A Framework for Secure Group Key Management

The need for secure group communication is increasingly evident in a wide variety of governmental, commercial, and Internet communities. Secure group key management is concerned with the methods of issuing and distributing group keys, and the management of those keys over a period of time. To provide perfect secrecy, a central group key manager (GKM) has to perform group rekeying for every join or leave request. Fast rekeying is crucial to an application\u27s performance that has large group size, experiences frequent joins and leaves, or where the GKM is hosted by a group member. Examples of such applications are interactive military simulation, secure video and audio broadcasting, and secure peer-to-peer networks. Traditionally, the rekeying is performed periodically for the batch of requests accumulated during an inter-rekey period. The use of a logical key hierarchy (LKH) by a GKM has been introduced to provide scalable rekeying. If the GKM maintains a LKH of degree d and height h, such that the group size n ≤ dh, and the batch size is R requests, a rekeying requires the GKM to regenerate O(R × h) keys and to perform O(d × R × h) keys encryptions for the new keys distribution. The LKH approach provided a GKM rekeying cost that scales to the logarithm of the group size, however, the number of encryptions increases with increased LKH degree, LKH height, or the batch size. In this dissertation, we introduce a framework for scalable and efficient secure group key management that outperforms the original LKH approach. The framework has six components as follows. First, we present a software model for providing secure group key management that is independent of the application, the security mechanism, and the communication protocol. Second, we focus on a LKH-based GKM and introduce a secure key distribution technique, in which a rekeying requires the GKM to regenerate O( R × h) keys. Instead of encryption, we propose a novel XOR-based key distribution technique, namely XORBP, which performs an XOR operation between keys, and uses random byte patterns (BPs) to distribute the key material in the rekey message to guard against insider attacks. Our experiments show that the XORBP LKH approach substantially reduces a rekeying computation effort by more than 90%. Third, we propose two novel LKH batch rekeying protocols . The first protocol maintains a balanced LKH (B+-LKH) while the other maintains an unbalanced LKH (S-LKH). If a group experiences frequent leaves, keys are deleted form the LKH and maintaining a balanced LKH becomes crucial to the rekeying\u27s process performance. In our experiments, the use of a B+-LKH by a GKM, compared to a S-LKH, is shown to substantially reduce the number of LKH nodes (i.e., storage), and the number of regenerated keys per a rekeying by more than 50%. Moreover, the B +-LKH performance is shown to be bounded with increased group dynamics. Fourth, we introduce a generalized rekey policy that can be used to provide periodic rekeying as well as other versatile rekeying conditions. Fifth, to support distributed group key management, we identify four distributed group-rekeying protocols between a set of peer rekey agents. Finally, we discuss a group member and a GKM\u27s recovery after a short failure time

Key Management Systems for Smart Grid Advanced Metering Infrastructure: A Survey

Smart Grids are evolving as the next generation power systems that involve changes in the traditional ways of generation, transmission and distribution of power. Advanced Metering Infrastructure (AMI) is one of the key components in smart grids. An AMI comprises of systems and networks, that collects and analyzes data received from smart meters. In addition, AMI also provides intelligent management of various power-related applications and services based on the data collected from smart meters. Thus, AMI plays a significant role in the smooth functioning of smart grids. AMI is a privileged target for security attacks as it is made up of systems that are highly vulnerable to such attacks. Providing security to AMI is necessary as adversaries can cause potential damage against infrastructures and privacy in smart grid. One of the most effective and challenging topic's identified, is the Key Management System (KMS), for sustaining the security concerns in AMI. Therefore, KMS seeks to be a promising research area for future development of AMI. This survey work highlights the key security issues of advanced metering infrastructures and focuses on how key management techniques can be utilized for safeguarding AMI. First of all, we explore the main features of advanced metering infrastructures and identify the relationship between smart grid and AMI. Then, we introduce the security issues and challenges of AMI. We also provide a classification of the existing works in literature that deal with secure key management system in AMI. Finally, we identify possible future research directions of KMS in AMI

