A Holistic Systems Security Approach Featuring Thin Secure Elements for Resilient IoT Deployments

© 2020 by the authors. This is an open access article distributed under the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.IoT systems differ from traditional Internet systems in that they are different in scale, footprint, power requirements, cost and security concerns that are often overlooked. IoT systems inherently present different fail-safe capabilities than traditional computing environments while their threat landscapes constantly evolve. Further, IoT devices have limited collective security measures in place. Therefore, there is a need for different approaches in threat assessments to incorporate the interdependencies between different IoT devices. In this paper, we run through the design cycle to provide a security-focused approach to the design of IoT systems using a use case, namely, an intelligent solar-panel project called Daedalus. We utilise STRIDE/DREAD approaches to identify vulnerabilities using a thin secure element that is an embedded, tamper proof microprocessor chip that allows the storage and processing of sensitive data. It benefits from low power demand and small footprint as a crypto processor as well as is compatible with IoT 29 requirements. Subsequently, a key agreement based on an asymmetric cryptographic scheme, namely B-SPEKE was used to validate and authenticate the source. We find that end-to-end and independent stand-alone procedures used for validation and encryption of the source data originating from the solar panel are cost-effective in that the validation is carried out once and not several times in the chain as is often the case. The threat model proved useful not so much as a panacea for all threats but provided the framework for the consideration of known threats, and therefore appropriate mitigation plans to be deployed.Peer reviewe

Enhancing Privacy in Cryptographic Protocols

For the past three decades, a wide variety of cryptographic protocols have been proposed to solve secure communication problems even in the presence of adversaries. The range of this work varies from developing basic security primitives providing confidentiality and authenticity to solving more complex, application-specific problems. However, when these protocols are deployed in practice, a significant challenge is to ensure not just security but also privacy throughout these protocols' lifetime. As computer-based devices are more widely used and the Internet is more globally accessible, new types of applications and new types of privacy threats are being introduced. In addition, user privacy (or equivalently, key privacy) is more likely to be jeopardized in large-scale distributed applications because the absence of a central authority complicates control over these applications. In this dissertation, we consider three relevant cryptographic protocols facing user privacy threats when deployed in practice. First, we consider matchmaking protocols among strangers to enhance their privacy by introducing the "durability" and "perfect forward privacy" properties. Second, we illustrate the fragility of formal definitions with respect to password privacy in the context of password-based authenticated key exchange (PAKE). In particular, we show that PAKE protocols provably meeting the existing formal definitions do not achieve the expected level of password privacy when deployed in the real world. We propose a new definition for PAKE that is tightly connected to what is actually desired in practice and suggest guidelines for realizing this definition. Finally, we answer to a specific privacy question, namely whether privacy properties of symmetric-key encryption schemes obtained by non-tight reduction proofs are retained in the real world. In particular, we use the privacy notion of "multi-key hiding" property and show its non-tight relation with the IND$-CPA property of symmetric-key schemes. We use the experimental result by Gligor et al. to show how a real attack breaks the "multi-key hiding" property of IND$-CPA symmetric-key encryption schemes with high probability in practice. Finally, we identify schemes that satisfy the "multi-key hiding" and enhance key privacy in the real world

Universally Composable Relaxed Password Authenticated Key Exchange

International audienceProtocols for password authenticated key exchange (PAKE) allow two parties who share only a weak password to agree on a cryptographic key. We revisit the notion of PAKE in the universal composabil-ity (UC) framework, and propose a relaxation of the PAKE functionality of Canetti et al. that we call lazy-extraction PAKE (lePAKE). Our relaxation allows the ideal-world adversary to postpone its password guess until after a session is complete. We argue that this relaxed notion still provides meaningful security in the password-only setting. As our main result, we show that several PAKE protocols that were previously only proven secure with respect to a "game-based" definition of security can be shown to UC-realize the lePAKE functionality in the random-oracle model. These include SPEKE, SPAKE2, and TBPEKE, the most efficient PAKE schemes currently known

