Encrypted Key Exchange: Password-Based Protocols Secure Against Dictionary Attacks
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Authentication in Key-Exchange: Definitions, Relations and Composition
Authentication in Key-Exchange: Definitions, Relations and Composition Cyprien Delpech de Saint Guilhem1;2, Marc Fischlin3, and Bogdan Warinschi2 1 imec-COSIC, KU Leuven, Belgium 2 Dept Computer Science, University of Bristol, United Kingdom 3 Computer Science, Technische Universit¨atDarmstadt, Germany [email protected], [email protected], [email protected] Abstract. We present a systematic approach to define and study authentication notions in authenti- cated key-exchange protocols. We propose and use a flexible and expressive predicate-based definitional framework. Our definitions capture key and entity authentication, in both implicit and explicit vari- ants, as well as key and entity confirmation, for authenticated key-exchange protocols. In particular, we capture critical notions in the authentication space such as key-compromise impersonation resis- tance and security against unknown key-share attacks. We first discuss these definitions within the Bellare{Rogaway model and then extend them to Canetti{Krawczyk-style models. We then show two useful applications of our framework. First, we look at the authentication guarantees of three representative protocols to draw several useful lessons for protocol design. The core technical contribution of this paper is then to formally establish that composition of secure implicitly authenti- cated key-exchange with subsequent confirmation protocols yields explicit authentication guarantees. Without a formal separation of implicit and explicit authentication from secrecy, a proof of this folklore result could not have been established. 1 Introduction The commonly expected level of security for authenticated key-exchange (AKE) protocols comprises two aspects. Authentication provides guarantees on the identities of the parties involved in the protocol execution. -
The Twin Diffie-Hellman Problem and Applications
The Twin Diffie-Hellman Problem and Applications David Cash1 Eike Kiltz2 Victor Shoup3 February 10, 2009 Abstract We propose a new computational problem called the twin Diffie-Hellman problem. This problem is closely related to the usual (computational) Diffie-Hellman problem and can be used in many of the same cryptographic constructions that are based on the Diffie-Hellman problem. Moreover, the twin Diffie-Hellman problem is at least as hard as the ordinary Diffie-Hellman problem. However, we are able to show that the twin Diffie-Hellman problem remains hard, even in the presence of a decision oracle that recognizes solutions to the problem — this is a feature not enjoyed by the Diffie-Hellman problem in general. Specifically, we show how to build a certain “trapdoor test” that allows us to effectively answer decision oracle queries for the twin Diffie-Hellman problem without knowing any of the corresponding discrete logarithms. Our new techniques have many applications. As one such application, we present a new variant of ElGamal encryption with very short ciphertexts, and with a very simple and tight security proof, in the random oracle model, under the assumption that the ordinary Diffie-Hellman problem is hard. We present several other applications as well, including: a new variant of Diffie and Hellman’s non-interactive key exchange protocol; a new variant of Cramer-Shoup encryption, with a very simple proof in the standard model; a new variant of Boneh-Franklin identity-based encryption, with very short ciphertexts; a more robust version of a password-authenticated key exchange protocol of Abdalla and Pointcheval. -
2.4 the Random Oracle Model