A practical key management and distribution system for IPTV conditional access

Conditional Access (CA) is widely used by pay-television operators to restrict access to content to authorised subscribers. Commercial CA solutions are available for structured broadcast and Internet Protocol Television (IPTV) environments, as well as Internet-based video-on-demand services, however these solutions are mostly proprietary, often inefficient for use on IP networks, and frequently depend on smartcards for maintaining security. An efficient, exible, and open conditional access system that can be implemented practically by operators with large numbers of subscribers would be beneficial to those operators and Set-Top-Box manufacturers in terms of cost savings for royalties and production costs. Furthermore, organisations such as the South African Broadcasting Corporation that are transitioning to Digital-Terrestrial-Television could use an open Conditional Access System (CAS) to restrict content to viewing within national borders and to ensure that only valid TV licence holders are able to access content. To this end, a system was developed that draws from the area of group key management. Users are grouped according to their subscription selections and these groups are authorised for each selection's constituent services. Group keys are updated with a key-tree based approach that includes a novel method for growing full trees that outperforms the standard method. The relations that are created between key trees are used to establish a hierarchy of keys which allows exible selection of services whilst maintaining their cryptographic protection. Conditions for security without dependence on smartcards are defined, and the system is expandable to multi-home viewing scenarios. A prototype implementation was used to assess the proposed system. Total memory consumption of the key-server, bandwidth usage for transmission of key updates, and client processing and storage of keys were all demonstrated to be highly scalable with number of subscribers and number of services