개선된 인증과 키 분배 기법

학위논문 (박사)-- 서울대학교 대학원 : 수리과학부, 2014. 2. 김명환.Nowadays, anonymity property of user authentication scheme becomes important. From 2003, Park et al., Juang et al., and other researchers proposed a useful, secure and efficient authenticated-key exchange scheme. However, There schemes did not provide the useful methods against the various efficient attacks. They argued that they provided the identity privacy- mutual authentication-half-forward secrecy. But their suggestions have limited solutions. So we have researched the about 30 papers and suggested an improved authentication and key exchange scheme. Then, we show that the proposed scheme is secure against the various attacks methods (linear attack, inverse, dictionary, MTMD attacks etc).Chapter 1 Introduction ........................................................ 6 1.1 Motivation ...............................................................................6 1.2 Organization ............................................................................8 Chapter 2 Secure Authenticated Key Exchange .................. 11 2.1 AKE Security ........................................................................11 2.2 Protocol Attack Types ...........................................................17 Chapter 3Secure Authenticated Key Exchange ................... 19 3.1 The Authentication Key Protocol..........................................19 3.2 General Security-Analysis Discussion..................................26 Chapter 4Authenticated Key Exchange Protocol................ 40 4.1 The Improved AKE ...............................................................41 4.2 An Improved Anonymous AKE Scheme ..............................62 Chapter 5Conclusion ...................................................... 75 Bibliography .................................................................... 77 Abstract ........................................................................... 87Docto

Password-Authenticated Key Exchange from Group Actions

We present two provably secure password-authenticated key exchange (PAKE) protocols based on a commutative group action. To date the most important instantiation of isogeny-based group actions is given by CSIDH. To model the properties more accurately, we extend the framework of cryptographic group actions (Alamati et al., ASIACRYPT 2020) by the ability of computing the quadratic twist of an elliptic curve. This property is always present in the CSIDH setting and turns out to be crucial in the security analysis of our PAKE protocols. Despite the resemblance, the translation of Diffie-Hellman based PAKE protocols to group actions either does not work with known techniques or is insecure ( How not to create an isogeny-based PAKE , Azarderakhsh et al., ACNS 2020). We overcome the difficulties mentioned in previous work by using a bit-by-bit approach, where each password bit is considered separately. Our first protocol $\mathsf{X\text{-}GA\text{-}PAKE}_\ell$ can be executed in a single round. Both parties need to send two set elements for each password bit in order to prevent offline dictionary attacks. The second protocol $\mathsf{Com\text{-}GA\text{-}PAKE}_\ell$ requires only one set element per password bit, but one party has to send a commitment on its message first. We also discuss different optimizations that can be used to reduce the computational cost. We provide comprehensive security proofs for our base protocols and deduce security for the optimized versions

Exploration of the Security and Usability of the FIDO2 Authentication Protocol

Gemstone Team PASSFast IDentity Online (FIDO) is a passwordless authentication protocol for the web that leverages public key cryptography and trusted devices to avoid shared secrets on servers. The current version of FIDO, FIDO2, has become widespread and is directly integrated into popular systems such as Windows Hello and Android OS. This thesis details two contributions to the advancement of FIDO2. The first is a modification to the protocol which uses Trusted Execution Environments to resolve security vulnerabilities in the Client To Authenticator Protocol Version 2 (CTAP2), which is a component of FIDO2. It is formally demonstrated that this modification provides a stronger security assumption than CTAP2. The second contribution is an outline of procedures and resources for future researchers to carry out a study of the usability of FIDO2 authenticators via a within-subjects experiment. In the study, subjects register an account on a custom web app using both passwords and FIDO2 credentials. The web app collects metrics about user behavior such as timing information for authentication sessions. Over the course of a week, subjects log in to the same web app every day using both authentication methods. Subjects complete entrance and exit surveys based on the System Usability Scale (SUS) according to their experiences. The surveys and user metrics would then be analyzed to determine whether users perceive FIDO2 as more usable than passwords

