Stuttgart, Univ., Studienarb., 2003.

Vem vill inte vara sig själv [Who Doesn't to be Himself]  opens a discussion on the meaning and function of the alter ego in contemporary culture. In the essay the writer goes back and forth between describing and analyzing the examples he presents, mainly subcultural and media influenced facts and phenomena, and here and there he connects them to personal experiences, among other things the part the alter ego played in his first meeting with art.

Internet users generally feel their actions are anonymous, but this is often not the case. Users can be tracked and their actions logged for future analysis, which is not the desire of most users. Software and services exist which offer anonymity on the Internet when used correctly. Anonymity on the Internet is useful for many people including whistleblowers, dissidents, law enforcement, and the security conscious, but it can be abused. A user can act maliciously under the guise of anonymity without the fear of retribution. Thus, a level of administrative control over users is desirable, even in an anonymous system. Administrative control over users in an open, anonymous system is extremely difficult, but what about a closed, pseudonymous system? Closed Pseudonymous Groups is a pseudonymous framework for a closed group of users that balances the needs of the user with those of a service administrator. Using a resource that uniquely identifies a user, the user may create a pseudonym with which they can interact with the service over the Internet. Misbehaving pseudonyms can be blocked from using the service, and the offending user is unable to create a new authorized pseudonym.

Security is a necessity when dealing with new forms of technology that may not have been analyzed from a security perspective. One of the latest growing technological advances are Vehicular Ad-Hoc Networks (VANETs). VANETs allow vehicles to communicate information to each other wirelessly which allows for an increase in safety and efficiency for vehicles. However, with this new type of computerized system comes the need to maintain security on top of it. In order to try to protect location privacy of the vehicles in the system, vehicles change pseudonyms or identifiers at areas known as mix zones. This thesis implements a model that characterizes the attack surface of an adversarial insider vehicle inside of a VANET. This adversarial vehicle model describes the interactions and effects that an attacker vehicle can have on mix zones in order to lower the overall location privacy of the system and remain undetected to defenders in the network. In order to reach the final simulation of the model, several underlying models had to be developed around the interactions of defender and attacker vehicles. The evaluation of this model shows that there are significant impacts that internal attacker vehicles can have on location privacy within mix zones. From the created simulations, the results show that having one to five optimal attackers shows a decrease of 0.6%-2.6% on the location privacy of the network and a 12% decrease in potential location privacy in a mix zone where an attacker defects in a 50-node network. The industry needs to consider implementing defenses based on this particular attack surface discussed.

This diploma thesis is examining hidden presence of a French author Romain Gary in the works of Émile Ajar. Only after Gary's death the public learned, that Émile Ajar was in fact Gary's pseudonym, although he has publicly denied this connection throughout his life. Because of this unrevealed mystification, Gary was given Goncourt prize twice, despite the fact that each author is only allowed to receive it once. Gary claims in his testament, that an observant reader of his work should immediately discover the connection. Can we agree with him, even if literary critics failed to find out? This work investigates various literary practices used by authors to hide their identity. The "lives" of both authors are presented. Gary did not only create Émile Ajar's life story, he also persuaded his nephew to pose as Ajar in public. The stories are followed by a comparative analysis of eight novels: four published under Gary's name and four under the pseudonym. Comparing the selected works from diverse aspects, we try to answer the principal question: Was it possible to prove that Émile Ajar was Gary's creation during his very lifetime?

