4,665 research outputs found
PKI Safety Net (PKISN): Addressing the Too-Big-to-Be-Revoked Problem of the TLS Ecosystem
In a public-key infrastructure (PKI), clients must have an efficient and
secure way to determine whether a certificate was revoked (by an entity
considered as legitimate to do so), while preserving user privacy. A few
certification authorities (CAs) are currently responsible for the issuance of
the large majority of TLS certificates. These certificates are considered valid
only if the certificate of the issuing CA is also valid. The certificates of
these important CAs are effectively too big to be revoked, as revoking them
would result in massive collateral damage. To solve this problem, we redesign
the current revocation system with a novel approach that we call PKI Safety Net
(PKISN), which uses publicly accessible logs to store certificates (in the
spirit of Certificate Transparency) and revocations. The proposed system
extends existing mechanisms, which enables simple deployment. Moreover, we
present a complete implementation and evaluation of our scheme.Comment: IEEE EuroS&P 201
Formal Analysis of V2X Revocation Protocols
Research on vehicular networking (V2X) security has produced a range of
security mechanisms and protocols tailored for this domain, addressing both
security and privacy. Typically, the security analysis of these proposals has
largely been informal. However, formal analysis can be used to expose flaws and
ultimately provide a higher level of assurance in the protocols.
This paper focusses on the formal analysis of a particular element of
security mechanisms for V2X found in many proposals: the revocation of
malicious or misbehaving vehicles from the V2X system by invalidating their
credentials. This revocation needs to be performed in an unlinkable way for
vehicle privacy even in the context of vehicles regularly changing their
pseudonyms. The REWIRE scheme by Forster et al. and its subschemes BASIC and
RTOKEN aim to solve this challenge by means of cryptographic solutions and
trusted hardware.
Formal analysis using the TAMARIN prover identifies two flaws with some of
the functional correctness and authentication properties in these schemes. We
then propose Obscure Token (OTOKEN), an extension of REWIRE to enable
revocation in a privacy preserving manner. Our approach addresses the
functional and authentication properties by introducing an additional key-pair,
which offers a stronger and verifiable guarantee of successful revocation of
vehicles without resolving the long-term identity. Moreover OTOKEN is the first
V2X revocation protocol to be co-designed with a formal model.Comment: 16 pages, 4 figure
Security and Privacy Issues in Wireless Mesh Networks: A Survey
This book chapter identifies various security threats in wireless mesh
network (WMN). Keeping in mind the critical requirement of security and user
privacy in WMNs, this chapter provides a comprehensive overview of various
possible attacks on different layers of the communication protocol stack for
WMNs and their corresponding defense mechanisms. First, it identifies the
security vulnerabilities in the physical, link, network, transport, application
layers. Furthermore, various possible attacks on the key management protocols,
user authentication and access control protocols, and user privacy preservation
protocols are presented. After enumerating various possible attacks, the
chapter provides a detailed discussion on various existing security mechanisms
and protocols to defend against and wherever possible prevent the possible
attacks. Comparative analyses are also presented on the security schemes with
regards to the cryptographic schemes used, key management strategies deployed,
use of any trusted third party, computation and communication overhead involved
etc. The chapter then presents a brief discussion on various trust management
approaches for WMNs since trust and reputation-based schemes are increasingly
becoming popular for enforcing security in wireless networks. A number of open
problems in security and privacy issues for WMNs are subsequently discussed
before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the
author's previous submission in arXiv submission: arXiv:1102.1226. There are
some text overlaps with the previous submissio
Merging and Extending the PGP and PEM Trust Models - the ICE-TEL Trust Model
The ICE-TEL project is a pan-European project that is building an Internet X.509 based certification infrastructure throughout Europe, plus several secure applications that will use it. This paper describes the trust model that is being implemented by the project. A trust model specifies the means by which a user may build trust in the assertion that a remote user is really who he purports to be (authentication) and that he does in fact have a right to access the service or information that he is requesting (authorization). The ICE-TEL trust model is based on a merging of and extensions to the existing Pretty Good Privacy (PGP) web of trust and Privacy Enhanced Mail (PEM) hierarchy of trust models, and is called a web of hierarchies trust model. The web of hierarchies model has significant advantages over both of the previous models, and these are highlighted here. The paper further describes the way that the trust model is enforced through some of the new extensions in the X.509 V3 certificates, and gives examples of its use in different scenarios
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