[Focus on] Cybersecurity Research activities of the CAS3C3 Team of
Laboratoire Jean Kuntzmann
Cybersecurity research activities of the CAS3C3
team (computer algebra, security, complex systems, codes, secrets,
cryptology) are focused on
- Design and analysis of symmetric cryptographic primitives and
their secure and efficient implementation.
- Proof of work certificates for outsourced cloud computing.
- Fault tolerant schemes in linear algebra.
- Secure protocols for multi-party, zero-knowledge, blockchains or
industrial control systems.
Proof of work certificates for outsourced cloud computing,
where a client can not blindly trust the answer of remote
Efficiently and reliably delegating computations.
The idea is to design algorithms that can form a proof of
correctness of a result computed via a probabilistic algorithm or
through a potentially unreliable computing center.
The difficulty is to design proofs that are verifiable at a lower cost
(time, memory, ...) than that of recomputing the result. Blockchain
technologies fo rinstance, use these techniques.
Explicit computation of (freestart) collisions for the SHA-1
Signed non-linear differential path used in the computation of the
second block of a collision for the SHA-1 hash function.
Hash functions, of which SHA-1 is an example, are ubiquitous primitives in cryptography. It was known since 2005 that SHA-1 was vulnerable to collision attacks, yet it remained used in many industrial products. From 2014 to 2017, a series of work involving CASC team member Pierre Karpman improved the existing attacks and ultimately lead to an explicit computation of a collision for SHA-1. This had a positive impact on the withdrawal of this function from vulnerable systems.
Fault tolerant schemes for linear algebra
Solving linear systems of parametric equations:
Error correction in fast exact linear algebra:
Error correction in fast matrix multiplication and inverse
Factorization with errors:
Information retrievability, proofs and security
XPIR : Private Information Retrieval for Everyone
Proofs of Retrievability with Low Server Storage
high-order masking schemes for finite-field multiplication
A 3-NI multiplication gadget over F2 and any extension thereof.
Physical side-channel attacks are a significant threat for embedded
implementations of cryptosystems. An efficient countermeasure
against some of these attacks is the use of masked
operations, whereby one splits sensitive data into several
shares and uses multiparty computation secure in a
probing model to compute a shared result.
Team members' activities include the study of efficient algorithms to
evaluate the security of given masking schemes, and the design of
new gadgets for various operations.
In Conspiracy Santa, a variant of Secret Santa, a group of people
offer each other Christmas gifts, where each member of the group
receives a gift from the other members of the group. We have
invented a protocol that allows a group of people to share the
expenses for the gifts in such a way that no participant will
learn the price of his gift. Our solution does not require a
trusted third party, and can either be implemented physically (the
participants are in the same room and exchange money) or,
virtually, using a cryptocurrency.
More generally, we research on Physical Cryptography, the
art of designing protocols that can be ran without computers, for
instance using only pencil and paper or cards.
Private Multi-party linear algebra and trust
Secure multiparty computations (MPC) allows n players to compute
together the output of some function, using private inputs without
revealing them. This is useful, e.g., for a distributed evaluation
of trust where players compute a confidence level by combining
their mutual degrees of trust, but without revealing their
Security architectures for industrial control systems
LocalPKI: A user-centric,
interoperable and IoT friendly, formally proven PKI. This security
infrastructure can use blockchain technologies and be
used in constrained environments, for instance for IoT, but also
for Supervisory Control and Data Acquisition (SCADA) architectures.
Secured Industrial control systems:
Last modified: Wed Jun 9 11:51:58 CEST 2021