Sécurité dans les réseaux mobiles de nouvelle génération

RÉSUMÉ Les réseaux de nouvelle génération visent à converger les réseaux fixes et mobiles hétérogènes afin d’offrir tous les services à travers un réseau coeur tout IP. Faisant parti du réseau d’accès mobile, un des principaux objectifs du réseau 4G est de permettre une relève ininterrompue entre les réseaux cellulaires et WIFI pour ainsi favoriser l’apprivoisement de services vidéo mobiles exigeant des critères de qualité de service très stricts à moindres coûts. Cependant, l’uniformisation du trafic au niveau de la couche réseau favorise sa centralisation à travers un réseau coeur IP partagé par tous les opérateurs, la rendant ainsi comme une cible vulnérable de choix pour les pirates informatiques. La conception de solutions sécuritaires dans un environnement où les entités ne se connaissent pas à priori s’annonce comme une tâche très ardue. La thèse se penche sur quatre problématiques importantes dans les réseaux de nouvelle génération dont chacune est traitée dans un article distinct. Les deux premiers articles touchent à la sécurité dans un contexte décentralisé, à savoir les réseaux mobiles ad hoc (MANETs), alors que les deux derniers proposent des mécanismes innovateurs pour sécuriser des solutions visant à réduire la consommation de bande passante et d’énergie, en conformité avec le virage vert informatique promu par les opérateurs réseautiques. Plus précisément, le troisième article traite de la sécurisation des flots multicast dans un environnement à haut taux de perte de paquet et le dernier propose une solution d’optimisation de route sécuritaire pour mobile IPv6 (MIPv6) utilisant une version améliorée de l’algorithme de genération d’adresses cryptographiques (CGA) et les extensions de sécurité du système de nom de domaine (DNSSEC). Les systèmes de détection d’intrusion (IDS) pour les MANETs basés sur la réputation des noeuds classifient les participants du réseau selon leur degré de confiance. Cependant, ils partagent tous une vulnérabilité commune : l’impossibilité de détecter et de réagir aux attaques complices. Le premier article propose un IDS qui intègre efficacement le risque de collusion entre deux ou plusieurs noeuds malveillants dans le calcul de la fiabilité d’un chemin. L’algorithme propos´e ne se limite pas qu’au nombre et à la réputation des noeuds intermédiaires formant un chemin, mais intègre également d’autres informations pertinentes sur les voisins des noeuds intermédiaires d’un chemin pouvant superviser le message original et celui retransmis. Le IDS proposé détecte efficacement les noeuds malicieux et complices dans le but de les isoler rapidement du réseau. Les simulations lancées dans divers environnements MANETs contenant une proportion variable d’attaquants complices montrent bien l’efficacité du IDS proposée en offrant un gain en débit considérable comparativement aux solutions existantes. À l’instar de prévenir les comportements égoïstes des noeuds par la menace d’être privés de certaines fonctions, voire même isolés du réseau, due à une baisse de réputation, le second article opte pour un incitatif non-punitif en la monnaie virtuelle plus communément appelée nuglets. Plus précisément, l’article présente un cadre de travail issu de la théorie des jeux basé sur la compétition de Bertrand pour inciter les noeuds intermédiaires à retransmettre les messages selon les requis de QoS demandés par la source. Pour qu’un noeud source envoie ou accède à un flot sensible à la QoS comme par exemple les applications en temps réel, il débute par envoyer un contrat qui spécifie les critères de QoS, sa durée et son prix de réserve. Sur réception du contrat, les noeuds intermédiaires formant une route entre la source et la destination partagent les informations sur eux-mêmes et celles recueillies sur les noeuds voisins, anciens et courants pour estimer la probabilité de bris de contrat ainsi que le nombre de compétiteurs actifs. Ces deux paramètres sont cruciaux dans le processus de fixation des prix. Une fois les réponses de route recueillies, la source choisit la route la moins chère. Le cadre de travail multijoueur proposé, basé sur la compétition de Bertrand avec des firmes asymétriques et ayant accès à de l’information imparfaite, possède un équilibre de Nash en stratégies mixtes dans lequel le profit des firmes est positif et baisse non seulement avec le nombre de compétiteurs, mais aussi avec l’impression d’une précision accrue que les compétiteurs ont sur le coût de production du joueur. Les résultats montrent que l’incertitude sur les coûts augmente le taux de la marge brute et la fluctuation des prix tout en diminuant les chances d’honorer le contrat. Dans un autre ordre d’idée, l’intérêt sans cesse grandissant des opérateurs à converger les réseaux fixes et mobiles dans le but d’offrir une relève sans interruption favorise l’utilisation des applications vidéo mobiles qui surchargeront rapidement leurs réseaux. Dans un contexte du virage vert qui prend de plus en plus d’ampleur dans le domaine des télécommunications, la transmission des flots en multidiffusion (multicast) devient essentiel dans le but de réduire la consommation de bande passante et la congestion du réseau en rejoignant simultanément plusieurs destinataires. La sécurisation des flots en multidiffusion a été largement étudiée dans la littérature antérieure, cependant aucune des solutions proposées ne tient compte des contraintes imposées par les liaisons sans fil et la mobilité des noeuds, en particulier le haut taux de perte de paquets. La nécessité d’un mécanisme de distribution de clés régénératrices efficace et pouvant supporter un grand bassin d’abonnés pour les réseaux mobiles n’aura jamais été aussi urgent avec l’arrivée de la convergence fixe-mobile dans les réseaux 4G. Le troisième article présente deux algorithmes de clés régénératrices basés sur les chaînes de hachage bidirectionnelles pour le protocole de distribution de clés logical key hierarchy (LKH). Ainsi, un membre ayant perdu jusqu’à un certain nombre de clés de déchiffrement consécutives pourrait lui-même les régénérer sans faire la requête de retransmission au serveur de clés. Les simulations effectuées montrent que les algorithmes proposés offrent des améliorations considérables dans un environnement de réseau mobile à taux de perte de paquet, notamment dans le percentage de messages déchiffrés. Le souci d’efficacité énergétique est également présent pour les opérateurs de réseaux cellulaires. D’ailleurs, près de la moitié des abonnements sur Internet proviennent présentement d’unités mobiles et il est attendu que ce groupe d’utilisateurs deviennent le plus grand bassin d’usagers sur Internet dans la prochaine décennie. Pour supporter cette croissance rapide du nombre d’utilisateurs mobiles, le choix le plus naturel pour les opérateurs serait de remplacer mobile IPv4 par MIPv6. Or, la fonction d’optimisation de route (RO), qui remplace le routage triangulaire inefficace de MIP en permettant au noeud mobile (MN) une communication bidirectionnelle avec le noeud correspondant (CN) sans faire passer les messages à travers l’agent du réseau mère (HA), est déficiente au niveau de la sécurité. L’absence d’informations pré-partagées entre le MN et le CN rend la sécurisation du RO un défi de taille. MIPv6 adopte la routabilité de retour (RR) qui est davantage un mécanisme qui vérifie l’accessibilité du MN sur son adresse du réseau mère (HoA) et du réseau visité (CoA) plutôt qu’une fonction de sécurité. D’autres travaux se sont attaqués aux nombreuses failles de sécurité du RR, mais soit leur conception est fautive, soit leurs suppositions sont irréalistes. Le quatrième article présente une version améliorée de l’algorithme de génération cryptographique