國 立 交 通 大 學 資訊工程學系 博 士 論 文 可證明安全的公開金鑰密碼系統與通行碼驗證金鑰 交換 Provably Secure Public Key Cryptosystems and Password Authenticated Key Exchange Protocols 研 究 生:張庭毅 指導教授:楊維邦 教授 黃明祥 教授 中 華 民 國 九 十 五 年 十 二 月 可證明安全的公開金鑰密碼系統與通行碼驗證金鑰交換 Provably Secure Public Key Cryptosystems and Password Authenticated Key Exchange Protocols 研 究 生:張庭毅 Student:Ting-Yi Chang 指導教授:楊維邦 博士 Advisor:Dr. Wei-Pang Yang 黃明祥 博士 Dr. Min-Shiang Hwang 國 立 交 通 大 學 資 訊 工 程 學 系 博 士 論 文 A Dissertation Submitted to Department of Computer Science College of Computer Science National Chiao Tung University in partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Computer Science December 2006 Hsinchu, Taiwan, Republic of China 中華民國九十五年十二月 ¡¢£¤¥¦§¨© ª« ¬ Æ ¯ « ¡¨ © ¡¢£¤¥ ¦§¨©¢ª«¬ Æ ¯ Æ Æ Æ ¡ ElGamal ¦§ °±¥ ²³´ ·§±¥¸¹º»¼½¶¾¿§¾¿¸¹³ °µ¶ p ° p§¾¿ ElGamal Hwang §°À¡Á²±¥·§ÂÃÄŨ© ElGamal-like È ÆÇ§È¤ÉÀÊËÌ¡ÍÎϧElGamal-like IND-CPA ¡¦ÃÅ Á²±¥·ÁÃÄŧ¨©§Æ ° ½¡ÐÑÒµ§ IND-CPA ElGamal IND- ±È¤±¥ÓÔÕ§ CCA2§ ElGamal-extended ¡Öר¬Ù¶ÚÀÛܰ§¨©ÝÞ°ÛÜß§ ¡¦§ËÌ IND-CPAPAIR ElGamal-extended Ô°°ÃÄÅ ¬§DZàáâ ãäåæçèé°¡êÛܰëìíîï§åÉ i ïíîÛܰ먩ǰ § ðñòóô ¨©õö÷°§Àäå øùרú§ûüÀÆý°þÿì° ÛÜµÌ °Ûܱ¡ Bellare-Pointcheval-Rogaway ¯À°úÐÑÒ·§¨© ° Diffie-Hellman õ°Ý§¡¦§ ò°¥§§±¥§Diffie- Hellman ¯§¥§§Èç§§ Èç§§ô§§ç±Ûܧ §ÐÑÒ ii Provably Secure Public Key Cryptosystems and Password Authenticated Key Exchange Protocols Student: Ting-Yi Chang Advisor: Dr. Wei-Pang Yang Dr. Min-Shiang Hwang Institute of Computer Science and Engineering National Chiao Tung University ABSTRACT In this thesis, we focus on two topics: public key cryptosystems and pass- word authenticated key exchange protocols. -
2.3 Diffie–Hellman Key Exchange
2.3. Di±e{Hellman key exchange 65 q q q q q q 6 q qq q q q q q q 900 q q q q q q q qq q q q q q q q q q q q q q q q q 800 q q q qq q q q q q q q q q qq q q q q q q q q q q q 700 q q q q q q q q q q q q q q q q q q q q q q q q q q qq q 600 q q q q q q q q q q q q qq q q q q q q q q q q q q q q q q q qq q q q q q q q q 500 q qq q q q q q qq q q q q q qqq q q q q q q q q q q q q q qq q q q 400 q q q q q q q q q q q q q q q q q q q q q q q q q 300 q q q q q q q q q q q q q q q q q q qqqq qqq q q q q q q q q q q q 200 q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q qq q q qq q q 100 q q q q q q q q q q q q q q q q q q q q q q q q q 0 q - 0 30 60 90 120 150 180 210 240 270 Figure 2.2: Powers 627i mod 941 for i = 1; 2; 3;::: any group and use the group law instead of multiplication. -
Elliptic Curves in Public Key Cryptography: the Diffie Hellman
Elliptic Curves in Public Key Cryptography: The Diffie Hellman Key Exchange Protocol and its relationship to the Elliptic Curve Discrete Logarithm Problem Public Key Cryptography Public key cryptography is a modern form of cryptography that allows different parties to exchange information securely over an insecure network, without having first to agree upon some secret key. The main use of public key cryptography is to provide information security in computer science, for example to transfer securely email, credit card details or other secret information between sender and recipient via the internet. There are three steps involved in transferring information securely from person A to person B over an insecure network. These are encryption of the original information, called the plaintext, transfer of the encrypted message, or ciphertext, and decryption of the ciphertext back into plaintext. Since the transfer of the ciphertext is over an insecure network, any spy has access to the ciphertext and thus potentially has access to the original information, provided he is able to decipher the message. Thus, a successful cryptosystem must be able encrypt the original message in such a way that only the intended receiver can decipher the ciphertext. The goal of public key cryptography is to make the problem of deciphering the encrypted message too difficult to do in a reasonable time (by say brute-force) unless certain key facts are known. Ideally, only the intended sender and receiver of a message should know these certain key facts. Any certain piece of information that is essential in order to decrypt a message is known as a key. -
Multi-Server Authentication Key Exchange Approach in Bigdata Environment
