RACE: Randomized Counter Mode of Authenticated Encryption Using Cellular Automata
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The Order of Encryption and Authentication for Protecting Communications (Or: How Secure Is SSL?)?
The Order of Encryption and Authentication for Protecting Communications (Or: How Secure is SSL?)? Hugo Krawczyk?? Abstract. We study the question of how to generically compose sym- metric encryption and authentication when building \secure channels" for the protection of communications over insecure networks. We show that any secure channels protocol designed to work with any combina- tion of secure encryption (against chosen plaintext attacks) and secure MAC must use the encrypt-then-authenticate method. We demonstrate this by showing that the other common methods of composing encryp- tion and authentication, including the authenticate-then-encrypt method used in SSL, are not generically secure. We show an example of an en- cryption function that provides (Shannon's) perfect secrecy but when combined with any MAC function under the authenticate-then-encrypt method yields a totally insecure protocol (for example, ¯nding passwords or credit card numbers transmitted under the protection of such protocol becomes an easy task for an active attacker). The same applies to the encrypt-and-authenticate method used in SSH. On the positive side we show that the authenticate-then-encrypt method is secure if the encryption method in use is either CBC mode (with an underlying secure block cipher) or a stream cipher (that xor the data with a random or pseudorandom pad). Thus, while we show the generic security of SSL to be broken, the current practical implementations of the protocol that use the above modes of encryption are safe. 1 Introduction The most widespread application of cryptography in the Internet these days is for implementing a secure channel between two end points and then exchanging information over that channel. -
Authenticated Key-Exchange: Protocols, Attacks, and Analyses
The HMAC construction: A decade later Ran Canetti IBM Research What is HMAC? ● HMAC: A Message Authentication Code based on Cryptographic Hash functions [Bellare-C-Krawczyk96]. ● Developed for the IPSec standard of the Internet Engineering Task Force (IETF). ● Currently: - incorporated in IPSec, SSL/TLS, SSH, Kerberos, SHTTP, HTTPS, SRTP, MSEC, ... - ANSI and NIST standards - Used daily by all of us. Why is HMAC interesting? ● “Theoretical” security analysis impacts the security of real systems. ● Demonstrates the importance of modelling and abstraction in practical cryptography. ● The recent attacks on hash functions highlight the properties of the HMAC design and analysis. ● Use the HMAC lesson to propose requirements for the next cryptographic hash function. Organization ● Authentication, MACs, Hash-based MACs ● HMAC construction and analysis ● Other uses of HMAC: ● Pseudo-Random Functions ● Extractors ● What properties do we want from a “cryptographic hash function”? Authentication m m' A B The goal: Any tampering with messages should be detected. “If B accepts message m from A then A has sent m to B.” • One of the most basic cryptographic tasks • The basis for any security-conscious interaction over an open network Elements of authentication The structure of typical cryptographic solutions: • Initial entity authentication: The parties perform an initial exchange, bootstrapping from initial trusted information on each other. The result is a secret key that binds the parties to each other. • Message authentication: The parties use the key to authenticate exchanged messages via message authentication codes. Message Authentication Codes m,t m',t' A B t=FK(m) t' =? FK(m') • A and B obtain a common secret key K • A and B agree on a keyed function F • A sends t=FK(m) together with m • B gets (m',t') and accepts m' if t'=FK(m'). -
An Integrated Symmetric Key Cryptographic Method
