GOST R 34.12-2015: Block Cipher "Magma"
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Iso/Iec Jtc 1/Sc 27/Wg 2 N 1804
ISO/IEC JTC 1/SC 27/WG 2 N 1804 ISO/IEC JTC 1/SC 27/WG 2 Cryptography and security mechanisms Convenorship: JISC (Japan) Document type: Officer's Contribution Title: A Memo on Kuznyechik S-Box Status: Date of document: 2018-09-27 Source: Project Editor (Vasily Shishkin), Project Co-editor (Grigory Marshalko) Expected action: ACT Action due date: 2018-10-04 No. of pages: 1 + 4 Email of convenor: [email protected] Committee URL: https://isotc.iso.org/livelink/livelink/open/jtc1sc27wg2 A Memo on Kuznyechik S-Box During ballot on 18033-3 DAmd1 (finished in June 2018) comments from some NB were received concerning issues regarding Kuznyechik design rationale and its parameters origins. The goal of this Memo is to provide all relevant information known to the designers of the algorithm. Kuznyechik has transparent and well studied design. Its design rationale was introduced to WG2 experts in 2016 by presentation (WG2) N1740. Kuznyechik is based on well examined constructions. Each transformation provides certain cryptographic properties. All transformations used as building blocks have transparent origin. The only transformation used in Kuznyechik which origin may be questioned is the S-box π. This S-box was chosen from Streebog hash-function and it was synthesized in 2007. Note that through many years of cryptanalysis no weakness of this S-box was found. The S-box π was obtained by pseudo- random search and the following properties were taken into account. 1. The differential characteristic π pπ = max pα,β; α,β2V8nf0g π where pα,β = Pfπ(x ⊕ α) ⊕ π(x) = βg. -
The Missing Difference Problem, and Its Applications to Counter Mode
The Missing Difference Problem, and its Applications to Counter Mode Encryption? Ga¨etanLeurent and Ferdinand Sibleyras Inria, France fgaetan.leurent,[email protected] Abstract. The counter mode (CTR) is a simple, efficient and widely used encryption mode using a block cipher. It comes with a security proof that guarantees no attacks up to the birthday bound (i.e. as long as the number of encrypted blocks σ satisfies σ 2n=2), and a matching attack that can distinguish plaintext/ciphertext pairs from random using about 2n=2 blocks of data. The main goal of this paper is to study attacks against the counter mode beyond this simple distinguisher. We focus on message recovery attacks, with realistic assumptions about the capabilities of an adversary, and evaluate the full time complexity of the attacks rather than just the query complexity. Our main result is an attack to recover a block of message with complexity O~(2n=2). This shows that the actual security of CTR is similar to that of CBC, where collision attacks are well known to reveal information about the message. To achieve this result, we study a simple algorithmic problem related to the security of the CTR mode: the missing difference problem. We give efficient algorithms for this problem in two practically relevant cases: where the missing difference is known to be in some linear subspace, and when the amount of data is higher than strictly required. As a further application, we show that the second algorithm can also be used to break some polynomial MACs such as GMAC and Poly1305, with a universal forgery attack with complexity O~(22n=3). -
State of the Art in Lightweight Symmetric Cryptography
State of the Art in Lightweight Symmetric Cryptography Alex Biryukov1 and Léo Perrin2 1 SnT, CSC, University of Luxembourg, [email protected] 2 SnT, University of Luxembourg, [email protected] Abstract. Lightweight cryptography has been one of the “hot topics” in symmetric cryptography in the recent years. A huge number of lightweight algorithms have been published, standardized and/or used in commercial products. In this paper, we discuss the different implementation constraints that a “lightweight” algorithm is usually designed to satisfy. We also present an extensive survey of all lightweight symmetric primitives we are aware of. It covers designs from the academic community, from government agencies and proprietary algorithms which were reverse-engineered or leaked. Relevant national (nist...) and international (iso/iec...) standards are listed. We then discuss some trends we identified in the design of lightweight algorithms, namely the designers’ preference for arx-based and bitsliced-S-Box-based designs and simple key schedules. Finally, we argue that lightweight cryptography is too large a field and that it should be split into two related but distinct areas: ultra-lightweight and IoT cryptography. The former deals only with the smallest of devices for which a lower security level may be justified by the very harsh design constraints. The latter corresponds to low-power embedded processors for which the Aes and modern hash function are costly but which have to provide a high level security due to their greater connectivity. Keywords: Lightweight cryptography · Ultra-Lightweight · IoT · Internet of Things · SoK · Survey · Standards · Industry 1 Introduction The Internet of Things (IoT) is one of the foremost buzzwords in computer science and information technology at the time of writing. -
