Anonymity and One-Way Authentication in Key Exchange Protocols
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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. -
Fast Elliptic Curve Cryptography in Openssl
Fast Elliptic Curve Cryptography in OpenSSL Emilia K¨asper1;2 1 Google 2 Katholieke Universiteit Leuven, ESAT/COSIC [email protected] Abstract. We present a 64-bit optimized implementation of the NIST and SECG-standardized elliptic curve P-224. Our implementation is fully integrated into OpenSSL 1.0.1: full TLS handshakes using a 1024-bit RSA certificate and ephemeral Elliptic Curve Diffie-Hellman key ex- change over P-224 now run at twice the speed of standard OpenSSL, while atomic elliptic curve operations are up to 4 times faster. In ad- dition, our implementation is immune to timing attacks|most notably, we show how to do small table look-ups in a cache-timing resistant way, allowing us to use precomputation. To put our results in context, we also discuss the various security-performance trade-offs available to TLS applications. Keywords: elliptic curve cryptography, OpenSSL, side-channel attacks, fast implementations 1 Introduction 1.1 Introduction to TLS Transport Layer Security (TLS), the successor to Secure Socket Layer (SSL), is a protocol for securing network communications. In its most common use, it is the \S" (standing for \Secure") in HTTPS. Two of the most popular open- source cryptographic libraries implementing SSL and TLS are OpenSSL [19] and Mozilla Network Security Services (NSS) [17]: OpenSSL is found in, e.g., the Apache-SSL secure web server, while NSS is used by Mozilla Firefox and Chrome web browsers, amongst others. TLS provides authentication between connecting parties, as well as encryp- tion of all transmitted content. Thus, before any application data is transmit- ted, peers perform authentication and key exchange in a TLS handshake. -
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. -
Fast and Secure Generating and Exchanging a Symmetric Key for TVWS Protocol
International Journal of Computer Science and Telecommunications [Volume 9, Issue 3, May 2018] 15 Fast and Secure Generating and Exchanging a Symmetric Key for TVWS Protocol ISSN 2047-3338 Mubark M. A. Elmubark Department of MIS Blue Nile University, Sudan [email protected] Abstract– In network security, symmetric key encryption security key. So many security protocols can be used in methods are commonly used in order to generate and exchange TVWS with pros and cons. a secret key between the sender and the receiver. The main This paper concentrated on security issues in spectrum drawbacks of this method are that, the attackers might access database access and studies these protocols and proposed new the transmitted data and use it to obtain the key and even methods for key generation and exchange. generate new keys. Also, the process of generating the key is inefficient and time consuming. In this paper a new key PKMv1: WiMAX security, as specified by IEEE 802.16 generation and exchange protocol is proposed to overcome the standard [2] is provided by a security sublayer resided in the aforementioned problems in the conventional symmetric key MAC layer. A protocol called PKM has been adopted in the encryption methods. In the proposed protocol, the results show security sublayer of WiMAX to provide authorization, that the protocol is saved. authentication and keys exchange and distribution between Index Terms– Security, Key Generation and Key Exchange Base Stations (BSs) and Subscriber Stations (SSs). The standard has approved two versions of PKM protocol. PKMv1 which is approved in IEEE 802.16-2004 standards I. -
Dynamic Public Key Certificates with Forward Secrecy
electronics Article Dynamic Public Key Certificates with Forward Secrecy Hung-Yu Chien Department of Information Management, National Chi Nan University, Nantou 54561, Taiwan; [email protected] Abstract: Conventionally, public key certificates bind one subject with one static public key so that the subject can facilitate the services of the public key infrastructure (PKI). In PKI, certificates need to be renewed (or revoked) for several practical reasons, including certificate expiration, private key breaches, condition changes, and possible risk reduction. The certificate renewal process is very costly, especially for those environments where online authorities are not available or the connection is not reliable. A dynamic public key certificate (DPKC) facilitates the dynamic changeover of the current public–private key pairs without renewing the certificate authority (CA). This paper extends the previous study in several aspects: (1) we formally define the DPKC; (2) we formally define the security properties; (3) we propose another implementation of the Krawczyk–Rabin chameleon-hash- based DPKC; (4) we propose two variants of DPKC, using the Ateniese–Medeiros key-exposure-free chameleon hash; (5) we detail two application scenarios. Keywords: dynamic public key certificate; chameleon signature; certificate renewal; wireless sensor networks; perfect forward secrecy 1. Introduction Citation: Chien, H.-Y. Dynamic Certificates act as the critical tokens in conventional PKI systems. With the trust Public Key Certificates with Forward of the CA, a -
Ten Strategies of a World-Class Cybersecurity Operations Center Conveys MITRE’S Expertise on Accumulated Expertise on Enterprise-Grade Computer Network Defense
