Protocols de seguretat amb terceres parts

Les solucions proposades en els articles científics sobre els intercanvis electrònics entre dues parts sovint involucren terceres parts (TTPs) per resoldre i simplificar el problema, però els usuaris hi han de dipositar una certa confiança. Ara bé, la confiança no és garantia ferma del compliment dels requisits de seguretat. Per això, molts usuaris són reticents a dipositar confiança en entitats remotes, fet que en dificulta l’ús. Aquí mostram com, a partir d’un determinat protocol de seguretat, podem aconseguir que la TTP involucrada sigui verificable. Construïm un entorn de confiança dins del protocol per mitjà del subministrament d’evidències sobre cada una de les operacions de la TTP (definim i introduïm la verificabilitat on-line de la TTP). Aconseguim això gràcies a la detecció, l’anàlisi i la classificació de cada una de les accions de la TTP. Aportam unes orientacions de disseny que faciliten la introducció de TTPs verificables dins dels protocols

Fair exchange in e-commerce and certified e-mail, new scenarios and protocols

We are witnessing a steady growth in the use of Internet in the electronic commerce field. This rise is promoting the migration from traditional processes and applications (paper based) to an electronic model. But the security of electronic transactions continues to pose an impediment to its implementation. Traditionally, most business transactions were conducted in person. Signing a contract required the meeting of all interested parties, the postman delivered certified mail in hand, and when paying for goods or services both customer and provider were present. When all parties are physically present, a transaction does not require a complex protocol. The participants acknowledge the presence of the other parties as assurance that they will receive their parts, whether a signature on a contract, or a receipt, etc. But with e-commerce growing in importance as sales and business channel, all these transactions have moved to its digital counterpart. Therefore we have digital signature of contracts, certified delivery of messages and electronic payment systems. With electronic transactions, the physical presence is not required,moreover, most of the times it is even impossible. The participants in a transaction can be thousands of kilometers away from each other, and they may not even be human participants, they can be machines. Thus, the security that the transaction will be executed without incident is not assured per se, we need additional security measures. To address this problem, fair exchange protocols were developed. In a fair exchange every party involved has an item that wants to exchange, but none of the participants is willing to give his item away unless he has an assurance he will receive the corresponding item from the other participants. Fair exchange has many applications, like digital signature of contracts, where the items to be exchanged are signatures on contracts, certified delivery of messages, where we exchange a message for evidence of receipt, or a payment process, where we exchange a payment (e-cash, e-check, visa, etc.) for digital goods or a receipt. The objective of this dissertation is the study of the fair exchange problem. In particular, it presents two new scenarios for digital contracting, the Atomic Multi- Two Party (AM2P) and the Agent Mediated Scenario (AMS), and proposes one optimistic contract signing protocol for each one. Moreover, it studies the efficiency of Multi-Party Contract Signing (MPCS) protocols from their architecture point of view, presenting a new lower bound for each architecture, in terms of minimum number of transactions needed. Regarding Certified Electronic Mail (CEM), this dissertation presents two optimistic CEMprotocols designed to be deployed on thecurrent e-mail infrastructure, therefore they assume the participation of multiple Mail Transfer Agents (MTAs). In one case, the protocol assumes untrusted MTAs whereas in the other one it assumes each User Agent (UA) trusts his own MTA. Regarding payment systems, this dissertation presents a secure and efficient electronic bearer bank check scheme allowing the electronic checks to be transferred fairly and anonymously.L’ús d’Internet en l’àmbit del comerç electrònic està experimentant un creixement estable. Aquest increment d’ús està promovent lamigració de processos tradicionals i aplicacions (basades en paper) cap a un model electrònic. Però la seguretat de les transaccions electròniques continua impedint la seva implantació. Tradicionalment, la majoria de les transaccions s’han dut a terme en persona. La firma d’un contracte requeria la presència de tots els firmants, el carter entrega les cartes certificades enmà, i quan es paga per un bé o servei ambdós venedor i comprador hi són presents. Quan totes les parts hi són presents, les transaccions no requereixen un protocol complex. Els participants assumeixen la presència de les altres parts com assegurança que rebran el que esperen d’elles, ja sigui la firma d’un contracte, un rebut d’entrega o un pagament. Però amb el creixement del comerç electrònic com a canal de venda i negoci, totes aquestes transaccions s’hanmogut al seu equivalent en el món electrònic. Així doncs tenim firma electrònica de contractes, enviament certificat de missatges, sistemes de pagament electrònic, etc. En les transaccions electròniques la presència física no és necessària, de fet, la majoria de vegades és fins it tot impossible. Els participants poden estar separats permilers de kilòmetres, i no és necessari que siguin humans, podrien sermàquines. Llavors, la seguretat de que la transacció s’executarà correctament no està assegurada per se, necessitem proporcionar mesures de seguretat addicionals. Per solucionar aquest problema, es van desenvolupar els protocols d’intercanvi equitatiu. En un intercanvi equitatiu totes les parts involucrades tenen un objecte que volen intercanviar, però cap de les parts implicades vol donar el seu objecte si no té la seguretat que rebrà els objectes de les altres parts. L’intercanvi equitatiu té multitud d’aplicacions, com la firma electrònica de contractes, on els elements a intercanviar son firmes de contractes, enviament certificat demissatges, on s’intercanvien unmissatge per una evidència de recepció, o un procés de pagament, on intercanviemun pagament (e-cash, visa, e-xec, etc.) per bens digitals o per un rebut. L’objectiu d’aquesta tesi és estudiar el problema de l’intercanvi equitatiu. En particular, la tesi presenta dos nous escenaris per a la firma electrònica de contractes, l’escenari multi-two party atòmic i l’escenari amb agents intermediaris, i proposa un protocol optimista per a cada un d’ells. A més, presenta un estudi de l’eficiència dels protocols de firma electrònica multi-part (Multi-Party Contract Signing (MPCS) protocols) des del punt de vista de la seva arquitectura, presentant una nova fita per a cada una, en termes de mínim nombre de transaccions necessàries. Pel que fa al correu electrònic certificat, aquesta tesi presenta dos protocols optimistes dissenyats per a ser desplegats damunt l’infraestructura actual de correu electrònic, per tant assumeix la participació demúltiples agents de transferència de correu. Un dels protocols assumeix que cap dels agents de transferència de correu participants és de confiança,mentre que l’altre assumeix que cada usuari confia en el seu propi agent. Pel que fa a sistemes de pagament, la tesi presenta un esquema de xec bancari al portador, eficient i segur, que garanteix que la transferència dels xecs es fa demanera anònima i equitativa

