401 research outputs found
Hard isogeny problems over RSA moduli and groups with infeasible inversion
We initiate the study of computational problems on elliptic curve isogeny
graphs defined over RSA moduli. We conjecture that several variants of the
neighbor-search problem over these graphs are hard, and provide a comprehensive
list of cryptanalytic attempts on these problems. Moreover, based on the
hardness of these problems, we provide a construction of groups with infeasible
inversion, where the underlying groups are the ideal class groups of imaginary
quadratic orders.
Recall that in a group with infeasible inversion, computing the inverse of a
group element is required to be hard, while performing the group operation is
easy. Motivated by the potential cryptographic application of building a
directed transitive signature scheme, the search for a group with infeasible
inversion was initiated in the theses of Hohenberger and Molnar (2003). Later
it was also shown to provide a broadcast encryption scheme by Irrer et al.
(2004). However, to date the only case of a group with infeasible inversion is
implied by the much stronger primitive of self-bilinear map constructed by
Yamakawa et al. (2014) based on the hardness of factoring and
indistinguishability obfuscation (iO). Our construction gives a candidate
without using iO.Comment: Significant revision of the article previously titled "A Candidate
Group with Infeasible Inversion" (arXiv:1810.00022v1). Cleared up the
constructions by giving toy examples, added "The Parallelogram Attack" (Sec
5.3.2). 54 pages, 8 figure
New Digital Signature Algorithm EHTv2
Every public-key encryption/decryption algorithm where the
set of possible plain-texts is identical to the set of possible cipher-texts
may be converted into a digital signature algorithm. That is quite different
in the lattice (code)-based public-key cryptography. The decryption algorithm on a random input produces a valid plain-text, that is a signature, with a negligible probability. That explains why it is so difficult to construct a new secure and efficient lattice-based digital signature system. Though several solutions are known and taking part in the NIST Post Quantum Standardisation Process there is still a need to construct digital signature algorithms based on new principles. In this work, a new and efficient digital signature algorithm is suggested. Its design is simple and transparent. Its security is based on the hardness of an approximate closest vector problem in the maximum norm for some q-ary lattices. The signature is several times shorter than that provided by the NIST Selected Digital Signature Algorithms with comparable security level, while the public key size is larger
Some Applications of Coding Theory in Cryptography
viii+80hlm.;24c
Security architecture for law enforcement agencies
In order to carry out their duty to serve and protect, law enforcement agencies
(LEAs) must deploy new tools and applications to keep up with the pace of evolving
technologies. However, police information and communication technology (ICT) systems
have stringent security requirements that may delay the deployment of these new applications,
since necessary security measures must be implemented first. This paper presents an integrated
security architecture for LEAs that is able to provide common security services to novel and
legacy ICT applications, while fulfilling the high security requirements of police forces. By
reusing the security services provided by this architecture, new systems do not have to
implement custom security mechanisms themselves, and can be easily integrated into existing
police ICT infrastructures. The proposed LEA security architecture features state-of-the-art
technologies, such as encrypted communications at network and application levels, or multifactor
authentication based on certificates stored in smart cards.Web of Science7517107321070
The Impact of Quantum Computing on Present Cryptography
The aim of this paper is to elucidate the implications of quantum computing
in present cryptography and to introduce the reader to basic post-quantum
algorithms. In particular the reader can delve into the following subjects:
present cryptographic schemes (symmetric and asymmetric), differences between
quantum and classical computing, challenges in quantum computing, quantum
algorithms (Shor's and Grover's), public key encryption schemes affected,
symmetric schemes affected, the impact on hash functions, and post quantum
cryptography. Specifically, the section of Post-Quantum Cryptography deals with
different quantum key distribution methods and mathematicalbased solutions,
such as the BB84 protocol, lattice-based cryptography, multivariate-based
cryptography, hash-based signatures and code-based cryptography.Comment: 10 pages, 1 figure, 3 tables, journal article - IJACS
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