptographic schemes are being designed. We survey some existing CCA2 secure systems which are vulnerable to this attack and suggest practical countermeasures. 1 Introduction It is of great interest, when studying cryptosystems, to make statements about their security under certain attack models. The contribution of this paper is to suggest an attack model for public key encryption schemes, stronger than those typically considered at present, within which the se- curity properties of the scheme can be evaluated. We start by identifying existing concepts used in the study of public key encryption schemes. First, we review security properties of indistin- guishability and non-malleability. Each of these properties can be looked on as the ability to resist a particular type of attack. { Indistinguishability: An attacker submits two plaintexts, x0 and x1, to an encryption oracle, which encrypts one of them and outputs the ciphertext y. If the attacker cannot identify, with non-negligible advantage, the plaintext which was used to produce y, the system is said to have the property of indistinguishability. { Non-Malleability: An attacker is given a plaintext x and the corre- sponding ciphertext y. If the attacker can alter y to obtain y0, where y0 decrypts to a message x0 that is related to x in some simple way, then the system is said to be malleable.