Soft Constraint Programming to Analysing Security Protocols

Security protocols stipulate how the remote principals of a computer network should interact in order to obtain specific security goals. The crucial goals of confidentiality and authentication may be achieved in various forms, each of different strength. Using soft (rather than crisp) constraints, we develop a uniform formal notion for the two goals. They are no longer formalised as mere yes/no properties as in the existing literature, but gain an extra parameter, the security level. For example, different messages can enjoy different levels of confidentiality, or a principal can achieve different levels of authentication with different principals. The goals are formalised within a general framework for protocol analysis that is amenable to mechanisation by model checking. Following the application of the framework to analysing the asymmetric Needham-Schroeder protocol, we have recently discovered a new attack on that protocol as a form of retaliation by principals who have been attacked previously. Having commented on that attack, we then demonstrate the framework on a bigger, largely deployed protocol consisting of three phases, Kerberos.Comment: 29 pages, To appear in Theory and Practice of Logic Programming (TPLP) Paper for Special Issue (Verification and Computational Logic

A Multi-Factor Homomorphic Encryption based Method for Authenticated Access to IoT Devices

Authentication is the first defence mechanism in many electronic systems, including Internet of Things (IoT) applications, as it is essential for other security services such as intrusion detection. As existing authentication solutions proposed for IoT environments do not provide multi-level authentication assurance, particularly for device-to-device authentication scenarios, we recently proposed the M2I (Multi-Factor Multi-Level and Interaction based Authentication) framework to facilitate multi-factor authentication of devices in device-to-device and device-to-multiDevice interactions. In this paper, we extend the framework to address group authentication. Two Many-to-One (M2O) protocols are proposed, the Hybrid Group Authentication and Key Acquisition (HGAKA) protocol and the Hybrid Group Access (HGA) protocol. The protocols use a combination of symmetric and asymmetric cryptographic primitives to facilitate multifactor group authentication. The informal analysis and formal security verification show that the protocols satisfy the desirable security requirements and are secure against authentication attacks

Formal verification of secondary authentication protocol for 5G secondary authentication

The Fifth-Generation mobile network (5G) will enable interconnectivity between the Home Network (HN) and Data Network (DN) whereby mobile users with their User Equipment (UE) will be able to access services provided by external Service Providers (SP) seamlessly. The mobile user and SP will rely on security assurances provided by authentication protocols used. For 5G, primary authentication between the UE and the HN has been defined and specified by the Third Generation Partnership Project (3GPP) while the secondary authentication has also been defined but not specified. 3GPP recommends the Extensible Authentication Protocol (EAP) framework for secondary authentication between the UE and the SP. However, the secondary authentication methods have not been formally verified, so this paper proposes a Secondary Authentication Protocol (SAP) for service authentication and provides a comprehensive formal analysis using ProVerif a security protocol verifier. Finally, it conducts a security analysis on the protocol's security properties

An Efficient Generic Framework for Three-Factor Authentication With Provably Secure Instantiation

Remote authentication has been widely studied and adapted in distributed systems. The security of remote authentication mechanisms mostly relies on one of or the combination of three factors: 1) something users know - password; 2) something users have - smart card; and 3) something users are - biometric characteristics. This paper introduces an efficient generic framework for three-factor authentication. The proposed generic framework enhances the security of existing two-factor authentication schemes by upgrading them to three-factor authentication schemes, without exposing user privacy. In addition, we present a case study by upgrading a secure two-factor authentication scheme to a secure three-factor authentication scheme. Furthermore, implementation analysis, formal proof, and privacy discussion are provided to show that the derived scheme is practical, secure, and privacy preserving

Soft Constraint Programming to Analysing Security Protocols

Security protocols stipulate how remote principals of a computer network should interact in order to obtain specific security goals. The crucial goals of confidentiality and authentication may be achieved in various forms. Using soft (rather than crisp) constraints, we develop a uniform formal notion for the two goals. They are no longer formalised as mere yes/no properties as in the existing literature, but gain an extra parameter, the security level. For example, different messages can enjoy different levels of confidentiality, or a principal can achieve different levels of authentication with different principals. The goals are formalised within a general framework for protocol analysis that is amenable to mechanisation by model checking. Following the application of the framework to analysing the asymmetric Needham- Schroeder protocol, we have recently discovered a new attack on that protocol. We briefly describe that attack, and demonstrate the framework on a bigger, largely deployed protocol consisting of three phases, Kerberos

Data Minimisation in Communication Protocols: A Formal Analysis Framework and Application to Identity Management

