Security Protocol Analysis with Improved Authentication Tests

With the rise of the Internet and other open networks, a large number of security protocols have been developed and deployed in order to provide secure communication. The analysis of such security protocols has turned out to be extremely difficult for humans, as witnessed by the fact that many protocols were found to be flawed after deployment. This has driven the research in formal analysis of security protocols. Unfortunately, there are no effective approaches yet for constructing correct and efficient protocols, and work on concise formal logics that might allow one to easily prove that a protocol is correct in a formal model, is still ongoing. The most effective approach so far has been automated falsification or verification of such protocols with state-of-the-art tools such as ProVerif [1] or the Avispa tools [2]. These tools have shown to be effective at finding attacks on protocols (Avispa) or establishing correctness of protocols (ProVerif).KeywordsOperational SemanticSecurity ProtocolAttack TraceComputer Security Foundation WorkshopSecurity ClaimThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Recent technologies have cleared the way for large scale application of electronic communication. The open and distributed nature of these communications implies that the communication medium is no longer completely controlled by the communicating parties. As a result, there has been an increasing demand for research in establishing secure communications over insecure networks, by means of security protocols. In this thesis, a formal model for the description and analysis of security protocols at the process level is developed. At this level, under the assumption of perfect cryptography, the analysis focusses on detecting aws and vulnerabilities of the security protocol. Starting from ??rst principles, operational semantics are developed to describe security protocols and their behaviour. The resulting model is parameterized, and can e.g. capture various intruder models, ranging from a secure network with no intruder, to the strongest intruder model known in literature. Within the security protocol model various security properties are de??ned, such as secrecy and various forms of authentication. A number of new results about these properties are formulated and proven correct. Based on the model, an automated veri??cation procedure is developed, which signi ??cantly improves over existing methods. The procedure is implemented in a prototype, which outperforms other tools. Both the theory and tool are applied in two novel case studies. Using the tool prototype, new results are established in the area of protocol composition, leading to the discovery of a class of previously undetected attacks. Furthermore, a new protocol in the area of multiparty authentication is developed. The resulting protocol is proven correct within the framework.

Protocol security in a composition protocol environment has always been an open problem in the field of formal analysis and verification of security protocols. As a well-known tool to analyze and verify the logical consistency of concurrent systems, SPIN (Simple Promela Interpreter) has been widely used in the analysis and verification of the security of a single protocol. There is no special research on the verification of protocol security in a composition protocol environment. To solve this problem, firstly, a formal analysis method for composition protocol based on SPIN is proposed, and a formal description of protocol operation semantics is given. Then the attacker model is formalized, and a message specification method based on field detection and component recognition is presented to alleviate the state explosion problem. Finally, the NSB protocol and the NSL protocol are used as examples for compositional analysis. It is demonstrated that the proposed method can effectively verify the security of the protocol in a composition protocol environment and enhance the efficiency of composition protocol verification.

Security protocols flaws are notoriously difficult to detect. Comparatively little attention has been given to logics of knowledge, although such logics have been proven to be very useful in the specifications of protocols for communication systems. We address ourselves to the analysis of security protocols under the Dolev-Yao model by using a logic of algorithmic knowledge, and propose a general method to describe formally the data structures used in the verification, such as messages, traces, intruders, and so on. We explore the use of our methodology for the verification of security protocols. The Horng-Hsu attack to Helsinki protocol has been found successfully in this setting by using SPIN.

Security protocols are notoriously difficult to debug. One approach to the automatic verification of security protocols with a bounded set of agents uses logic programming with analysis and synthesis rules to describe how the attacker gains information and constructs new messages.We propose a generic approach to verifying security protocols in Spin. The dynamic process creation mechanism of Spin is used to nondeterministically create different combinations of role instantiations. We incorporate the synthesis and analysis features of the logic programming approach to describe how the intruder learns information and replays it back into the system. We formulate a generic “loss of secrecy” property that is flagged whenever the intruder learns private information from an intercepted message. We also describe a simplification of the Dolev-Yao attacker model that suffices to analyze secrecy properties.KeywordsAuthentication ProtocolSecurity ProtocolCryptographic ProtocolSecrecy PropertyModel Check ApproachThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

First-order logic resolution is a standard way to automate the verification of security protocols. However, it sometimes fails to produce security proofs for secure protocols because of the detection of false attacks. For the verification of a bounded number of sessions, false attacks can be avoided by introducing rigid variables. Unfortunately, this yields complicated resolution procedures. We show here that there is a simple translation of the security problem for a bounded number of sessions into first-order logic, that does not introduce false attacks. This is shown by translating clauses involving rigid variables into classical first-order clauses, while preserving satisfiability. We illustrate this approach by giving a complete and terminating strategy for a first-order logic fragment resulting from the above translation, that yields a decision procedure for a bounded number of sessions.

Security protocol verification has been a very active research area since the 1990s. This paper surveys various approaches in this area, considering the verification in the symbolic model, as well as the more recent approaches that rely on the computational model or that verify protocol implementations rather than specifications. Additionally, we briefly describe our symbolic security protocol verifier ProVerif and situate it among these approaches.KeywordsSecurity ProtocolSecurity PropertyComputer SecuritySymbolic ModelHorn ClauseThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This paper points out the limitations of the structure of authentication test (AT) and the semantics of strand space, which causes that it is incomplete, or produces erroneous authentication when using AT to analyze multi-party security protocols. And at present, the existing improved schemes of AT have the same limitations, since they are all proposed based on the original frame structure of AT. By transferring the node relations of strand space into the component, and introducing the concept of Attack Equivalence Class (AEC), Component Transform Chain(CTC) and so on, this paper proposed a new AT scheme, with corresponding formal proof and instance verification. The new method not only breaks through the above limitations, but also improves the efficiency of implementation and is easy to realize automation.