Construction of Stream Ciphers from Block Ciphers and Their Security
Sridevi, International Journal of Computer Science and Mobile Computing, Vol.3 Issue.9, September- 2014, pg. 703-714 Available Online at www.ijcsmc.com International Journal of Computer Science and Mobile Computing A Monthly Journal of Computer Science and Information Technology ISSN 2320–088X IJCSMC, Vol. 3, Issue. 9, September 2014, pg.703 – 714 RESEARCH ARTICLE Construction of Stream Ciphers from Block Ciphers and their Security Sridevi, Assistant Professor, Department of Computer Science, Karnatak University, Dharwad Abstract: With well-established encryption algorithms like DES or AES at hand, one could have the impression that most of the work for building a cryptosystem -for example a suite of algorithms for the transmission of encrypted data over the internet - is already done. But the task of a cipher is very specific: to encrypt or decrypt a data block of a specified length. Given an plaintext of arbitrary length, the most simple approach would be to break it down to blocks of the desired length and to use padding for the final block. Each block is encrypted separately with the same key, which results in identical ciphertext blocks for identical plaintext blocks. This is known as Electronic Code Book (ECB) mode of operation, and is not recommended in many situations because it does not hide data patterns well. Furthermore, ciphertext blocks are independent from each other, allowing an attacker to substitute, delete or replay blocks unnoticed. The feedback modes in fact turn the block cipher into a stream cipher by using the algorithm as a keystream generator. Since every mode may yield different usage and security properties, it is necessary to analyse them in detail. -
Thesis Submitted for the Degree of Doctor of Philosophy
Optimizations in Algebraic and Differential Cryptanalysis Theodosis Mourouzis Department of Computer Science University College London A thesis submitted for the degree of Doctor of Philosophy January 2015 Title of the Thesis: Optimizations in Algebraic and Differential Cryptanalysis Ph.D. student: Theodosis Mourouzis Department of Computer Science University College London Address: Gower Street, London, WC1E 6BT E-mail: [email protected] Supervisors: Nicolas T. Courtois Department of Computer Science University College London Address: Gower Street, London, WC1E 6BT E-mail: [email protected] Committee Members: 1. Reviewer 1: Professor Kenny Paterson 2. Reviewer 2: Dr Christophe Petit Day of the Defense: Signature from head of PhD committee: ii Declaration I herewith declare that I have produced this paper without the prohibited assistance of third parties and without making use of aids other than those specified; notions taken over directly or indirectly from other sources have been identified as such. This paper has not previously been presented in identical or similar form to any other English or foreign examination board. The following thesis work was written by Theodosis Mourouzis under the supervision of Dr Nicolas T. Courtois at University College London. Signature from the author: Abstract In this thesis, we study how to enhance current cryptanalytic techniques, especially in Differential Cryptanalysis (DC) and to some degree in Al- gebraic Cryptanalysis (AC), by considering and solving some underlying optimization problems based on the general structure of the algorithm. In the first part, we study techniques for optimizing arbitrary algebraic computations in the general non-commutative setting with respect to sev- eral metrics [42, 44]. -
Linear-XOR and Additive Checksums Don't Protect Damgård-Merkle