The idea of vehicular communication systems could bring more safety, immunity and assurance in driving while it poses a variety of applications in traffic efficiency, driver assistance, environmental hazards, road conditions and infotainment. The aim is to make driving safer and to facilitate driving to the full extent, even on dangerous roads. However, having effective and robust operations within the VC system needs an infrastructure to handle threats, faults, illegitimate activities and unexpected incidents. Message authentication, integrity, non-repudiation and privacy within such a system are considered as the most controversial issues from security perspective. The idea is to protect privacy not only from legal point of view, but also from technical perspective in terms of using privacy enhancing technologies. To provide security within such a system, the idea of Public Key Infrastructure is considered as a promising solution. Using long-term certificates does reveal the real identity of the owner. Since users’ privacy is considered as the main security requirement in the VC system, standard certificates (X.509) and normal PKI cannot be used within a VC network. There are some functionalities and features for vehicular communication systems that do not exist in standard PKI. As a result, using pseudonym certificates to perform transactions within the VC system is a solution. In this report, a vehicular public key infrastructure, called VPKI, is proposed. OpenCA is used as the PKI, equipped with Pseudonym Certificate Authority (PCA), Long-Term Certificate Authority (LTCA) and Pseudonym Resolution Authority (PRA). These authorities are certified by the RCA and they have privileges to perform their tasks. LTCA is responsible for issuing long-term certificates while PCA is responsible for issuing pseudonym certificates. PRA is the authority to perform pseudonym resolution to identify the real identity of a pseudonym certificate. When it comes to CRL, PCA is the responsible authority to determine revoked pseudonym certificates in order to keep the system secure. Three protocols are then proposed to obtain pseudonym certificates, latest version of pseudonym CRL as well as performing pseudonym resolution. Obtaining pseudonym certificates is done in two phases. Firstly, each vehicle sends a request to LTCA to get a valid token. In the second step, the token is used by PCA to issue pseudonym certificates.

Abstract Vehicular Ad Hoc Networks (VANET) can provide strong safety for vehicles by taking the advantages of the information which are interchanged among themselves and some infrastructures. Due to this significant application of VANET, message authentication and privacy in VANET is quite critical. Pseudonym PKI technology is a practical solution to ensure the above two properties. However, the performance of the previous works cannot satisfy the requirement for the applications in VANET, such as efficiency and management cost. Most of all pseudonym PKI technologies are comprehensive schemes, like group key and ID-based public key cryptosystem. This also increases the implementation complexity of VANET security. Therefore, we will propose an efficient pseudonym PKI mechanism based on bilinear mapping to improve the performance of the message authentication protocol, certificate tracing and certificate revocation, implementation cost, and management cost.