d’adresse (ECGA) pour MIPv6 qui intègre une chaîne de hachage arrière et offre de lier plusieurs adresses CGA ensemble. ECGA élimine les attaques de compromis temps-mémoire tout en étant efficace. Ce mécanisme de génération d’adresse fait parti du protocole Secure MIPv6 (SMIPv6) proposé avec un RO sécuritaire et efficace grâce à DNSSEC pour valider les CGAs qui proviennent d’un domaine de confiance et qui permet une authentification forte plutôt que l’invariance de source. Le vérificateur de protocoles cryptographiques dans le modèle formel AVISPA a été utilisé pour montrer qu’aucune faille de sécurité n’est présente tout en limitant au maximum les messages échangés dans le réseau d’accès. ----------ABSTRACT Next generation networks aim at offering all available services through an IP-core network by converging fixed-mobile heterogeneous networks. As part of the mobile access network, one of the main objectives of the 4G network is to provide seamless roaming with wireless local area networks and accommodating quality of service (QoS) specifications for digital video broadcasting systems. Such innovation aims expanding video-based digital services while reducing costs by normalizing the network layer through an all-IP architecture such as Internet. However, centralizing all traffic makes the shared core network a vulnerable target for attackers. Design security solutions in such an environment where entities a priori do not know each other represent a daunting task. This thesis tackles four important security issues in next generation networks each in distinct papers. The first two deal with security in decentralized mobile ad hoc networks (MANETs) while the last two focus on securing solutions aiming at reducing bandwidth and energy consumption, in line with the green shift promoted by network operators. More precisely, the third paper is about protecting multicast flows in a packet-loss environment and the last one proposes a secure route optimization function in mobile IPv6 (MIPv6) using an enhanced version of cryptographically generated address (CGA) and domain name service security extensions (DNSSEC). Most intrusion detection systems (IDS) for MANETs are based on reputation system which classifies nodes according to their degree of trust. However, existing IDS all share the same major weakness: the failure to detect and react on colluding attacks. The first paper proposes an IDS that integrates the colluding risk factor into the computation of the path reliability which considers the number and the reputation of nodes that can compare both the source message and the retransmitted one. Also, the extended architecture effectively detects malicious and colluding nodes in order to isolate them and protect the network. The simulations launched in various MANETs containing various proportions of malicious and colluding nodes show that the proposed solution offers a considerable throughput gain compared to current solutions. By effectively selecting the most reliable route and by promptly detecting colluding attacks, the number of lost messages is decreased, and therefore, offering more efficient transmissions. Instead of thwarting selfishness in MANETs by threatening nodes to limit their network functions, the second paper opts for a non-punishment incentive by compensating nodes for their service through the use of virtual money, more commonly known as nuglets. The last paper presents a game-theoretic framework based on Bertrand competition to incite relaying nodes in forwarding messages according to QoS requirements. For a source to send or access QoS-sensitive flows, such as real-time applications, it starts by sending a contract specifying the QoS requirements, its duration and a reservation price. Upon receiving a contract submission, intermediary nodes forming a route between the source and the destination share their current and past collected information on themselves and on surrounding nodes to estimate the probability of breaching the contract and the number of active competitors. Both parameters are crucial in setting a price. Once the source gets the responses from various routes, it selects the most cheapest one. This multiplayer winner-takes-all framework based on Bertrand competition with firms having asymmetric costs and access imperfect information has a mixed-strategy equilibrium in which industry profits are positive and decline not only with the number of firms having an estimated cost below the reservation price but also with the perception of a greater accuracy on a player’s cost that competitors have. In fact,results show that cost uncertainty increases firms’ gross margin rate and the prices fluctuation while making the contract honoring much riskier. On another topic, with the growing interest in converging fixed and mobile networks, mobile applications will require more and more resources from both the network and the mobile device. In a social-motivated context of shifting into green technologies, using multicast transmissions is essential because it lowers bandwidth consumption by simultaneously reaching a group of multiple recipients. Securing multicast flows has been extensively studied in the past, but none of the existing solutions were meant to handle the constraints imposed by mobile scenarios, in particular the high packet-loss rate. The need for a low overhead selfhealing rekeying mechanism that is scalable, reliable and suitable for mobile environments has never been more urgent than with the arrival of fixed-mobile convergence in 4G networks. The second paper presents two self-healing recovery schemes based on the dual directional hash chains for the logical key hierarchy rekeying protocol. This enables a member that has missed up to m consecutive key updates to recover the missing decryption keys without asking the group controller key server for retransmission. Conducted simulations show considerable improvements in the ratio of decrypted messages and in the rekey message overhead in high packet loss environments. The concern of energy efficiency is also present for mobile access network operators. In fact, nearly half of all Internet subscribers come from mobile units at the moment and it is expected to be the largest pool of Internet users by the next decade. The most obvious choice for mobile operators to support more users would be to replace Mobile IP for IPv4 with MIPv6. However, the Route Optimization (RO) function, which replaces the inefficient triangle routing by allowing a bidirectional communication between a mobile node (MN) and the corresponding node (CN) without passing through its home agent (HA), is not secure and has a high overhead. The lack of pre-shared information between the MN and the CN makes security in RO a difficult challenge. MIPv6 adopts the return routability (RR) mechanism which is more to verify the MN reachability in both its home address (HoA) and care-of address (CoA) than a security feature. Other works attempted to solve the multiple security issues in RR but either their design are flawed, or rely on unrealistic assumptions. The third paper presents an enhanced cryptographically generated address (ECGA) for MIPv6 that integrates a built-in backward key chain and offers support to bind multiple logically-linked CGAs together. ECGA tackles the time-memory tradeoff attacks while being very efficient. It is part of the proposed secure MIPv6 (SMIPv6) with secure and efficient RO which uses DNSSEC to validate CGAs from trusted domains and provide strong authentication rather than sender invariance. The AVISPA on-the-fly model checker (OFMC) tool has been used to show that the proposed solution has no security flaws while still being lightweight in signalling messages in the radio network