Linear-XOR and Additive Checksums Don’t Protect Damg˚ard-Merkle Hashes from Generic Attacks Praveen Gauravaram1! and John Kelsey2 1 Technical University of Denmark (DTU), Denmark Queensland University of Technology (QUT), Australia. [email protected] 2 National Institute of Standards and Technology (NIST), USA [email protected] Abstract. We consider the security of Damg˚ard-Merkle variants which compute linear-XOR or additive checksums over message blocks, inter- mediate hash values, or both, and process these checksums in computing the final hash value. We show that these Damg˚ard-Merkle variants gain almost no security against generic attacks such as the long-message sec- ond preimage attacks of [10,21] and the herding attack of [9]. 1 Introduction The Damg˚ard-Merkle construction [3, 14] (DM construction in the rest of this article) provides a blueprint for building a cryptographic hash function, given a fixed-length input compression function; this blueprint is followed for nearly all widely-used hash functions. However, the past few years have seen two kinds of surprising results on hash functions, that have led to a flurry of research: 1. Generic attacks apply to the DM construction directly, and make few or no assumptions about the compression function. These attacks involve attacking a t-bit hash function with more than 2t/2 work, in order to violate some property other than collision resistance. Exam- ples of generic attacks are Joux multicollision [8], long-message second preimage attacks [10,21] and herding attack [9]. 2. Cryptanalytic attacks apply to the compression function of the hash function. -
First Modes of Operation Workshop (October 2000)-Key Feedback Mode: a Keystream Generator with Provable Security
Key Feedback Mode: a Keystream Generator with Provable Security Johan H˚astad Royal Inst. of Technology, Sweden Institute for Advanced Study Mats N¨aslund Ericsson Research, Sweden 1 The setup Given A good block cryptosystem (AES). Wanted A good pseudorandom generator. 2 A good pseudorandom generator Short random seed 10010110110101.....01 PRG 001010110101010110001011011101.......01 Long "random-looking" sequence Generates many random looking • bits from a short initial seed. Looks very similar to truly random • bits. Passes many statistical tests. 3 Which statistical tests? Classically A list of good standard tests. Blum-Micali, Yao: All tests that can be implemented efficiently. 4 Passing a statistical test PR Probability the test rejects a truly random string. PG Probability the test rejects a string which is the output of the generator (on a random seed). P P E E-distinguishes. | R − G|≥ ⇔ 5 How good is AES? 1. Hard to crack given only the cryptotext. 2. Hard to find the key given both the plaintext and the cryptotext. 3. Looks like a random permutation when the key is unknown. 6 The easy solution Assume AES ( ) behaves like a K · random permutation. Counter-mode, i.e. outputting AESK(ctr + i);i =0; 1; 2 ::: gives a good pseudorandom generator which is very efficient and (almost by definition) passes all statistical tests. 7 Our proposal Assume that it is hard to find the key given the plaintext and the ciphertext (a diamond in the raw). Cut and polish it to get a good pseudorandom generator. 8 Traditional academic set-up We have a function f which is one-way, i.e. -
CRYPTANALYSIS of GOST in the MULTIPLE-KEY SCENARIO 1. The
Ø Ñ ÅØÑØÐ ÈÙ ÐØÓÒ× DOI: 10.2478/tmmp-2013-0035 Tatra Mt. Math. Publ. 57 (2013), 45–63 CRYPTANALYSIS OF GOST IN THE MULTIPLE-KEY SCENARIO Nicolas T. Courtois ABSTRACT. GOST 28147-89 is a well-known 256-bit block cipher. In 2010 GOST was submitted to ISO, to become an international standard. Then many academic attacks which allow to break full GOST faster than brute force have been found. The fastest known single-key attack on GOST for 264 of data is 2179 of [Courtois, N.: An improved differential attack on full GOST, Cryptol- ogy ePrint Archive, Report 2012/138, http://eprint.iacr.org/2012/138]and for 232 of data it is 2191 of [Courtois, N.: Algebraic complexity reduction and cryptanalysis of GOST, Preprint, 2010–13, http://eprint.iacr.org/2011/626]. Other results are slower but require significantly less memory [Courtois, N.: Al- gebraic complexity reduction and cryptanalysis of GOST, Preprint, 2010–2013, http://eprint.iacr.org/2011/626], [Dinur, I.—Dunkelman, O.—Shamir, A.: Improved attacks on full GOST, in: Fast Software Encryption—FSE ’12, 19th Internat. Workshop, Washington, USA, 2012, Lecture Notes in Comput. Sci., Vol. 7549, Springer, Berlin, 2012, pp. 9–28, http://eprint.iacr.org/2011/558/]. The common stereotype is that these will be “the best” attacks on GOST. However, ciphers are not used in practice with single keys, on the contrary. In this paper we intend to show that there exist attacks on GOST which are more versatile and even somewhat more “practical” than the best single key attack. We argument that multiple random key attacks not single key attacks, are more practical and more likely to be executed in the real life. -
Exponential S-Boxes: a Link Between the S-Boxes of Belt and Kuznyechik/Streebog
