Junior professorship with tenure track in computer algebra, University of Ulm, Germany
A successful candidate should be an excellent young researcher with a focus in computeralgebra specializing for example in number theory, algebraic geometry, cryptography, combinatorics, or symbolic computation. Collaboration within the university and as well as the acquisition of third party funding is desired.
Balanced Encoding to Mitigate Power Analysis: A Case Study, by Cong Chen and Thomas Eisenbarth and Aria Shahverdi and Xin Ye
Most side channel countermeasures for software implementations of cryptography either rely on masking or randomize the execution
order of the cryptographic implementation. This work proposes a countermeasure that has constant leakage in common linear leakage models.
Constant leakage is achieved not only for internal state values, but also for
their transitions. The proposed countermeasure provides perfect protection in the theoretical leakage model. To study the practical relevance of
the proposed countermeasure, it is applied to a software implementation
of the block cipher Prince. This case study allows us to give realistic values
for resulting implementation overheads as well as for the resulting side
channel protection levels that can be achieved in realistic implementation
Post-Doc, University of Luxembourg
The position arises from a recently awarded joint project with the University of Nancy and ENS Cachin Paris. The postdoc position involves the study of process equivalences to model the security of protocols employing weak secrets, such as voting and password based protocols.
Further details on these positions and their requirements are available at the following urls:
The research will be conducted at the Interdisciplinary Centre for Security, Reliability and Trust (SnT) in the research group ApSIA (Applied Security and Information Assurance) headed by Prof. Dr. Peter Y.A Ryan. Contact Prof Ryan, peter.ryan (at) uni.lu, for more information.
The University offers highly competitive salaries and is an equal opportunity employer.
Tree-Structured Composition of Homomorphic Encryption: How to Weaken Underlying Assumptions, by Koji Nuida and Goichiro Hanaoka and Takahiro Matsuda
Cryptographic primitives based on infinite families of progressively weaker assumptions have been proposed by Hofheinz-Kiltz and by Shacham (the n-Linear assumptions) and by Escala et al. (the Matrix Diffie-Hellman assumptions). All of these assumptions are extensions of the decisional Diffie-Hellman (DDH) assumption. In contrast, in this paper, we construct (additive) homomorphic encryption (HE) schemes based on a new infinite family of assumptions extending the decisional Composite Residuosity (DCR) assumption. This is the first result on a primitive based on an infinite family of progressively weaker assumptions not originating from the DDH assumption. Our assumptions are indexed by rooted trees, and provides a completely different structure compared to the previous extensions of the DDH assumption.
Our construction of a HE scheme is generic; based on a tree structure, we recursively combine copies of building-block HE schemes associated to each leaf of the tree (e.g., the Paillier cryptosystem, for our DCR-based result mentioned above). Our construction for depth-one trees utilizes the \"share-then-encrypt\" multiple encryption paradigm, modified appropriately to ensure security of the resulting HE schemes. We prove several separations between the CPA security of our HE schemes based on different trees; for example, the existence of an adversary capable of breaking all schemes based on depth-one trees, does not imply an adversary against our scheme based on a depth-two tree (within a computational model analogous to the generic group model). Moreover, based on our results, we give an example which reveals a type of \"non-monotonicity\" for security of generic constructions of cryptographic schemes and their building-block primitives; if the building-block primitives for a scheme are replaced with other ones secure under stronger assumptions, it may happen that the resulting scheme becomes secure under a weaker assumption than the original.
PhD students and Postdoctoral Fellowships in Post-Quantum Cryptography, University of Waterloo
The Institute for Quantum Computing and the Centre for Applied Cryptographic Research at the University of Waterloo seek qualified applicants for postdoctoral fellowships and graduate student positions in post-quantum cryptography, in particular in public-key cryptography based on computational assumptions believed to be secure against quantum computers (e.g. systems based on lattices, error-correcting codes codes, multivariate functions, elliptic curve isogenies, and also signature schemes based on hash-functions).
Projects may include studying new attacks (classical or quantum) on proposed systems, improved implementation methods for such systems, and reductions or equivalences between candidate post-quantum systems.
Successful applications will join a broad team of leading researchers in quantum computing and applied cryptography. They will also be able to take advantage of the CryptoWorks21 supplementary training program, which develops the technical and professional skills and knowledge needed to create cryptographic solutions that will be safe in a world with quantum computing technologies.
On a new fast public key cryptosystem, by Samir Bouftass.
This paper presents a new fast public key cryptosystem namely : A key exchange algorithm, a public key encryption algorithm and a digital signature algorithm, based on a the difficulty to invert the following function :
$F(X) =(A\\times X)Mod(2^r)Div(2^s)$ .\\\\* Mod is modulo operation , Div is integer division operation , A , r and s are known natural numbers while $( r > s )$ .\\\\* In this paper it is also proven that this problem is equivalent to SAT problem which is NP complete .