Bleed rule--remove from file Bleed rule--remove from file MITRE’s accumulated Ten Strategies of a World-Class Cybersecurity Operations Center conveys MITRE’s expertise on accumulated expertise on enterprise-grade computer network defense. It covers ten key qualities enterprise- grade of leading Cybersecurity Operations Centers (CSOCs), ranging from their structure and organization, computer MITRE network to processes that best enable effective and efficient operations, to approaches that extract maximum defense Ten Strategies of a World-Class value from CSOC technology investments. This book offers perspective and context for key decision Cybersecurity Operations Center points in structuring a CSOC and shows how to: • Find the right size and structure for the CSOC team Cybersecurity Operations Center a World-Class of Strategies Ten The MITRE Corporation is • Achieve effective placement within a larger organization that a not-for-profit organization enables CSOC operations that operates federally funded • Attract, retain, and grow the right staff and skills research and development • Prepare the CSOC team, technologies, and processes for agile, centers (FFRDCs). FFRDCs threat-based response are unique organizations that • Architect for large-scale data collection and analysis with a assist the U.S. government with limited budget scientific research and analysis, • Prioritize sensor placement and data feed choices across development and acquisition, enteprise systems, enclaves, networks, and perimeters and systems engineering and integration. We’re proud to have If you manage, work in, or are standing up a CSOC, this book is for you. served the public interest for It is also available on MITRE’s website, www.mitre.org. more than 50 years. -
SSL Checklist for Pentesters
SSL Checklist for Pentesters Jerome Smith BSides MCR, 27th June 2014 # whoami whoami jerome • Pentester • Author/trainer – Hands-on technical – Web application, infrastructure, wireless security • Security projects – Log correlation – Dirty data – Incident response exercises • Sysadmin • MSc Computing Science (Dist) • www.exploresecurity.com | @exploresecurity Introduction • Broad review of SSL/TLS checks – Viewpoint of pentester – Pitfalls – Manually replicating what tools do (unless you told the client that SSL Labs would be testing them ) – Issues to consider reporting (but views are my own) • While SSL issues are generally low in priority, it’s nice to get them right! • I’m not a cryptographer: this is all best efforts SSLv2 • Flawed, e.g. no handshake protection → MITM downgrade • Modern browsers do not support SSLv2 anyway – Except for IE but it’s disabled by default from IE7 – That mitigates the risk these days – http://en.wikipedia.org/wiki/Transport_Layer_Security#W eb_browsers • OpenSSL 1.0.0+ doesn’t support it – Which means SSLscan won’t find it – General point: tools that dynamically link to an underlying SSL library in the OS can be limited by what that library supports SSLv2 • Same scan on different OpenSSL versions: SSLv2 • testssl.sh warns you – It can work with any installed OpenSSL version • OpenSSL <1.0.0 s_client -ssl2 switch – More on this later • Recompile OpenSSL – http://blog.opensecurityresearch.com/2013/05/fixing-sslv2-support- in-kali-linux.html • SSLyze 0.7+ is statically linked – Watch out for bug https://github.com/iSECPartners/sslyze/issues/73 -
Sicherheit in Kommunikationsnetzen (Network Security)
Sicherheit in Kommunikationsnetzen (Network Security) Transport Layer Security Dr.-Ing. Matthäus Wander Universität Duisburg-Essen Transport Layer Security (TLS) PrivateTLS data Web browser Web server ∙ Cryptographic protocol ∘ Provides security on top of reliable transport (TCP) ∘ Used to secure HTTP, SMTP, IMAP, XMPP and others ∙ Security goals ∘ Authentication of server and optionally client ∘ Data integrity (no manipulation of data) ∘ Confidentiality (encryption) Universität Duisburg-Essen Matthäus Wander 2 Verteilte Systeme History ∙ Predecessor: Secure Sockets Layer (SSL) ∘ Developed by Netscape for HTTPS (= HTTP + SSL) ∙ 1994: SSL 2.0 ∘ Insecure, major security weaknesses ∙ 1995: SSL 3.0 ∘ Insecure, deprecated since 2015 (RFC 7568) ∙ 1999: TLS 1.0, minor improvements to SSL 3.0 ∘ Standardization and further development by IETF Universität Duisburg-Essen Matthäus Wander 3 Verteilte Systeme History ∙ 2003: TLS Extensions ∘ New features or security mechanisms (e.g. Encrypt-then-MAC, RFC 7366) ∙ 2006: TLS 1.1 ∘ Security improvements ∙ 2008: TLS 1.2 Presented in this lecture ∘ Added new or replaced old cryptographic algorithms ∙ TLS 1.3 is work in progress as of 2017 ∘ Outlook: new handshake and other major changes Universität Duisburg-Essen Matthäus Wander 4 Verteilte Systeme Protocol Overview Application Layer (e.g. HTTP) Handshake Change Cipher Application Alert Protocol Protocol Spec Protocol Data Protocol Record Protocol Transport Layer (e.g. TCP) ∙ TLS consists of two layers: ∘ Handshake Protocol and other protocols ∘ Record Protocol -
A Systematic Study of Cache Side Channels Across AES Implementations
A Systematic Study of Cache Side Channels across AES Implementations Heiko Mantel1, Alexandra Weber1, and Boris K¨opf 2 1 Computer Science Department, TU Darmstadt, Darmstadt, Germany [email protected], [email protected] 2 IMDEA Software Institute, Madrid, Spain [email protected] Abstract While the AES algorithm is regarded as secure, many imple- mentations of AES are prone to cache side-channel attacks. The lookup tables traditionally used in AES implementations for storing precom- puted results provide speedup for encryption and decryption. How such lookup tables are used is known to affect the vulnerability to side chan- nels, but the concrete effects in actual AES implementations are not yet sufficiently well understood. In this article, we analyze and compare multiple off-the-shelf AES implementations wrt. their vulnerability to cache side-channel attacks. By applying quantitative program analysis techniques in a systematic fashion, we shed light on the influence of im- plementation techniques for AES on cache-side-channel leakage bounds. 1 Introduction The Advanced Encryption Standard (AES) is a widely used symmetric cipher that is approved by the U.S. National Security Agency for security-critical ap- plications [8]. While traditional attacks against AES are considered infeasible as of today, software implementations of AES are known to be highly suscepti- ble to cache side-channel attacks [5, 15, 18, 19, 32]. While such side channels can be avoided by bitsliced implementations [6,23], lookup-table-based implementa- tions, which aim at better performance, are often vulnerable and wide spread. To understand the vulnerability to cache side-channel attacks, recall that the 128bit version of AES relies on 10 rounds of transformations.