Exponential S-Boxes: a Link Between the S-Boxes of BelT and Kuznyechik/Streebog Léo Perrin and Aleksei Udovenko SnT, University of Luxembourg {leo.perrin,aleksei.udovenko}@uni.lu Abstract. The block cipher Kuznyechik and the hash function Streebog were recently standardized by the Russian Federation. These primitives use a common 8-bit S-Box, denoted 휋, which is given only as a look-up table. The rationale behind its design is, for all practical purposes, kept secret by its authors. In a paper presented at Eurocrypt 2016, Biryukov et al. reverse-engineered this S-Box and recovered an unusual Feistel-like structure relying on finite field multiplications. In this paper, we provide a new decomposition of this S-Box and describe how we obtained it. The first step was the analysis of the 8-bit S-Box of the current standard block cipher of Belarus, BelT. This S-Box is a variant of a so-called exponential substitution, a concept we generalize into pseudo-exponential substitution. We derive distinguishers for such permutations based on properties of their linear approximation tables and notice that 휋 shares some of them. We then show that 휋 indeed has a decomposition based on a pseudo-exponential substitution. More precisely, we obtain a simpler structure based on an 8-bit finite field exponentiation, one 4-bit S-Box, a linear layer and a few modular arithmetic operations. We also make several observations which may help cryptanalysts attempting to reverse-engineer other S-Boxes. For example, the visual pattern used in the previous work as a starting point to decompose 휋 is mathematically formalized and the use of differential patterns involving operations other than exclusive-or is explored. -
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). -
Provably Secure Counter Mode with Related Key-Based Internal Re-Keying
Related keys CTRR mode and its security estimation Related-key cryptanalysis of Kuznyechik Provably secure counter mode with related key-based internal re-keying Goncharenko K. Moscow State University, al [email protected], Alekseev E. CryptoPro LLC, Ph.D., [email protected], Marshalko G. Technical committee for standardization (TC26), marshalko [email protected]. May 30,Provably 2018 secure counter mode with related key-based internal re-keying Related keys CTRR mode and its security estimation Related-key cryptanalysis of Kuznyechik It is very important to analyse block ciphers in related-key model! Why? Because situation when a lot of key relations are known can emerge when key generating machine is broken. Or just key generation algorithm is poor (like it was in WEP). Provably secure counter mode with related key-based internal re-keying Related keys CTRR mode and its security estimation Related-key cryptanalysis of Kuznyechik One can consider this motivation to be inconvincing and the problem of related-key analysis to be just an entertaining task. There are much less papers on this topic than on classic methods. As a result we still have no published related-keys analysis on Kuznyechik! Provably secure counter mode with related key-based internal re-keying Related keys CTRR mode and its security estimation Related-key cryptanalysis of Kuznyechik Provably secure counter mode with related key-based internal re-keying I some protocols may use related keys by design to generate key material easier and faster (such a cryptosystem is discussed in our work). Related keys CTRR mode and its security estimation Related-key cryptanalysis of Kuznyechik However the motivation can be adjusted with more real examples, when related keys appear (Razali E., Phan R.C.-W.: On The Existence of Related-Key Oracles in Cryptosystems based on Block Ciphers). -
On Hash Functions Using Checksums
Downloaded from orbit.dtu.dk on: Sep 27, 2021 On hash functions using checksums Gauravaram, Praveen; Kelsey, John; Knudsen, Lars Ramkilde; Thomsen, Søren Steffen Publication date: 2008 Document Version Early version, also known as pre-print Link back to DTU Orbit Citation (APA): Gauravaram, P., Kelsey, J., Knudsen, L. R., & Thomsen, S. S. (2008). On hash functions using checksums. MAT report No. 2008-06 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 You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. On hash functions using checksums ⋆ Praveen Gauravaram1⋆⋆, John Kelsey2, Lars Knudsen1, and Søren Thomsen1⋆ ⋆ ⋆ 1 DTU Mathematics, Technical University of Denmark, Denmark [email protected],[email protected],[email protected] 2 National Institute of Standards and Technology (NIST), USA [email protected] Abstract. We analyse the security of iterated hash functions that compute an input dependent check- sum which is processed as part of the hash computation.