A method for creating digital signature policies.

Increased political pressures towards a more efficient public sector have resulted in the increased proliferation of electronic documents and associated technologies such as Digital Signatures. Whilst Digital Signatures provide electronic document security functions, they do not confer legal meaning of a signature which captures the conditions under which a signature can be deemed to be legally valid. Whilst in the paper-world this information is often communicated implicitly, verbally or through notes within the document itself, in the electronic world a technological tool is required to communicate this meaning; one such technological aid is the Digital Signature Policy. In a transaction where the legality of a signature must be established, a Digital Signature Policy can confer the necessary contextual information that is required to make such a judgment. The Digital Signature Policy captures information such as the terms to which a signatory wishes to bind himself, the actual legal clauses and acts being invoked by the process of signing, the conditions under which a signatory's signature is deemed legally valid and other such information. As this is a relatively new technology, little literature exists on this topic. This research was conducted in an Action Research collaboration with a Spanish Public Sector organisation that sought to introduce Digital Signature Policy technology; their specific research problem was that the production of Digital Signature Policies was time consuming, resource intensive, arduous and suffered from lack of quality. The research therefore sought to develop a new and improved method for creating Digital Signature Policies. The researcher collaborated with the problem owner, as is typical of Participative Action Research. The research resulted in the development of a number of Information Systems artefacts, the development of a method for creating Digital Signature Policies and finally led to a stage where the problem owner could successfully develop the research further without the researcher's further input

