Middleware support for non-repudiable business-to-business interactions

The wide variety of services and resources available over the Internet presents new opportunities for organisations to collaborate to reach common goals. For example, business partners wish to access each other’s services and share information along the supply chain in order to compete more successfully in the delivery of goods or services to the ultimate customer. This can lead to the investment of significant resources by business partners in the resulting collaboration. In the context of such high value business-to-business (B2B) interactions it is desirable to regulate (monitor and control) the behaviour of business partners to ensure that they comply with agreements that govern their interactions. Achieving this regulation is challenging because, while wishing to collaborate, organisations remain autonomous and may not unguardedly trust each other. Two aspects must be addressed: (i) the need for high-level mechanisms to encode agreements (contracts) between the interacting parties such that they can be used for run-time monitoring and enforcement, and (ii) systematic support to monitor a given interaction for conformance with contract and to ensure accountability. This dissertation concerns the latter aspect — the definition, design and implementation of underlying middleware support for the regulation of B2B interactions. To this end, two non-repudiation services are identified — non-repudiable service invocation and non-repudiable information sharing. A flexible nonrepudiation protocol execution framework supports the delivery of the identified services. It is shown how the services can be used to regulate B2B interactions. The non-repudiation services provide for the accountability of the actions of participants; including the acknowledgement of actions, their run-time validation with respect to application-level constraints and logging for audit. The framework is realised in the context of interactions with and between components of a J2EE application server platform. However, the design is sufficiently flexible to apply to other common middleware platforms.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Enhancing the reliability of digital signatures as non-repudiation evidence under a holistic threat model

Traditional sensitive operations, like banking transactions, purchase processes, contract agreements etc. need to tie down the involved parties respecting the commitments made, avoiding a further repudiation of the responsibilities taken. Depending on the context, the commitment is made in one way or another, being handwritten signatures possibly the most common mechanism ever used. With the shift to digital communications, the same guarantees that exist in real world transactions are expected from electronic ones as well. Non-repudiation is thus a desired property of current electronic transactions, like those carried out in Internet banking, e-commerce or, in general, any electronic data interchange scenario. Digital evidence is generated, collected, maintained, made available and verified by non-repudiation services in order to resolve disputes about the occurrence of a certain event, protecting the parties involved in a transaction against the other's false denial about such an event. In particular, a digital signature is considered as non-repudiation evidence which can be used subsequently, by disputing parties or by an adjudicator, to arbitrate in disputes. The reliability of a digital signature should determine its capability to be used as valid evidence. The reliability depends on the trustworthiness of the whole life cycle of the signature, including the generation, transfer, verification and storage phases. Any vulnerability in it would undermine the reliability of the digital signature, making its applicability as non-repudiation evidence dificult to achieve. Unfortunately, technology is subject to vulnerabilities, always with the risk of an occurrence of security threats. Despite that, no rigorous mechanism addressing the reliability of digital signatures technology has been proposed so far. The main goal of this doctoral thesis is to enhance the reliability of digital signatures in order to enforce their non-repudiation property when acting as evidence. In the first instance, we have determined that current technology does not provide an acceptable level of trustworthiness to produce reliable nonrepudiation evidence that is based on digital signatures. The security threats suffered by current technology are suffice to prevent the applicability of digital signatures as non-repudiation evidence. This finding is also aggravated by the fact that digital signatures are granted legal effectiveness under current legislation, acting as evidence in legal proceedings regarding the commitment made by a signatory in the signed document. In our opinion, the security threats that subvert the reliability of digital signatures had to be formalized and categorized. For that purpose, a holistic taxonomy of potential attacks on digital signatures has been devised, allowing their systematic and rigorous classification. In addition, and assuming a realistic security risk, we have built a new approach more robust and trustworthy than the predecessors to enhance the reliability of digital signatures, enforcing their non-repudiation property. This new approach is supported by two novel mechanisms presented in this thesis: the signature environment division paradigm and the extended electronic signature policies. Finally, we have designed a new fair exchange protocol that makes use of our proposal, demonstrating the applicability in a concrete scenario. ----------------------------------------------------------------------------------------------------------------------------------------------------------------Las operaciones sensibles tradicionales, tales como transacciones bancarias, procesos de compra-venta, firma de contratos etc. necesitan que las partes implicadas queden sujetas a los compromisos realizados, evitando así un repudio posterior de las responsabilidades adquiridas. Dependiendo del contexto, el compromiso se llevaría a cabo de una manera u otra, siendo posiblemente la firma manuscrita el mecanismo más comúnmente empleado hasta la actualidad. Con el paso a las comunicaciones digitales, se espera que las mismas garantías que se encuentran en las transacciones tradicionales se proporcionen también en las electrónicas. El no repudio es, por tanto, una propiedad deseada a las actuales transacciones electrónicas, como aquellas que se llevan a cabo en la banca online, en el comercio electrónico o, en general, en cualquier intercambio de datos electrónico. La evidencia digital se genera, recoge, mantiene, publica y verifica mediante los servicios de no repudio con el fin de resolver disputas acerca de la ocurrencia de un determinado evento, protegiendo a las partes implicadas en una transacción frente al rechazo respecto a dicho evento que pudiera realizar cualquiera de las partes. En particular, una firma digital se considera una evidencia de no repudio que puede emplearse posteriormente por las partes enfrentadas o un tercero durante el arbitrio de la disputa. La fiabilidad de una firma digital debería determinar su capacidad para ser usada como evidencia válida. Dicha fiabilidad depende de la seguridad del ciclo de vida completo de la firma, incluyendo las fases de generación, transferencia, verificación, almacenamiento y custodia. Cualquier vulnerabilidad en dicho proceso podría socavar la fiabilidad de la firma digital, haciendo difícil su aplicación como evidencia de no repudio. Desafortunadamente, la tecnología está sujeta a vulnerabilidades, existiendo siempre una probabilidad no nula de ocurrencia de amenazas a su seguridad. A pesar de ello, hasta la fecha no se ha propuesto ningún mecanismo que aborde de manera rigurosa el estudio de la fiabilidad real de la tecnología de firma digital. El principal objetivo de esta tesis doctoral es mejorar la fiabilidad de las firmas digitales para que éstas puedan actuar como evidencia de no repudio con garantías suficientes

I Did Not Accept That: Demonstrating Consent in Online Collection of Personal Data

Privacy in online collection of personal data is currently a much debated topic considering, amongst other reasons, the incidents with well known digital organisations, such as social networks and, in Europe, the recent EU/GDPR regulation. Among other required practices, explicit and simply worded consent from individuals must be obtained before collecting and using personal information. Further, individuals must also be given detailed information about what, how and what for data is collected. Consent is typically obtained at the collection point and, at a single point in time (ignoring updates), associated with Privacy Policies or End-User Agreements. At any moment, both the user and the organization should be able to produce evidence of this consent. This proof should not be disputable which leads us to strong cryptographic properties. The problem we discuss is how to robustly demonstrate such consent was given. We adapt fair-exchange protocols to this particular problem and, upon an exchange of personal data, we are able to produce a cryptographic receipt of acceptance that any party can use to prove consent and elicit non-repudiation. We discuss two broad strategies: a pure peerto-peer scheme and the use of a Trusted Third Party