With the growing amount of personal information exchanged over the Internet, privacy is becoming more and more a concern for users. One of the key principles in protecting privacy is data minimisation. This principle requires that only the minimum amount of information necessary to accomplish a certain goal is collected and processed. "Privacy-enhancing" communication protocols have been proposed to guarantee data minimisation in a wide range of applications. However, currently there is no satisfactory way to assess and compare the privacy they offer in a precise way: existing analyses are either too informal and high-level, or specific for one particular system. In this work, we propose a general formal framework to analyse and compare communication protocols with respect to privacy by data minimisation. Privacy requirements are formalised independent of a particular protocol in terms of the knowledge of (coalitions of) actors in a three-layer model of personal information. These requirements are then verified automatically for particular protocols by computing this knowledge from a description of their communication. We validate our framework in an identity management (IdM) case study. As IdM systems are used more and more to satisfy the increasing need for reliable on-line identification and authentication, privacy is becoming an increasingly critical issue. We use our framework to analyse and compare four identity management systems. Finally, we discuss the completeness and (re)usability of the proposed framework

Formal Verification of Security Protocol Implementations: A Survey

Automated formal verification of security protocols has been mostly focused on analyzing high-level abstract models which, however, are significantly different from real protocol implementations written in programming languages. Recently, some researchers have started investigating techniques that bring automated formal proofs closer to real implementations. This paper surveys these attempts, focusing on approaches that target the application code that implements protocol logic, rather than the libraries that implement cryptography. According to these approaches, libraries are assumed to correctly implement some models. The aim is to derive formal proofs that, under this assumption, give assurance about the application code that implements the protocol logic. The two main approaches of model extraction and code generation are presented, along with the main techniques adopted for each approac

RUASN: A Robust User Authentication Framework for Wireless Sensor Networks

In recent years, wireless sensor networks (WSNs) have been considered as a potential solution for real-time monitoring applications and these WSNs have potential practical impact on next generation technology too. However, WSNs could become a threat if suitable security is not considered before the deployment and if there are any loopholes in their security, which might open the door for an attacker and hence, endanger the application. User authentication is one of the most important security services to protect WSN data access from unauthorized users; it should provide both mutual authentication and session key establishment services. This paper proposes a robust user authentication framework for wireless sensor networks, based on a two-factor (password and smart card) concept. This scheme facilitates many services to the users such as user anonymity, mutual authentication, secure session key establishment and it allows users to choose/update their password regularly, whenever needed. Furthermore, we have provided the formal verification using Rubin logic and compare RUASN with many existing schemes. As a result, we found that the proposed scheme possesses many advantages against popular attacks, and achieves better efficiency at low computation cost

Analysing the EAP-TLS handshake and the 4-way handshake of the 802.11i standard

The IEEE 802.11i standard has been designed to enhance security in wireless networks. The EAP-TLS handshake aims to provide mutual authentication between supplicant and authentication server, and then derive the Pairwise Master Key (PMK). In the 4 -way handshake the supplicant and the authenticator use PMK to derive a fresh pairwise transient key (PTK). The PMK is not used directly for security while assuming the supplicant and authenticator have the same PMK before running 4- way handshake. In this paper, the EAP-TLS handshake and the 4-way handshake phases have been analysed with a proposed framework using Isabelle tool. In the analysis, we have found a new Denial-of-Service (DoS) attack in the 4-way handshake. The attack prevents the authenticator from receiving message 4 after the supplicant sends it out. This attack forces the authenticator to re-send the message 3 until time out and subsequently to de-authenticate supplicant. This paper has proposed improvements to the 4-way handshake to avoid the Denial-of-Service attack

Formally based semi-automatic implementation of an open security protocol

International audienceThis paper presents an experiment in which an implementation of the client side of the SSH Transport Layer Protocol (SSH-TLP) was semi-automatically derived according to a model-driven development paradigm that leverages formal methods in order to obtain high correctness assurance. The approach used in the experiment starts with the formalization of the protocol at an abstract level. This model is then formally proved to fulfill the desired secrecy and authentication properties by using the ProVerif prover. Finally, a sound Java implementation is semi-automatically derived from the verified model using an enhanced version of the Spi2Java framework. The resulting implementation correctly interoperates with third party servers, and its execution time is comparable with that of other manually developed Java SSH-TLP client implementations. This case study demonstrates that the adopted model-driven approach is viable even for a real security protocol, despite the complexity of the models needed in order to achieve an interoperable implementation