Keeping Fairness Alive : Design and formal verification of optimistic fair exchange protocols

Fokkink, W.J. [Promotor]Pol, J.C. van de [Promotor

E-commerce protocol supporting automated online dispute resolution

E-commerce now constitutes a significant part of all commercial activity; however the increase in transactions is also leading to more disputes. These disputes are becoming more frequent, more technologically complicated and more difficult in terms of traceability . This thesis focuses specifically on dispute problems related to soft products, i.e. those that are intangible and therefore requiring no physical delivery. With the growing demand for these types of products, e.g. downloadable films, music, software, and prepaid calling time, the prevention of fraudulent transactions is becoming increasingly important. Reasons for the rise in the number of fraudulent transactions include merchants being unable to see the customer to verify an ID or signature and E-commerce enabling soft-products and services to be acquired via soft delivery methods: email, download or logging in. The introductory section provides a critique of current e-commerce fraud detection and prevention techniques and shows that not all are suitable for e-commerce, especially soft-products, and therefore unable to provide complete protection against fraud. The future relating to the detection and prevention of e-commerce fraud is then discussed, leading to suggestions regarding the improvement of the current state-of-the-art technique, the Address Verification Service (AVS), which is used to accommodate the introduction of soft-products. Apart from the exchange process problems, i.e. those involving money and goods, attention is also paid to other important factors such as timing and quality that are usually neglected in these detection and prevention techniques. Dispute scenarios from many different perspectives have been analysed, viz. computer science, business, legal and that of the participants themselves. From the analyses, all possible dispute cases have been formally listed using the 'Truth Table' approach. This analysis has then led to the design of a comprehensive taxonomy framework for dispute in e-commerce. The term Online Dispute Resolution (ODR), is the online technology applied to Alternative Dispute Resolution (ADR) which is resolving disputes other than via litigation in the courts. Current ODR systems and their suitability for the e-commercial world have been examined, concluding that not all are appropriate for e-commerce situations (since most still involve a human element and often make the resolution process more costly than the actual item under dispute). The proposed solution to the problem is by automating the online dispute resolution process. The total solution is described in two parts (i) an E-commerce Transaction Protocol (ETP) forming the infrastructure where the transaction will take place and be able to accommodate any new improvements in the future, and (ii) an Automated Online Dispute Resolution (AODR) system which should automatically resolve any dispute occurring within the proposed e-commerce model. In order for the AODR to resolve any dispute, a product/payment specific plug-in (add-on) has been incorporated into the system. For illustration purposes, credit cards as a payment method has been selected and the appropriate plug-in specification for soft products and credit cards created. The concept of providing every soft product with a quality certificate has also been discussed. A concluding case study of e-commerce in Saudi Arabia has been used to test the viability of both the e-commerce dispute taxonomy and the proposed model. The case study shows the suitability of using ETP with AODR in order to resolve soft-product disputes automatically. Limitations of the work and further research possibilities have then been identified.EThOS - Electronic Theses Online ServiceDepartment of Computing Science, Newcastle UniversityGBUnited Kingdo