Security in Distributed, Grid, Mobile, and Pervasive Computing

This book addresses the increasing demand to guarantee privacy, integrity, and availability of resources in networks and distributed systems. It first reviews security issues and challenges in content distribution networks, describes key agreement protocols based on the Diffie-Hellman key exchange and key management protocols for complex distributed systems like the Internet, and discusses securing design patterns for distributed systems. The next section focuses on security in mobile computing and wireless networks. After a section on grid computing security, the book presents an overview of security solutions for pervasive healthcare systems and surveys wireless sensor network security

Journal of Telecommunications and Information Technology, 2017, nr 1

kwartalni

Sixth International Joint Conference on Electronic Voting E-Vote-ID 2021. 5-8 October 2021

This volume contains papers presented at E-Vote-ID 2021, the Sixth International Joint Conference on Electronic Voting, held during October 5-8, 2021. Due to the extraordinary situation provoked by Covid-19 Pandemic, the conference is held online for second consecutive edition, instead of in the traditional venue in Bregenz, Austria. E-Vote-ID Conference resulted from the merging of EVOTE and Vote-ID and counting up to 17 years since the _rst E-Vote conference in Austria. Since that conference in 2004, over 1000 experts have attended the venue, including scholars, practitioners, authorities, electoral managers, vendors, and PhD Students. The conference collected the most relevant debates on the development of Electronic Voting, from aspects relating to security and usability through to practical experiences and applications of voting systems, also including legal, social or political aspects, amongst others; turning out to be an important global referent in relation to this issue. Also, this year, the conference consisted of: · Security, Usability and Technical Issues Track · Administrative, Legal, Political and Social Issues Track · Election and Practical Experiences Track · PhD Colloquium, Poster and Demo Session on the day before the conference E-VOTE-ID 2021 received 49 submissions, being, each of them, reviewed by 3 to 5 program committee members, using a double blind review process. As a result, 27 papers were accepted for its presentation in the conference. The selected papers cover a wide range of topics connected with electronic voting, including experiences and revisions of the real uses of E-voting systems and corresponding processes in elections. We would also like to thank the German Informatics Society (Gesellschaft für Informatik) with its ECOM working group and KASTEL for their partnership over many years. Further we would like to thank the Swiss Federal Chancellery and the Regional Government of Vorarlberg for their kind support. EVote- ID 2021 conference is kindly supported through European Union's Horizon 2020 projects ECEPS (grant agreement 857622) and mGov4EU (grant agreement 959072). Special thanks go to the members of the international program committee for their hard work in reviewing, discussing, and shepherding papers. They ensured the high quality of these proceedings with their knowledge and experience

Electronic Voting: 6th International Joint Conference, E-Vote-ID 2021, Virtual Event, October 5–8, 2021: proceedings

This volume contains the papers presented at E-Vote-ID 2021, the Sixth International Joint Conference on Electronic Voting, held during October 5–8, 2021. Due to the extraordinary situation brought about by the COVID-19, the conference was held online for the second consecutive edition, instead of in the traditional venue in Bregenz, Austria. The E-Vote-ID conference is the result of the merger of the EVOTE and Vote-ID conferences, with first EVOTE conference taking place 17 years ago in Austria. Since that conference in 2004, over 1000 experts have attended the venue, including scholars, practitioners, authorities, electoral managers, vendors, and PhD students. The conference focuses on the most relevant debates on the development of electronic voting, from aspects relating to security and usability through to practical experiences and applications of voting systems, also including legal, social, or political aspects, amongst others, and has turned out to be an important global referent in relation to this issue

Examining organisational flexibility in an interorganisational context: A case study of a grocery retail supply chain.