Efforts towards standardization of Vehicular Communication Systems (VCSs) have been conclusive on the use of Vehicular Public-Key Infrastructure (VPKI) for the establishment of trust among network participants. Employing VPKI in Vehicular Communication (VC) guarantees the integrity and authenticity of Cooperative Awareness Messages (CAMs) and Decentralized Environmental Notification Messages (DENMs). It also offers a level of privacy for vehicles as VPKI provides them with a set of non-linkable short-lived certificates, called pseudonyms, which are used to sign outgoing messages by vehicles while they communicate with other vehicles referred to as Vehicle-to-Vehicle (V2V) or Roadside Units (RSUs) referred to as Vehicle-to-Infrastructure (V2I). Each vehicle uses a pseudonym for its lifetime and by switching to a not- previously- used pseudonym, it continues to communicate without risking its privacy. There have been two approaches suggested by the literature on how to provide vehicles with pseudonyms. One is the so-called pre-loading mode, suggesting to pre-load vehicles with all pseudonyms they need, which increases the cost of revocation in case they are compromised. The other one is the on-demand mode, suggesting a real-time offering of pseudonyms by VPKI at vehicles request e.g., on starting each trip. Choosing the on-demand approach imposes a considerable burden of availability and resilience on VPKI services. In this work, we are confronting the problems regarding a large-scale deployment of an on-demand VPKI that is resilient, highly available, and dynamically scalable. In order to achieve that, by leveraging state-of-the-art tools and design paradigms, we have enhanced a VPKI system to ensure that it is capable of meeting enterprise-grade Service Level Agreement (SLA) in terms of availability, and it can also be cost-efficient as services can dynamically scale-out in the presence of high load, or possibly scale-in when facing less demand. That has been made possible by re-architecting and refactoring an existing VPKI into a cloud-native solution deployed as microservices. Towards having a reliable architecture based on distributed microservices, one of the key challenges to deal with is Sybil-based misbehavior. By exploiting Sybil-based attacks in VPKI, malicious vehicles can gain influential advantage in the system, e.g., one can affect the traffic to serve its own will. Therefore, preventing the occurrence of Sybil attacks is paramount. On the other hand, traditional approaches to stop them, often come with a performance penalty as they verify requests against a relational database which is a bottleneck of the operations. We propose a solution to address Sybil-based attacks, utilizing Redis, an in-memory data store, without compromising the system efficiency and performance considerably. Running our VPKI services on Google Cloud Platform (GCP) shows that a large-scale deployment of VPKI as a Service (VPKIaaS) can be done efficiently. Conducting various stress tests against the services indicates that the VPKIaaS is capable of serving real world traffic. We have tested VPKIaaS under synthetically generated normal traffic flow and flash crowd scenarios. It has been shown that VPKIaaS managed to issue 100 pseudonyms per request, submitted by 1000 vehicles where vehicles kept asking for a new set of pseudonyms every 1 to 5 seconds. Each vehicle has been served in less than 77 milliseconds. We also demonstrate that, under a flash crowd situation, with 50000 vehicles, VPKIaaS dynamically scales out, and takes ≈192 milliseconds to serve 100 pseudonyms per request submitted by vehicles. / Ansträngningar för standardisering av Vehicular Communication Systems har varit avgörande för användandet av Vehicular Public-Key Infrastructure (VPKI) för att etablera förtroende mellan nätverksdeltagare. Användande av VPKI i Vehicular Communication (VC) garanterar integritet och autenticitet av meddelanden. Det erbjuder ett lager av säkerhet för fordon då VPKI ger dem en mängd av icke länkbara certifikat, kallade pseudonym, som används medan de kommunicerar med andra fordon, kallat Vehicle-to-Vehicle (V2V) eller Roadside Units (RSUs) kallat Vehicle-to-Infrastructure (V2I). Varje fordon använder ett pseudonym under en begränsad tid och genom att byta till ett icke tidigare använt pseudonym kan det fortsätta kommunicera utan att riskera sin integritet. I litteratur har två metoder föreslagits för hur man ska ladda fordon med pseudonym de behöver. Den ena metoden det så kallade offline-läget, som proponerar att man för-laddar fordonen med alla pseudonym som det behöver vilket ökar kostnaden för revokering i fall de blir komprometterat. Den andra metoden föreslår ett on-demand tillvägagångssätt som erbjuder pseudonym via VPKI på fordonets begäran vid början av varje färd. Valet av på begäran metoden sätter en stor börda på tillgänglighet och motståndskraft av VPKI tjänster. I det här arbetet, möter vi problem med storskaliga driftsättningar av en på begäran VPKI som är motståndskraftig, har hög tillgänglighet och dynamiskt skalbarhet i syfte att uppnå dessa attribut genom att nyttja toppmoderna verktyg och designparadigmer. Vi har förbättrat ett VPKI system för att säkerställa att det är kapabelt att möta SLA:er av företagsklass gällande tillgänglighet och att det även kan vara kostnadseffektivt eftersom tjänster dynamiskt kan skala ut vid högre last eller skala ner vid lägre last. Detta har möjliggjorts genom att arkitekta om en existerande VPKI till en cloud-native lösning driftsatt som mikrotjänster. En av nyckelutmaningarna till att ha en pålitlig arkitektur baserad på distribuerade mikrotjänster är sybil-baserad missuppförande. Genom att utnyttja Sybil baserade attacker på VPKI, kan illvilliga fordon påverka trafik att tjäna dess egna syften. Därför är det av största vikt att förhindra Sybil attacker. Å andra sidan så dras traditionella metoder att stoppa dem med prestandakostnader. Vi föreslår en lösning för att adressera Sybilbaserade attacker genom att nyttja Redis, en in-memory data-store utan att märkbart kompromissa på systemets effektivitet och prestanda. Att köra våra VPKI tjänster på Google Cloud Platform (GCP) och genomföra diverse stresstester mot dessa har visat att storskaliga driftsättningar av VPKI as a Service (VPKIaaS) kan göras effektivt samtidigt som riktigt trafik hanteras. Vi har testat VPKIaaS under syntetisk genererat normalt trafikflöde samt flow och flash mängd scenarier. Det har visat sig att VPKIaaS klarar att utfärda 100 pseudonym per förfråga utsänt av 1000 fordon (där fordonen bad om en ny uppsättning pseudonym varje 1 till 5 sekunder), och varje fordon fått svar inom 77 millisekunder. Vi demonstrerar även att under en flashcrowd situation, där antalet fordon höjs till 50000 med en kläckningsgrad på 100. VPKIaaS dynamiskt skalar ut och tar ≈192 millisekunder att betjäna 100 pseudonymer per förfrågan gjord av fordon.