Automating SLA enforcement in the cloud computing

Cloud computing is playing an increasingly important role, not only by facilitating digital trading platforms but also by transforming conventional services from client-server models to cloud computing. This domain has given the global economic and technological benefits, it offers to both the service providers and service subscribers. Digital marketplaces are no longer limited only to trade tangible commodities but also facilitates enormous service virtualization across various industries. Software as a Service (SaaS) being the largest service segment, dominates the global cloud migration. Infrastructure as a Service (IaaS) and cloud-based application development also known as Platform as a Service (PaaS) are also next-generation computing platforms for their ultimate futuristic demand by both, public and private sector. These service segments are now hosted on cloud platforms to compute, store, and network, an enormous amount of service requests, which process data incredibly fast and economically. Organizations also perform data analytics and other similar computing amenities to manage their business without maintaining on-premise computing infrastructures which are hard to maintain. This computing capability has extensively improved the popularity and increased the demand for cloud services to an extent, that businesses worldwide are heavily migrating their computing resources to these platforms. Diverse cloud service providers take the responsibility of provisioning such cloud-based services for subscribers. In return, a certain subscription fee is charged to them periodically and depending upon the service package, availability and security. On the flip side, such intensive technology shift and outsourcing reliance have also introduced scenarios that any failure on their part leads to serious consequences to the business community at large. In recent years technology industry has observed critical and increased service outages at various cloud service providers(CSP) such as Amazon AWS, Microsoft, Google, which ultimately interrupts the entire supply chain and causes several well-known web services to be taken offline either due to a human error, failed change control implementation or in more recently due to targeted cyber-attacks like DDoS. These web-based solutions such as compute, storage, network or other similar services are provisioned to cloud service subscribers (CSS) platforms. Regardless of a cloud service deployment, a legal binding such as a Service Level Agreement (SLA) is signed between the CSP and CSS. The SLA holds a service scope and guarantees in case of failure. There are probabilities where these SLA may be violated, revoked, or dishonoured by either party, mostly the CSP. An SLA violation along with an unsettled dispute leads to some financial losses for the service subscribers or perhaps cost them their business reputation. Eventually, the subscriber may request some form of compensation from the provider such as a service credit or a refund. In either case, the burden of proof lies with the subscribers, who have to capture and preserve those data or forensically sound system or service logs, supporting their claims. Most of the time, this is manually processed, which is both expensive and time-consuming. To address this problem, this research first analyses the gaps in existing arrangements. It then suggests automation of SLA enforcement within cloud environments and identifies the main properties of a solution to the problem covering various other avenues associated with the other operating environments. This research then subsequently proposes architectures, based on the concept of fair exchange, and shows that how intelligently the approach enforces cloud SLA using various techniques. Furthermore, by extending the research scope covering two key scenarios (a) when participants are loss averse and (b) when interacting participants can act maliciously. Our proposed architectures present robust schemes by enforcing the suggested solutions which are effective, efficient, and most importantly resilient to modern-day security and privacy challenges. The uniqueness of our research is that it does not only ensure the fairness aspect of digital trading but it also extends and logically implements a dual security layer throughout the service exchange. Using this approach protects business participants by securely automating the dispute resolutions in a more resilient fashion. It also shields their data privacy and security from diverse cyber challenges and other operational failures. These architectures are capable of imposing state-of-the-art defences through integrated secure modules along with full encryption schemes, mitigating security gaps previously not dealt with, based upon fair exchange protocols. The Protocol also accomplishes achieving service exchange scenarios either with or without dispute resolution. Finally, our proposed architectures are automated and interact with hardcoded procedures and verifications mechanism using a variant of trusted third parties and trusted authorities, which makes it difficult to cause potential disagreements and misbehaviours during a cloud-based service exchange by enforcing SLA

Practical Protocols for Certified Electronic Mail

Electronic mail, or e-mail, has brought us a big step closer towards the vision of paperless offices. To advance even closer to this vision, however, it is essential that existing e-mail systems be enhanced with value-added services which are capable of replacing many of the human procedures established in pen and paper communications. One of the most important and desirable such services is certified e-mail delivery, in which the intended recipient will get the mail content if and only if the mail originator receives an irrefutable proof-of-delivery from the recipient. In this paper, we present the design of two third-party based certified mail protocols, termed CMP1 and CMP2. Both protocols are designed for integration into existing standard e-mail systems and both satisfy the requirements of non-repudiation of origin, non-repudiation of delivery, and fairness. The difference between CMP1 and CMP2 is that the former provides no mail content confidentiality protection while the lat..

Practical protocols for certified electronic mail

Journal of Network and Systems Management43279-296JNSM