The objective of this thesis is to clarify the complex notion of flexibility and to explore the impact of Interorganisational Information Systems (IOS) on the flexibility of organisations. Previous studies have shown that while the utilisation of IOS can contribute significantly to organisational flexibility, it does not provide equal benefits to all trading partners. Although flexibility is increasingly becoming more important for the survivability and competitiveness of organisations, its meaning is still ambiguous and a rigorous conceptualisation of the notion is lacking in the literature. Most researchers examining the impact of technology on organisational flexibility identify technological as well as organisational issues influencing flexibility, but fail to analyse flexibility as a dynamic concept embedded in the social context. Moreover, they mainly focus on the flexibility of the individual firm, paying less attention to flexibility as a property of the interaction between firms. This research proposes an interpretive approach and examines the notion of flexibility by including a thorough investigation of the organisational context within which it is embedded. Since IOS involve interaction between different organisations, issues of cooperation and relationships with trading partners are also considered. Therefore, the concept of flexibility is viewed from both an organisational and an interorganisational (business network) level, referring to the interaction of trading partners. A synthesized research framework, based on previous research and the theoretical perspectives of appreciative systems thinking and web models, enables us to perceive flexibility as a multidimensional and dynamic concept, embedded in and shaped by the organisational/interorganisational context. In the proposed framework, flexibility is presented not only as the ability of the organisation/business network to respond to environmental disturbances, but also as its capability to evolve and to change over time. A multiple case design in a grocery retail-supply chain in Greece, comprising three suppliers and four retailers, provides the empirical data to support the argument of this thesis. The analysis of the data relates differences in organisational contexts to variations in the flexibility achieved by the organisations. It shows that IOS can provide constraints even for the more competent organisations and illustrates how the interaction with trading partners may influence the flexibility achieved at an organisational level. It finally demonstrates the dynamic nature of flexibility, it describes the relation between its different dimensions and discusses their change and evolution, following and influencing the changes of the organisational and interorganisational contexts

'They are Exactly as Bank Notes are': Perceptions and Technologies of Bank Note Forgery During the Bank Restriction Period, 1797 - 1821

Previous studies of Bank Note forgery in England during the Bank Restriction Period have adopted a highly institutional focus. Thus, much is known about the role played by both the Bank of England and the workings of the criminal justice system in combating both forgers and forged note utterers. The question of how the new system of small denomination Bank Notes impacted upon the day to day lives and understandings of the people that used them has received far less attention. The actual means by which Bank Notes were themselves forged has also been overlooked. This has led to a somewhat two-dimensional view of these notes as material objects. This thesis will engage with common mentalities and perceptions, seeking to write a 'new history from below' of both Bank Notes and their forgery in this period. Its primary aims will be to explore the question of why the English people were so easily imposed upon by forged Bank Notes; the various means by which forged notes could be constructed; and what an analysis of both of these points can tell us about economic and social understandings of non-elite people at this time. It will be argued that by studying instances in which small denomination Bank Notes were routinely exchanged, we can highlight a significant dichotomy of understanding in a society that was starting to engage with a new culture of promise based fiduciary paper money, yet was still deeply rooted in early-modern notions of paper instruments as objects of personal credit and debt. The thesis will show that heavy exposure to Bank Notes at this time clearly equipped some contemporaries with their own personalised sets of aesthetic and material "standards", against which the "goodness" of any monetary instrument with which they were presented would be compared. Others continued to examine the material aspect of Bank Notes via a direct comparison or consultation with others. Neither approach was always successful and indeed whatever method was adopted, the common occurrence of the materials and technologies required to construct a credible imitation of a Bank Note meant that it was not just illiterate persons that were susceptible to being deceived. Even a reading of the Bank Note's literate text failed to provide sufficient defence against the activities of the forger