Discrete event systems approach to the verification of the information flow properties in secure protocols

: When a distributed systems protocol is used in a particular context as part of a solution to a larger problem, additional information may be generated from the context. Such information may be used for optimization of the system, and, in the case of security protocols, may be of use to the adversary for attacks. The project conducted a case study of the application of the epistemic model checker MCK to automatically detect such optimization opportunities, and to verify that the protocol remains secure in the mode of use. The particular protocol studied was Chaum's Dining Cryptographers protocol, a security protocol that allows a single agent to anonymously transmit a signal. The context of use considered was a more general 2-phase protocol for anonymous broadcast by an arbitrary number of agents, also proposed by Chaum. The aims of the 2-phase anonymous broadcast protocol were formulated as a knowledge-based program, and an iterative process of model checking and manual counter-example guided refinement was followed to converge on implementations of this knowledge-based program in which local predicates were identified that correspond precisely to the knowledge conditions in the knowledge-based program. This analysis demonstrated that the 2-phase protocol contains some quite subtle flows of information that can be used to optimize its performance, but no violation of the anonymity property was found. As an additional contribution of the research, a formal abstraction technique was developed, and proved correct, for epistemic model checking of protocols that call the Dining Cryptographers protocol as a subroutine. Experimental results show that the optimization improves epistemic model checking performance by orders of magnitude and enables problems of larger scale to be attacked.

Timed Intruder Models have been proposed for the verification of Cyber-Physical Security Protocols (CPSP) amending the traditional Dolev-Yao intruder to obey the physical restrictions of the environment. Since to learn a message, a Timed Intruder needs to wait for a message to arrive, mounting an attack may depend on where Timed Intruders are. It may well be the case that in the presence of a great number of intruders there is no attack, but there is an attack in the presence of a small number of well placed intruders. Therefore, a major challenge for the automated verification of CPSP is to determine how many Timed Intruders to use and where should they be placed. This paper answers this question by showing it is enough to use the same number of Timed Intruders as the number of participants. We also report on some preliminary experimental results in discovering attacks in CPSP.

Rewriting Modulo SMT combines two powerful automated deduction techniques (1) rewriting and (2) SMT-solving. Rewriting enables the specification of behavior of systems using rewriting rules, while SMT theories specify system properties. Rewriting Modulo SMT is enabled by combining existing tools, such as Maude and SMT solvers. Search algorithms used for carrying out Rewriting Modulo SMT, however, cannot exploit the incremental solving features available in SMT solvers as they are based on breadth-first search. This paper addresses this limitation by proposing Incremental Rewriting Modulo SMT Theories, which is a syntactical restriction to rewriting rules. This restriction turns out to naturally be used in several applications of Rewriting Modulo SMT, including the verification of algorithms, cyber-physical systems, and security protocols. Moreover, we propose a Hybrid-Search algorithm for Incremental Rewriting Modulo SMT Theories that combines breadth-first search and depth-first search, thus enabling incremental SMT-solving. We demonstrate through a collection of existing benchmarks that the Hybrid-Search algorithm can achieve a 10 times performance improvement in verification times.

We present a new model for automated verification of security protocols, permitting the use of an unbounded number of protocol runs. We prove its correctness, completeness and also that it terminates. It has been implemented and its efficiency is clearly shown by the number of protocols successfully studied. In particular, we present an attack previously unreported on the Denning-Sacco symmetric key protocol.

Security protocols have been analysed using a variety of tools and focusing on a variety of properties. Most findings assume the ever so popular Dolev-Yao threat model. A more recent threat model called the Rational Attacker [1] sees each protocol participant decide whether or not to conform to the protocol upon their own cost/benefit analysis. Each participant neither colludes nor shares knowledge with anyone, a feature that rules out the applicability of existing equivalence results in the Dolev-Yao model. Aiming at mechanical validation, we abstract away the actual cost/benefit analysis and obtain the General Attacker threat model, which sees each principal blindly act as a Dolev-Yao attacker.The analysis of security protocols under the General Attacker threat model brings forward yet more insights: retaliation attacks and anticipation attacks are our main findings, while the tool support can scale up to the new analysis at a negligible price. The general threat model for security protocols based on set-rewriting that was adopted in AVISPA [2] is leveraged so as to express the General Attacker. The state-of-the-art model checker SATMC [3] is then used to automatically validate a protocol under the new threats, so that retaliation and anticipation attacks can automatically be found.KeywordsModel CheckSecurity ProtocolCryptographic ProtocolThreat ModelGeneral AttackThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

The analysis of security protocols is of great significance to ensure the safe communication of computer networks. Using formal methods to analyze security protocols has been a research hotspot in this field. Based on the run modes method and Petri net, this paper presents a specific method for analyzing security protocols. Firstly, the concepts of basic Petri net model (BPN) and attack Petri net model (APN) of protocol run modes are given, then the algorithm for constructing APN through BPN is proposed. Finally, the effectiveness of this method is illustrated by analyzing Helsinki protocol.