I.J.Modern Education and Computer Science, 2012, 5, 1-9 Published Online June 2012 in MECS (http://www.mecs-press.org/) DOI: 10.5815/ijmecs.2012.05.01 An Integrated Symmetric Key Cryptographic Method – Amalgamation of TTJSA Algorithm , Advanced Caesar Cipher Algorithm, Bit Rotation and Reversal Method: SJA Algorithm Somdip Dey Department of Computer Science, St. Xavier’s College [Autonomous], Kolkata, India. Email: [email protected] Joyshree Nath A.K. Chaudhuri School of IT, Calcutta University, Kolkata, India. Email: [email protected] Asoke Nath Department of Computer Science, St. Xavier’s College [Autonomous], Kolkata, India. Email: [email protected] Abstract—In this paper the authors present a new In banking system the data must be fully secured. Under integrated symmetric-key cryptographic method, named no circumstances the authentic data should go to hacker. SJA, which is the combination of advanced Caesar Cipher In defense the security of data is much more prominent. method, TTJSA method, Bit wise Rotation and Reversal The leakage of data in defense system can be highly fatal method. The encryption method consists of three basic and can cause too much destruction. Due to this security steps: 1) Encryption Technique using Advanced Caesar issue different cryptographic methods are used by Cipher, 2) Encryption Technique using TTJSA Algorithm, different organizations and government institutions to and 3) Encryption Technique using Bit wise Rotation and protect their data online. But, cryptography hackers are Reversal. TTJSA Algorithm, used in this method, is again always trying to break the cryptographic methods or a combination of generalized modified Vernam Cipher retrieve keys by different means. -
Investigation of Some Cryptographic Properties of the 8X8 S-Boxes Created by Quasigroups
Computer Science Journal of Moldova, vol.28, no.3(84), 2020 Investigation of Some Cryptographic Properties of the 8x8 S-boxes Created by Quasigroups Aleksandra Mileva, Aleksandra Stojanova, Duˇsan Bikov, Yunqing Xu Abstract We investigate several cryptographic properties in 8-bit S- boxes obtained by quasigroups of order 4 and 16 with several different algebraic constructions. Additionally, we offer a new construction of N-bit S-boxes by using different number of two layers – the layer of bijectional quasigroup string transformations, and the layer of modular addition with N-bit constants. The best produced 8-bit S-boxes so far are regular and have algebraic degree 7, nonlinearity 98 (linearity 60), differential uniformity 8, and autocorrelation 88. Additionally we obtained 8-bit S-boxes with nonlinearity 100 (linearity 56), differential uniformity 10, autocorrelation 88, and minimal algebraic degree 6. Relatively small set of performed experiments compared with the extremly large set of possible experiments suggests that these results can be improved in the future. Keywords: 8-bit S-boxes, nonlinearity, differential unifor- mity, autocorrelation. MSC 2010: 20N05, 94A60. 1 Introduction The main building blocks for obtaining confusion in all modern block ciphers are so called substitution boxes, or S-boxes. Usually, they work with much less data (for example, 4 or 8 bits) than the block size, so they need to be highly nonlinear. Two of the most successful attacks against modern block ciphers are linear cryptanalysis (introduced by ©2020 by CSJM; A. Mileva, A. Stojanova, D. Bikov, Y. Xu 346 Investigation of Some Cryptographic Properties of 8x8 S-boxes . -
Hello, and Welcome to This Presentation of the STM32 Hash Processor
Hello, and welcome to this presentation of the STM32 hash processor. 1 Hash peripheral is in charge of efficient computing of message digest. A digest is a fixed-length value computed from an input message. A digest is unique - it is virtually impossible to find two messages with the same digest. The original message cannot be retrieved from its digest. Hash digests and Hash-based Message Authentication Code (HMAC) are widely used in communication since they are used to guarantee the integrity and authentication of a transfer. 2 The hash processor supports widely used hash functions including Message Digest 5 (MD5), Secure Hash Algorithm SHA-1 and the more recent SHA-2 with its 224- and 256- bit digest length versions. A hash can also be generated with a secrete-key to produce a message authentication code (MAC). The processor supports bit, byte and half-word swapping. It supports also automatic padding of input data for block alignment. The processor can be used in conjunction with the DMA for automatic processor feeding. 3 All supported hash functions work on 512-bit blocks of data. The input message is split as many times as needed to feed the hash processor. Subsequent blocks are computed sequentially. MD5 is the less robust function with only a 128-bit digest. The SHA standard has two versions SHA-1 and the more recent SHA-2 with its 224- and 256-bit digest length versions. 4 The hash-based message authentication code (HMAC) is used to authenticate messages and verify their integrity. The HMAC function consists of two nested Hash function with a secrete key that is shared by the sender and the receiver. -