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 04 Issue: 07 | July -2017 www.irjet.net p-ISSN: 2395-0072 MULTI-SERVER AUTHENTICATION KEY EXCHANGE APPROACH IN BIGDATA ENVIRONMENT Miss. Kiran More1, Prof. Jyoti Raghatwan2 1Kiran More, PG Student. Dept. of Computer Engg. RMD Sinhgad school of Engineering Warje, Pune 2Prof. Jyoti Raghatwan, Dept. of Computer Engg. RMD Sinhgad school of Engineering Warje, Pune ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - The key establishment difficulty is the maximum Over-all Equivalent Files System. Which are usually required central issue and we learn the trouble of key organization for for advanced scientific or data exhaustive applications such secure many to many communications for past several years. as digital animation studios, computational fluid dynamics, The trouble is stimulated by the broadcast of huge level and semiconductor manufacturing. detached file organizations behind similar admission to In these milieus, hundreds or thousands of file various storage space tactics. Our chore focal ideas on the structure clients bit data and engender very much high current Internet commonplace for such folder systems that is summative I/O load on the file coordination supporting Parallel Network Folder System [pNFS], which generates petabytes or terabytes scale storage capacities. Liberated of employment of Kerberos to establish up similar session keys the enlargement of the knot and high-performance flanked by customers and storing strategy. Our evaluation of computing, the arrival of clouds and the MapReduce the available Kerberos bottommost procedure validates that it program writing model has resulted in file system such as has a numeral of borders: (a) a metadata attendant make the Hadoop Distributed File System (HDFS). -
Authentication and Key Distribution in Computer Networks and Distributed Systems
13 Authentication and key distribution in computer networks and distributed systems Rolf Oppliger University of Berne Institute for Computer Science and Applied Mathematics {JAM) Neubruckstrasse 10, CH-3012 Bern Phone +41 31 631 89 51, Fax +41 31 631 39 65, [email protected] Abstract Authentication and key distribution systems are used in computer networks and dis tributed systems to provide security services at the application layer. There are several authentication and key distribution systems currently available, and this paper focuses on Kerberos (OSF DCE), NetSP, SPX, TESS and SESAME. The systems are outlined and reviewed with special regard to the security services they offer, the cryptographic techniques they use, their conformance to international standards, and their availability and exportability. Keywords Authentication, key distribution, Kerberos, NetSP, SPX, TESS, SESAME 1 INTRODUCTION Authentication and key distribution systems are used in computer networks and dis tributed systems to provide security services at the application layer. There are several authentication and key distribution systems currently available, and this paper focuses on Kerberos (OSF DCE), NetSP, SPX, TESS and SESAME. The systems are outlined and reviewed with special regard to the security services they offer, the cryptographic techniques they use, their conformance to international standards, and their availability and exportability. It is assumed that the reader of this paper is familiar with the funda mentals of cryptography, and the use of cryptographic techniques in computer networks and distributed systems (Oppliger, 1992 and Schneier, 1994). The following notation is used in this paper: • Capital letters are used to refer to principals (users, clients and servers). -
Strong Password-Based Authentication in TLS Using the Three-Party Group Diffie–Hellman Protocol
284 Int. J. Security and Networks, Vol. 2, Nos. 3/4, 2007 Strong password-based authentication in TLS using the three-party group Diffie–Hellman protocol Michel Abdalla* École normale supérieure – CNRS, LIENS, Paris, France E-mail: [email protected] *Corresponding author Emmanuel Bresson Department of Cryptology, CELAR Technology Center, Bruz, France E-mail: [email protected] Olivier Chevassut Lawrence Berkeley National Laboratory, Berkeley, CA, USA E-mail: [email protected] Bodo Möller Horst Görtz Institute for IT Security, Ruhr-Universität Bochum, Bochum, Germany E-mail: [email protected] David Pointcheval École normale