PKI Scalability Issues

This report surveys different PKI technologies such as PKIX and SPKI and the issues of PKI that affect scalability. Much focus is spent on certificate revocation methodologies and status verification systems such as CRLs, Delta-CRLs, CRS, Certificate Revocation Trees, Windowed Certificate Revocation, OCSP, SCVP and DVCS.Comment: 23 pages, 2 figure

The Doctrine of Collateral Estoppel in Parole Revocation

In recent years courts have shown more recognition of the rights of parolees and probationers. Spurred by a Supreme Court decision that certain due process protections were applicable to parole revocation procedures, revocation hearings are now providing parolees and probationers some of the procedural protections available to criminal defendants at trial. Policy considerations have dictated, however, that the protections available at revocation hearings must fall far short of conferring upon the accused the full panoply of rights due a defendant at trial. As a result of the Supreme Court\u27s emphasis on the difference between revocation hearings and criminal proceedings, lower courts have held that some constitutional protections available to defendants at trial do not apply at revocation hearings. Thus, the exclusionary rule has been held inapplicable to revocation hearings. This is in contrast to a recent district court decision, Standlee v. Rhay, where it was held that because of the punitive nature of a revocation hearing, it should be treated in some respects as equivalent to a criminal proceeding. These contrasting results are not as inconsistent as they may seem at first glance, but may be harmonized, to some extent, through an analysis of the principles underlying the respective doctrines. Although revocation hearings often present both exclusionary rule and collateral estoppel problems, these are essentially distinct legal concepts

An Identity-Based Group Signature with Membership Revocation in the Standard Model

Group signatures allow group members to sign an arbitrary number\ud of messages on behalf of the group without revealing their\ud identity. Under certain circumstances the group manager holding a\ud tracing key can reveal the identity of the signer from the\ud signature. Practical group signature schemes should support\ud membership revocation where the revoked member loses the\ud capability to sign a message on behalf of the group without\ud influencing the other non-revoked members. A model known as\ud \emph{verifier-local revocation} supports membership revocation.\ud In this model the trusted revocation authority sends revocation\ud messages to the verifiers and there is no need for the trusted\ud revocation authority to contact non-revoked members to update\ud their secret keys. Previous constructions of verifier-local\ud revocation group signature schemes either have a security proof in the\ud random oracle model or are non-identity based. A security proof\ud in the random oracle model is only a heuristic proof and\ud non-identity-based group signature suffer from standard Public Key\ud Infrastructure (PKI) problems, i.e. the group public key is not\ud derived from the group identity and therefore has to be certified.\ud \ud \ud In this work we construct the first verifier-local revocation group\ud signature scheme which is identity-based and which has a security proof in the standard model. In\ud particular, we give a formal security model for the proposed\ud scheme and prove that the scheme has the\ud property of selfless-anonymity under the decision Linear (DLIN)\ud assumption and it is fully-traceable under the\ud Computation Diffie-Hellman (CDH) assumption. The proposed scheme is based on prime order bilinear\ud groups

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

Context dependent revocation in delegated XACML

The XACML standard defines an XML based language for defining access control policies and a related processing model. Recent work aims to add delegation to XACML in order to express the right to administrate XACML policies within XACML itself. The delegation profile draft explains how to validate the right to issue a policy, but there are no provisions for removing a policy. This paper proposes a revocation model for delegated XACML. A novel feature of this model is that whether a revocation is valid or not, depends not only on who issued the revocation, but also on the context in which an attempt to use the revoked policy is done

Labour productivity in state-owned enterprises

In the aftermath of the Global and Financial Crisis (GFC), between 2013 and 2015, the Portuguese government revoked four holidays for both public sector and private employees. We test whether the revocation had an effect on labour productivity in State-Owned Enterprises (SOEs) in Portugal. Moreover, we also study whether such effects are different taking into account the SOEs managed by the Central Government or the Local and Regional Governments. Our results show that revocation of holidays did not impact labour productivity for either central or local and regional government managed SOEs. Though revocation of holidays espoused to improve productivity, the policy seems to have served a ceremonial purpose, but not an economic oneinfo:eu-repo/semantics/publishedVersio