Public key infrastructure (Computer security)

With the issuance of the Notice of Proposed Rule Making (NPRM) for Vehicle
to Vehicle (V2V) communications by the United States National Highway Tra c
Safety Administration (NHTSA), the goal of the widespread deployment of vehicular
networking has taken a signi cant step towards becoming a reality. In order for
consumers to accept the technology, it is expected that reasonable mechanisms will
be in place to protect their privacy. Cooperative Caching has been proposed as an
approach that can be used to improve privacy by distributing data items throughout
the mobile network as they are requested. With this approach, vehicles rst attempt
to retrieve data items from the mobile network, alleviating the need to send all requests
to a centralized location that may be vulnerable to an attack. However, with
this approach, a requesting vehicle may expose itself to many unknown vehicles as
part of the cache discovery process.
In this work we present a Public Key Infrastructure (PKI) based Cooperative
Caching system that utilizes a genetic algorithm to selectively choose members of the
mobile network to query for data items with a focus on improving overall privacy. The
privacy improvement is achieved by avoiding those members that present a greater risk of exposing information related to the request and choosing members that have a
greater potential of having the needed data item. An Agent Based Model is utilized
to baseline the privacy concerns when using a broadcast based approach to cache
discovery. In addition, an epidemiology inspired mathematical model is presented to
illustrate the impact of reducing the number of vehicles queried during cache discovery.
Periodic reports from neighboring vehicles are used by the genetic algorithm to
identify which neighbors should be queried during cache discovery. In order for the
system to be realistic, vehicles must trust the information in these reports. A PKI
based approach used to evaluate the trustworthiness of each vehicle in the system is
also detailed. We have conducted an in-depth performance study of our system that
demonstrates a signi cant reduction in the overall risk of exposure when compared
to broadcasting the request to all neighbors.

Consider a scenario where a server S shares a symmetric key kU with each user U. Building on a 2-party solution of Bohli et al., we describe an authenticated 3-party key establishment which remains secure if a computational Bilinear Diffie Hellman problem is hard or the server is uncorrupted. If the BDH assumption holds during a protocol execution, but is invalidated later, entity authentication and integrity of the protocol are still guaranteed. Key establishment protocols based on hardness assumptions, such as discrete logarithm problem (DLP) and integer factorization problem (IFP) are vulnerable to quantum computer attacks, whereas the protocols based on other hardness assumptions, such as conjugacy search problem and decomposition search problem can resist such attacks. The existing protocols based on the hardness assumptions which can resist quantum computer attacks are only passively secure. Compilers are used to convert a passively secure protocol to an actively secure protoc ol. Compilers involve some tools such as, signature scheme and a collision-resistant hash function. If there are only passively secure protocols but not a signature scheme based on same assumption then the application of existing compilers requires the use of such tools based on different assumptions. But the introduction of new tools, based on different assumptions, makes the new actively secure protocol rely on more than one hardness assumptions. We offer an approach to derive an actively secure two-party protocol from a passively secure two-party protocol without introducing further hardness assumptions. This serves as a useful formal tool to transform any basic algebric method of public key cryptography to the real world applicaticable cryptographic scheme. In a recent preprint, Vivek et al. propose a compiler to transform a passively secure 3-party key establishment to a passively secure group key establishment. To achieve active security, they apply this compiler to Joux's

We present an Identity-Based Encryption scheme, 1-Key-Encrypt-Then-MAC, in which we are able to verify the authenticity of messages using a MAC. We accomplish this authentication by combining an Identity-Based Encryption scheme given by Boneh and Franklin, with an Identity-Based Non-Interactive Key Distribution given by Paterson and Srinivasan, and attaching a MAC. We prove the scheme is chosen plaintext secure and chosen ciphertext secure, and the MAC is existentially unforgeable.