supérieure – CNRS, LIENS, Paris, France E-mail: [email protected] Abstract: The internet has evolved into a very hostile ecosystem where ‘phishing’ attacks are common practice. This paper shows that the three-party group Diffie-Hellman key exchange can help protect against these attacks. We have developed password-based ciphersuites for the Transport Layer Security (TLS) protocol that are not only provably secure but also believed to be free from patent and licensing restrictions based on an analysis of relevant patents in the area. Keywords: password authentication; group Diffie–Hellman key exchange; transport layer security; TLS. Reference to this paper should be made as follows: Abdalla, M., Bresson, E., Chevassut, O., Möller, B. and Pointcheval, D. (2007) ‘Strong password-based authentication in TLS using the three-party group Diffie-Hellman protocol’, Int. J. Security and Networks, Vol. 2, Nos. 3/4, pp.284–296. Biographical notes: Michel Abdalla is currently a Researcher with the Centre National de la Recherche Scientifique (CNRS), France and a Member of the Cryptography Team at the Ecole Normale Supérieure (ENS), France. -
Topic 3: One-Time Pad and Perfect Secrecy
Cryptography CS 555 Topic 3: One-time Pad and Perfect Secrecy CS555 Spring 2012/Topic 3 1 Outline and Readings • Outline • One-time pad • Perfect secrecy • Limitation of perfect secrecy • Usages of one-time pad • Readings: • Katz and Lindell: Chapter 2 CS555 Spring 2012/Topic 3 2 One-Time Pad • Fix the vulnerability of the Vigenere cipher by using very long keys • Key is a random string that is at least as long as the plaintext • Encryption is similar to shift cipher • Invented by Vernam in the 1920s CS555 Spring 2012/Topic 3 3 One-Time Pad Let Zm ={0,1,…,m-1} be the alphabet. Plaintext space = Ciphtertext space = Key space = n (Zm) The key is chosen uniformly randomly Plaintext X = (x1 x2 … xn) Key K = (k1 k2 … kn) Ciphertext Y = (y1 y2 … yn) ek(X) = (x1+k1 x2+k2 … xn+kn) mod m dk(Y) = (y1-k1 y2-k2 … yn-kn) mod m CS555 Spring 2012/Topic 3 4 The Binary Version of One-Time Pad Plaintext space = Ciphtertext space = Keyspace = {0,1}n Key is chosen randomly For example: • Plaintext is 11011011 • Key is 01101001 • Then ciphertext is 10110010 CS555 Spring 2012/Topic 3 5 Bit Operators • Bit AND 0 0 = 0 0 1 = 0 1 0 = 0 1 1 = 1 • Bit OR 0 0 = 0 0 1 = 1 1 0 = 1 1 1 = 1 • Addition mod 2 (also known as Bit XOR) 0 0 = 0 0 1 = 1 1 0 = 1 1 1 = 0 • Can we use operators other than Bit XOR for binary version of One-Time Pad? CS555 Spring 2012/Topic 3 6 How Good is One-Time Pad? • Intuitively, it is secure … – The key is random, so the ciphertext is completely random • How to formalize the confidentiality requirement? – Want to say “certain thing” is not learnable by the adversary (who sees the ciphertext). -
Study on the Use of Cryptographic Techniques in Europe
Study on the use of cryptographic techniques in Europe [Deliverable – 2011-12-19] Updated on 2012-04-20 II Study on the use of cryptographic techniques in Europe Contributors to this report Authors: Edward Hamilton and Mischa Kriens of Analysys Mason Ltd Rodica Tirtea of ENISA Supervisor of the project: Rodica Tirtea of ENISA ENISA staff involved in the project: Demosthenes Ikonomou, Stefan Schiffner Agreements or Acknowledgements ENISA would like to thank the contributors and reviewers of this study. Study on the use of cryptographic techniques in Europe III About ENISA The European Network and Information Security Agency (ENISA) is a centre of network and information security expertise for the EU, its member states, the private sector and Europe’s citizens. ENISA works with these groups to develop advice and recommendations on good practice in information security. It assists EU member states in implementing relevant EU leg- islation and works to improve the resilience of Europe’s critical information infrastructure and networks. ENISA seeks to enhance existing expertise in EU member states by supporting the development of cross-border communities committed to improving network and information security throughout the EU. More information about ENISA and its work can be found at www.enisa.europa.eu. Contact details For contacting ENISA or for general enquiries on cryptography, please use the following de- tails: E-mail: [email protected] Internet: http://www.enisa.europa.eu Legal notice Notice must be taken that this publication represents the views and interpretations of the au- thors and editors, unless stated otherwise. This publication should not be construed to be a legal action of ENISA or the ENISA bodies unless adopted pursuant to the ENISA Regulation (EC) No 460/2004 as lastly amended by Regulation (EU) No 580/2011. -