Secure Key Exchange Against Man-in-the-Middle Attack: Modified Diffie-Hellman Protocol

One of the most famous key exchange protocols is Diffie-Hellman Protocol (DHP) which is a widely used technique on which key exchange systems around the world depend. This protocol is simple and uncomplicated, and its robustness is based on the Discrete Logarithm Problem (DLP). Despite this, he is considered weak against the man-in-the-middle attack. This article presents a completely different version of the DHP protocol. The proposed version is based on two verification stages. In the first step, we check if the pseudo-random value α that Alice sends to Bob has been manipulated! In the second step, we make sure that the random value β that Bob sends to Alice is not manipulated. The man-in-the-middle attacker Eve can impersonate neither Alice nor Bob, manipulate their exchanged values, or discover the secret encryption key

A multifaceted formal analysis of end-to-end encrypted email protocols and cryptographic authentication enhancements

Largely owing to cryptography, modern messaging tools (e.g., Signal) have reached a considerable degree of sophistication, balancing advanced security features with high usability. This has not been the case for email, which however, remains the most pervasive and interoperable form of digital communication. As sensitive information (e.g., identification documents, bank statements, or the message in the email itself) is frequently exchanged by this means, protecting the privacy of email communications is a justified concern which has been emphasized in the last years. A great deal of effort has gone into the development of tools and techniques for providing email communications with privacy and security, requirements that were not originally considered. Yet, drawbacks across several dimensions hinder the development of a global solution that would strengthen security while maintaining the standard features that we expect from email clients. In this thesis, we present improvements to security in email communications. Relying on formal methods and cryptography, we design and assess security protocols and analysis techniques, and propose enhancements to implemented approaches for end-to-end secure email communication. In the first part, we propose a methodical process relying on code reverse engineering, which we use to abstract the specifications of two end-to-end security protocols from a secure email solution (called pEp); then, we apply symbolic verification techniques to analyze such protocols with respect to privacy and authentication properties. We also introduce a novel formal framework that enables a system's security analysis aimed at detecting flaws caused by possible discrepancies between the user's and the system's assessment of security. Security protocols, along with user perceptions and interaction traces, are modeled as transition systems; socio-technical security properties are defined as formulas in computation tree logic (CTL), which can then be verified by model checking. Finally, we propose a protocol that aims at securing a password-based authentication system designed to detect the leakage of a password database, from a code-corruption attack. In the second part, the insights gained by the analysis in Part I allow us to propose both, theoretical and practical solutions for improving security and usability aspects, primarily of email communication, but from which secure messaging solutions can benefit too. The first enhancement concerns the use of password-authenticated key exchange (PAKE) protocols for entity authentication in peer-to-peer decentralized settings, as a replacement for out-of-band channels; this brings provable security to the so far empirical process, and enables the implementation of further security and usability properties (e.g., forward secrecy, secure secret retrieval). A second idea refers to the protection of weak passwords at rest and in transit, for which we propose a scheme based on the use of a one-time-password; furthermore, we consider potential approaches for improving this scheme. The hereby presented research was conducted as part of an industrial partnership between SnT/University of Luxembourg and pEp Security S.A

New Anonymity Notions for Identity-Based Encryption

The original publication is available at www.springerlink.comInternational audienceIdentity-based encryption is a very convenient tool to avoid key management. Recipient-privacy is also a major concern nowadays. To combine both, anonymous identity-based encryption has been proposed. This paper extends this notion to stronger adversaries (the authority itself). We discuss this new notion, together with a new kind of non-malleability with respect to the identity, for several existing schemes. Inter- estingly enough, such a new anonymity property has an independent application to password-authenticated key exchange. We thus come up with a new generic framework for password-authenticated key exchange, and a concrete construction based on pairings