A DNA Vaccine against Chikungunya Virus Is Protective in Mice and Induces Neutralizing Antibodies in Mice and Nonhuman Primates

Chikungunya virus (CHIKV) is an emerging mosquito-borne alphavirus indigenous to tropical Africa and Asia. Acute illness is characterized by fever, arthralgias, conjunctivitis, rash, and sometimes arthritis. Relatively little is known about the antigenic targets for immunity, and no licensed vaccines or therapeutics are currently available for the pathogen. While the Aedes aegypti mosquito is its primary vector, recent evidence suggests that other carriers can transmit CHIKV thus raising concerns about its spread outside of natural endemic areas to new countries including the U.S. and Europe. Considering the potential for pandemic spread, understanding the development of immunity is paramount to the development of effective counter measures against CHIKV. In this study, we isolated a new CHIKV virus from an acutely infected human patient and developed a defined viral challenge stock in mice that allowed us to study viral pathogenesis and develop a viral neutralization assay. We then constructed a synthetic DNA vaccine delivered by in vivo electroporation (EP) that expresses a component of the CHIKV envelope glycoprotein and used this model to evaluate its efficacy. Vaccination induced robust antigen-specific cellular and humoral immune responses, which individually were capable of providing protection against CHIKV challenge in mice. Furthermore, vaccine studies in rhesus macaques demonstrated induction of nAb responses, which mimicked those induced in convalescent human patient sera. These data suggest a protective role for nAb against CHIKV disease and support further study of envelope-based CHIKV DNA vaccines

Dynamic trust enhanced security model for trusted platform based services

Binary attestation in trusted computing platforms provide the ability to reason about the state of a system using hash measurements. Property based attestation, an extension of binary attestation enables more meaningful attestation by abstracting low level binary values to high level security properties or functions of systems. In this paper, we propose TESM: A Trust Enhanced Secure Model for trusted computing platforms. We argue that given the nature of both binary and property based attestation mechanisms, an attestation requester cannot be absolutely certain if an attesting platform will behave as it is expected to behave. TESM uses a hybrid trust model based on subjective logic to combine 'hard' trust from measurements and properties and 'soft' trust from past experiences and recommendations to reduce such uncertainties. We believe that such a model will enable better reasoning about the trustworthiness of attesting platforms and thereby facilitate better security decision making.10 page(s

Modelling Dynamic Trust with Property Based Attestation in Trusted Platforms

Abstract. Binary attestation in trusted computing provides the ability to reason about the state of a platform using integrity measurements. Property based attestation, an extension of binary attestation enables more meaningful attestation by abstracting low level binary values to high level security properties or functions of platforms. We believe that despite having trusted processes for integrity measurement, binary and property based attestation may still lead to ambiguities. These ambiguities may reduce the overall trust that can be placed on the measurements and properties that are attested by a platform. To address this issue, we propose TESM: a Trust Enhanced Security Model for trusted computing platforms. The overall aim of the model is to reduce the ambiguities and thereby enable better reasoning of properties that are satisfied by a platform with improved clarity

Analysis of Property Based Attestation in Trusted Platforms

Binary attestation in trusted computing platforms provide the ability to reason about the state of a system using hash measurements. Property based attestation on the other hand enables more meaningful attestation by abstracting low level binary values to high level security properties or functions of systems. In this paper, we try to understand the kind of security properties that trusted platforms can attest. We propose that security properties can have different levels of granularity and provide a pyramid model that classifies properties at four different levels. We leverage the Common Criteria framework for security requirements to provide examples of such properties. The model is then implemented in the context of authorisation for Web services.8 page(s

A Property-dependent agent transfer protocol

This paper examines how a secure agent transfer protocol based upon TCG-defined mechanisms can be improved using property-based platform state information. In doing so, we demonstrate a practical implementation of property-based platform attestation using an enhanced version of the component property certificates defined in [16]. To illustrate our solution we provide examples of properties and component property certificates given a mobile aglet that is destined to execute on a group of devices, where the mobile aglet originator wishes to protect the confidentiality of the aglet code.24 page(s

Trust management for trusted computing platforms in web services

The concept of trusted platforms using trusted computing technology such as the Trusted Platform Module (TPM) is becoming significant in that such technologies are being increasingly available in PCs and mobile devices today. When such trusted platforms are used in applications, one of the key design issues is the ability to capture platform level requirements and to represent them as security policies for authorization decision making. This paper makes some contributions which we believe are an important first step in achieving policy based decision making with trusted platforms. It outlines a platform based trust management framework for specification of trust policies. In this context, we argue the need for a higher level abstraction that is able to capture the lower level state of the platform and use this in the evaluation of trust between the communicating entities. We extend the notion of trusted platform properties by introducing the concept of Component Property Certificates, which can be used in specifying and building trust relationships. We then illustrate how component property certificates can be used in the specification of trust policies of different granularities.5 page(s

Trust enhanced distributed authorisation for web services

In this paper, we propose a trust enhanced distributed authorisation architecture (TEDA) that provides a holistic framework for authorisation taking into account the state of a user platform. The model encompasses the notions of 'hard' and 'soft' trust to determine whether a platform can be trusted for authorisation. We first explain the rationale for the overall model and then describe our hybrid model with 'hard' and 'soft' trust components, followed by a description of the system architecture. We then illustrate our implementation of the proposed architecture in the context of authorisation for web services. We discuss the results and demonstrate that such a trust enhanced approach could enable better authorisation decision making, especially in a distributed environment where user platforms are subject to dynamic security threats.19 page(s

ALOPA: Authorization Logic for Property Attestation in trusted platforms

15 page(s

Trust management and negotiation for attestation in trusted platforms using web services

The concept of trusted computing technology is becoming significant in that such technologies are being increasingly available in PCs and mobile devices. With the advent of this technology, one can move from traditional user-only based trust management systems to user and platform-based trust management systems. In this paper, we propose a TCP based trust management and negotiation framework for better security decision making. In this regard, we outline a 3-stage property model that can be leveraged to define policies of different granularities. We then propose how Trust Policy Language (TPL) can be used to create compositions of properties. Finally, the paper discusses the different architectural design choices (such as push, pull and delegation based models) in negotiating trust using these policies and their implications in a distributed Web service based environment.8 page(s

Property based attestation and trusted computing : analysis and challenges

Trusted computing attestation mechanism relies on hash measurements to realize remote party attestation in distributed systems. Property based attestation enables more meaningful attestation by abstracting low level binary values to high level security properties or functions of systems. The contribution of this paper is two fold. In the first part of the paper, we provide an analysis of the different types of property based attestation mechanisms that have been proposed in the recent years. We categorize these mechanisms as derivation based, delegation based and enforcement based and analyze each of them with a particular focus on their limitations. In the second part, we provide a list of challenges for property based attestation. We believe this to be an useful exercise to help better understand the issues that limit the practical applicability of property based attestation in real world systems.8 page(s