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 . -
Message Authentication Codes
MessageMessage AuthenticationAuthentication CodesCodes Was this message altered? Did he really send this? Raj Jain Washington University in Saint Louis Saint Louis, MO 63130 [email protected] Audio/Video recordings of this lecture are available at: http://www.cse.wustl.edu/~jain/cse571-11/ Washington University in St. Louis CSE571S ©2011 Raj Jain 12-1 OverviewOverview 1. Message Authentication 2. MACS based on Hash Functions: HMAC 3. MACs based on Block Ciphers: DAA and CMAC 4. Authenticated Encryption: CCM and GCM 5. Pseudorandom Number Generation Using Hash Functions and MACs These slides are based partly on Lawrie Brown’s slides supplied with William Stallings’s book “Cryptography and Network Security: Principles and Practice,” 5th Ed, 2011. Washington University in St. Louis CSE571S ©2011 Raj Jain 12-2 MessageMessage SecuritySecurity RequirementsRequirements Disclosure Traffic analysis Masquerade Content modification Sequence modification Timing modification Source repudiation Destination repudiation Message Authentication = Integrity + Source Authentication Washington University in St. Louis CSE571S ©2011 Raj Jain 12-3 PublicPublic--KeyKey AuthenticationAuthentication andand SecrecySecrecy A B’s Public A’s PrivateMessage B A Key Key B Double public key encryption provides authentication and integrity. Double public key Very compute intensive Crypto checksum (MAC) is better. Based on a secret key and the message. Can also encrypt with the same or different key. Washington University in St. Louis CSE571S ©2011 Raj Jain 12-4 MACMAC PropertiesProperties A MAC is a cryptographic checksum MAC = CK(M) Condenses a variable-length message M using a secret key To a fixed-sized authenticator Is a many-to-one function Potentially many messages have same MAC But finding these needs to be very difficult Properties: 1. -
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. -
Impossible Differential Cryptanalysis of the Lightweight Block Ciphers TEA, XTEA and HIGHT
Impossible Differential Cryptanalysis of the Lightweight Block Ciphers TEA, XTEA and HIGHT Jiazhe Chen1;2;3?, Meiqin Wang1;2;3??, and Bart Preneel2;3 1 Key Laboratory of Cryptologic Technology and Information Security, Ministry of Education, School of Mathematics, Shandong University, Jinan 250100, China 2 Department of Electrical Engineering ESAT/SCD-COSIC, Katholieke Universiteit Leuven, Kasteelpark Arenberg 10, B-3001 Heverlee, Belgium 3 Interdisciplinary Institute for BroadBand Technology (IBBT), Belgium [email protected] Abstract. TEA, XTEA and HIGHT are lightweight block ciphers with 64-bit block sizes and 128-bit keys. The round functions of the three ci- phers are based on the simple operations XOR, modular addition and shift/rotation. TEA and XTEA are Feistel ciphers with 64 rounds de- signed by Needham and Wheeler, where XTEA is a successor of TEA, which was proposed by the same authors as an enhanced version of TEA. HIGHT, which is designed by Hong et al., is a generalized Feistel cipher with 32 rounds. These block ciphers are simple and easy to implement but their diffusion is slow, which allows us to find some impossible prop- erties. This paper proposes a method to identify the impossible differentials for TEA and XTEA by using the weak diffusion, where the impossible differential comes from a bit contradiction. Our method finds a 14-round impossible differential of XTEA and a 13-round impossible differential of TEA, which result in impossible differential attacks on 23-round XTEA and 17-round TEA, respectively. These attacks significantly improve the previous impossible differential attacks on 14-round XTEA and 11-round TEA given by Moon et al. -
New Cryptanalysis of Block Ciphers with Low Algebraic Degree
New Cryptanalysis of Block Ciphers with Low Algebraic Degree Bing Sun1,LongjiangQu1,andChaoLi1,2 1 Department of Mathematics and System Science, Science College of National University of Defense Technology, Changsha, China, 410073 2 State Key Laboratory of Information Security, Graduate University of Chinese Academy of Sciences, China, 10039 happy [email protected], ljqu [email protected] Abstract. Improved interpolation attack and new integral attack are proposed in this paper, and they can be applied to block ciphers using round functions with low algebraic degree. In the new attacks, we can determine not only the degree of the polynomial, but also coefficients of some special terms. Thus