Applications of SKREM-Like Symmetric Key Ciphers
Applications of SKREM-like symmetric key ciphers Mircea-Adrian Digulescu1;2 February 2021 1Individual Researcher, Worldwide 2Formerly: Department of Computer Science, Faculty of Mathematics and Computer Science, University of Bucharest, Romania [email protected], [email protected], [email protected] Abstract In a prior paper we introduced a new symmetric key encryption scheme called Short Key Random Encryption Machine (SKREM), for which we claimed excellent security guarantees. In this paper we present and briey discuss some of its applications outside conventional data encryption. These are Secure Coin Flipping, Cryptographic Hashing, Zero-Leaked-Knowledge Authentication and Autho- rization and a Digital Signature scheme which can be employed on a block-chain. We also briey recap SKREM-like ciphers and the assumptions on which their security are based. The above appli- cations are novel because they do not involve public key cryptography. Furthermore, the security of SKREM-like ciphers is not based on hardness of some algebraic operations, thus not opening them up to specic quantum computing attacks. Keywords: Symmetric Key Encryption, Provable Security, One Time Pad, Zero Knowledge, Cryptographic Commit Protocol, Secure Coin Flipping, Authentication, Authorization, Cryptographic Hash, Digital Signature, Chaos Machine 1 Introduction So far, most encryption schemes able to serve Secure Coin Flipping, Zero-Knowledge Authentication and Digital Signatures, have relied on public key cryptography, which in turn relies on the hardness of prime factorization or some algebraic operation in general. Prime Factorization, in turn, has been shown to be vulnerable to attacks by a quantum computer (see [1]). In [2] we introduced a novel symmetric key encryption scheme, which does not rely on hardness of algebraic operations for its security guarantees. -
NIST SP 800-56: Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography (Superseded)
ARCHIVED PUBLICATION The attached publication, NIST Special Publication 800-56 (dated July 2005), has been superseded and is provided here only for historical purposes. For the most current revision of this publication, see: http://csrc.nist.gov/publications/PubsSPs.html#800-56A. NIST Special Publication 800-56 Recommendation for Pair-Wise July 2005 Key Establishment Schemes Using Discrete Logarithm Cryptography Elaine Barker, Don Johnson, and Miles Smid C O M P U T E R S E C U R I T Y NIST SP 800-56: Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography DRAFT July 2005 DRAFT Abstract This Recommendation specifies key establishment schemes using discrete logarithm cryptography, based on standards developed by the Accredited Standards Committee (ASC) X9, Inc.: ANS X9.42 (Agreement of Symmetric Keys Using Discrete Logarithm Cryptography) and ANS X9.63 (Key Agreement and Key Transport Using Elliptic Curve Cryptography). Worked examples are provided in Appendix D. KEY WORDS: assurances; Diffie-Hellman; elliptic curve cryptography; finite field cryptography; key agreement; key confirmation; key derivation; key establishment; key management; MQV. 2 NIST SP 800-56: Recommendation for Pair-Wise Key Establishment Schemes Using Discrete Logarithm Cryptography DRAFT July 2005 DRAFT Acknowledgements The National Institute of Standards and Technology (NIST) gratefully acknowledges and appreciates contributions by Rich Davis, Mike Hopper and Laurie Law from the National Security Agency concerning the many security