43,120 research outputs found
Cryptanalysis of an Efficient Signcryption Scheme with Forward Secrecy Based on Elliptic Curve
The signcryption is a relatively new cryptographic technique that is supposed
to fulfill the functionalities of encryption and digital signature in a single
logical step. Several signcryption schemes are proposed throughout the years,
each of them having its own problems and limitations. In this paper, the
security of a recent signcryption scheme, i.e. Hwang et al.'s scheme is
analyzed, and it is proved that it involves several security flaws and
shortcomings. Several devastating attacks are also introduced to the mentioned
scheme whereby it fails all the desired and essential security attributes of a
signcryption scheme.Comment: 5 Pages, 2 Figure
BlockPKI: An Automated, Resilient, and Transparent Public-Key Infrastructure
This paper describes BlockPKI, a blockchain-based public-key infrastructure
that enables an automated, resilient, and transparent issuance of digital
certificates. Our goal is to address several shortcomings of the current TLS
infrastructure and its proposed extensions. In particular, we aim at reducing
the power of individual certification authorities and make their actions
publicly visible and accountable, without introducing yet another trusted third
party. To demonstrate the benefits and practicality of our system, we present
evaluation results and describe our prototype implementation.Comment: Workshop on Blockchain and Sharing Economy Application
Keeping Authorities "Honest or Bust" with Decentralized Witness Cosigning
The secret keys of critical network authorities - such as time, name,
certificate, and software update services - represent high-value targets for
hackers, criminals, and spy agencies wishing to use these keys secretly to
compromise other hosts. To protect authorities and their clients proactively
from undetected exploits and misuse, we introduce CoSi, a scalable witness
cosigning protocol ensuring that every authoritative statement is validated and
publicly logged by a diverse group of witnesses before any client will accept
it. A statement S collectively signed by W witnesses assures clients that S has
been seen, and not immediately found erroneous, by those W observers. Even if S
is compromised in a fashion not readily detectable by the witnesses, CoSi still
guarantees S's exposure to public scrutiny, forcing secrecy-minded attackers to
risk that the compromise will soon be detected by one of the W witnesses.
Because clients can verify collective signatures efficiently without
communication, CoSi protects clients' privacy, and offers the first
transparency mechanism effective against persistent man-in-the-middle attackers
who control a victim's Internet access, the authority's secret key, and several
witnesses' secret keys. CoSi builds on existing cryptographic multisignature
methods, scaling them to support thousands of witnesses via signature
aggregation over efficient communication trees. A working prototype
demonstrates CoSi in the context of timestamping and logging authorities,
enabling groups of over 8,000 distributed witnesses to cosign authoritative
statements in under two seconds.Comment: 20 pages, 7 figure
Smart Ticket Protection: An Architecture for Cyber-Protecting Physical Tickets Using Digitally Signed Random Pattern Markers
In order to counter forgeries of tickets for public transport or mass events,
a method to validate them, using printed unique random pattern markers was
developed. These markers themselves are unforgeable by their physically random
distribution. To assure their authenticity, however, they have to be
cryptographically protected and equipped with an environment for successful
validation, combining physical and cyber security protection. This paper
describes an architecture for cryptographically protecting these markers, which
are stored in Aztec codes on physical tickets, in order to assure that only an
authorized printer can generate a valid Aztec code of such a pattern, thus
providing forge protection in combination with the randomness and uniqueness of
the pattern. Nevertheless, the choice of the signature algorithm is heavily
constrained by the sizes of the pattern, ticket provider data, metadata and the
signature confronted by the data volume the code hold. Therefore, this paper
also defines an example for a signature layout for the proposed architecture.
This allows for a lightweight ticket validation system that is both physically
and cryptographically secured to form a smart solution for mass access
verification for both shorter to longer periods at relatively low cost.Comment: 4 pages, 2 figure
PKI Scalability Issues
This report surveys different PKI technologies such as PKIX and SPKI and the
issues of PKI that affect scalability. Much focus is spent on certificate
revocation methodologies and status verification systems such as CRLs,
Delta-CRLs, CRS, Certificate Revocation Trees, Windowed Certificate Revocation,
OCSP, SCVP and DVCS.Comment: 23 pages, 2 figure
Maintaining unlinkability in group based P2P environments
In the wake of the success of Peer-to-Peer (P2P) networking, security has arisen as one of its main concerns, becoming a key issue when evaluating a P2P system. Unfortunately, some systems' design focus targeted issues such as scalabil-ity or overall performance, but not security. As a result, security mechanisms must be provided at a later stage, after the system has already been designed and partially (or even fully) implemented, which may prove a cumbersome proposition. This work exposes how a security layer was provided under such circumstances for a specic Java based P2P framework: JXTA-Overlay.Arran de l'èxit de (P2P) peer-to-peer, la seguretat ha sorgit com una de les seves principals preocupacions, esdevenint una qüestió clau en l'avaluació d'un sistema P2P. Malauradament, alguns sistemes de disseny apunten focus de problemes com l'escalabilitat o l'acompliment general, però no de seguretat. Com a resultat d'això, els mecanismes de seguretat s¿han de proporcionar en una etapa posterior, després que el sistema ja ha estat dissenyat i parcialment (o fins i tot totalment) implementat, la qual cosa pot ser una proposició incòmode. Aquest article exposa com es va proveir una capa de seguretat sota aquestes circumstàncies per un Java específic basat en un marc P2P: JXTA-superposició.A raíz del éxito de (P2P) peer-to-peer, la seguridad ha surgido como una de sus principales preocupaciones, convirtiéndose en una cuestión clave en la evaluación de un sistema P2P. Desgraciadamente, algunos sistemas de diseño apuntan un foco de problemas como la escalabilidad o el desempeño general, pero no de seguridad. Como resultado de ello, los mecanismos de seguridad se proporcionarán en una etapa posterior, después de que el sistema ya ha sido diseñado y parcialmente (o incluso totalmente) implementado, lo que puede ser una proposición incómodo. Este artículo expone cómo se proveyó una capa de seguridad bajo estas circunstancias por un Java específico basado en un marco P2P: JXTA-superposición
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