The Domain Name System is a hierarchical naming system that provides information of network resources or services given domain names. DNS applications in vehicular networks raise new challenges with regards to security and privacy of vehicles. In particular, vehicular communications outside the coverage of roadside infrastructure needs to be preserved. Multicast DNS is proposed as a method to restrict queries to vehicles in a Vehicle-to-Everything environment which could include other connected devices. Contemporary DNS applications rely on robust security protocols provided by the DNS Security Extensions to authenticate responses and verify resource records. Vehicular DNS communications need authentication to verify the source and legitimacy of DNS resource records. This can be achieved through multihop Vehicle- to-Vehicle communications to reach a name server supplemented by a novel approach to verify records using the Bloom filter.In this thesis, we analyze the security and privacy risks posed by a non-authenticated baseline communication protocol. We then build a secure and privacy-preserving networked system based on pseudonym certificate-based public key infrastructure solution. The experimental analysis confirmed the improvement on security and privacy at the cost of communication and computation overhead. / Domännamnssystemet är en hierarkisk benämningssystem som ger information om nätverksresurser eller tjänster för givna domännamn. DNS application i fordon nätverk framkallar nya utmaningar när det handlar om datasäkerhet och fordons integritet. Det är särskilt fordon kommunikation utanför vägkant-infrastrukturens räckvidd som behöver bevara och försäkra operationer av DNS applikation i fordon nätverk. Multicast DNS är en föreslagen metod för att begränsa förfrågan till fordon i en fordon-till-all-miljö som kan inkludera andra anslutna enheter. Nuvarande applikationer förlitar sig på en robust säkerhetsprotokoll som kommer från DNS säkerhetsförlängning för att autentisera svar och verifiera resurs rekord. Fordon DNS kommunikationer behöver autentisering för att verifiera källor och legitimitet av DNS resurs rekord. Detta kan uppnås genom multihop fordon-till-fordon kommunikation för att ansluta sig till en namn server med hjälp av en ny metod för att verifiera uppgifter med hjälp av bloomfilter datastruktur.I tesen analyserar vi risken som finns i en icke-autentiserad integritets-läckande kommunikationsprotokoll. Vi bygger sedan ett nätverk och använder en pseudonym certifikatbaserad publik nyckel infrastruktur lösning för att undersöka förbättringar inom säkerhet och integritet. Analysen från experimenten visar att det finns en förbättring för säkerhet och integritet i utbyte mot tidsprestanda, vilket är en intressant kompromiss.

This research devises a unified method for the distribution of pseudonyms in hybrid ephemeral vehicular networks (VNs), which are often referred to as vehicular ad hoc networks (VANETs), for the purposes of refill, intra-regional, and inter-regional movement. This work addresses a significant impediment to the use of pseudonyms, which has been almost universally accepted (and is on the verge of being standardized by the Institute for Electrical and Electronic Engineers (IEEE) and the Society for Automotive Engineers (SAE) as the best means to balance attribution and privacy to maximize the value of infrastructure deployment and citizen acceptability (i.e. use). The results include a pseudonym distribution protocol that maximizes ease of use while not compromising the security or privacy pseudonyms afford. These results contribute to the solution, in a scalable, adaptive, and bandwidth efficient manner, one of the remaining impediments to the adoption of VANETs. The new method shows improved performance compared to a baseline pseudonym distribution method that does not take these factors into consideration.