instead of guessing the round keys one by one, we can get the round keys by solving some algebraic equations over finite field. The new methods are applied to PURE block cipher successfully. The improved interpolation attacks can recover the first round key of 8-round PURE in less than a second; r-round PURE with r ≤ 21 is breakable with about 3r−2 chosen plaintexts and the time complexity is 3r−2 encryptions; 22-round PURE is breakable with both data and time complexities being about 3 × 320. The new integral attacks can break PURE with rounds up to 21 with 232 encryptions and 22-round with 3 × 232 encryptions. This means that PURE with up to 22 rounds is breakable on a personal computer. Keywords: block cipher, Feistel cipher, interpolation attack, integral attack. 1 Introduction For some ciphers, the round function can be described either by a low degree polynomial or by a quotient of two low degree polynomials over finite field with characteristic 2. -
Stronger Security Variants of GCM-SIV
Stronger Security Variants of GCM-SIV Tetsu Iwata1 and Kazuhiko Minematsu2 1 Nagoya University, Nagoya, Japan, [email protected] 2 NEC Corporation, Kawasaki, Japan, [email protected] Abstract. At CCS 2015, Gueron and Lindell proposed GCM-SIV, a provably secure authenticated encryption scheme that remains secure even if the nonce is repeated. While this is an advantage over the original GCM, we first point out that GCM-SIV allows a trivial distinguishing attack with about 248 queries, where each query has one plaintext block. This shows the tightness of the security claim and does not contradict the provable security result. However, the original GCM resists the attack, and this poses a question of designing a variant of GCM-SIV that is secure against the attack. We present a minor variant of GCM-SIV, which we call GCM-SIV1, and discuss that GCM-SIV1 resists the attack, and it offers a security trade-off compared to GCM-SIV. As the main contribution of the paper, we explore a scheme with a stronger security bound. We present GCM-SIV2 which is obtained by running two instances of GCM-SIV1 in parallel and mixing them in a simple way. We show that it is secure up to 285.3 query complexity, where the query complexity is measured in terms of the total number of blocks of the queries. Finally, we generalize this to show GCM-SIVr by running r instances of GCM-SIV1 in parallel, where r ≥ 3, and show that the scheme is secure up to 2128r/(r+1) query complexity. -
FIPS 198, the Keyed-Hash Message Authentication Code (HMAC)
ARCHIVED PUBLICATION The attached publication, FIPS Publication 198 (dated March 6, 2002), was superseded on July 29, 2008 and is provided here only for historical purposes. For the most current revision of this publication, see: http://csrc.nist.gov/publications/PubsFIPS.html#198-1. FIPS PUB 198 FEDERAL INFORMATION PROCESSING STANDARDS PUBLICATION The Keyed-Hash Message Authentication Code (HMAC) CATEGORY: COMPUTER SECURITY SUBCATEGORY: CRYPTOGRAPHY Information Technology Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899-8900 Issued March 6, 2002 U.S. Department of Commerce Donald L. Evans, Secretary Technology Administration Philip J. Bond, Under Secretary National Institute of Standards and Technology Arden L. Bement, Jr., Director Foreword The Federal Information Processing Standards Publication Series of the National Institute of Standards and Technology (NIST) is the official series of publications relating to standards and guidelines adopted and promulgated under the provisions of Section 5131 of the Information Technology Management Reform Act of 1996 (Public Law 104-106) and the Computer Security Act of 1987 (Public Law 100-235). These mandates have given the Secretary of Commerce and NIST important responsibilities for improving the utilization and management of computer and related telecommunications systems in the Federal government. The NIST, through its Information Technology Laboratory, provides leadership, technical guidance, and coordination of government efforts in the development of standards and guidelines in these areas. Comments concerning Federal Information Processing Standards Publications are welcomed and should be addressed to the Director, Information Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8900, Gaithersburg, MD 20899-8900. William Mehuron, Director Information Technology Laboratory Abstract This standard describes a keyed-hash message authentication code (HMAC), a mechanism for message authentication using cryptographic hash functions.