Description
In this thesis, we study two differentprimitives. Lossy trapdoor functions and zero-knwoledge proof systems.The lossy trapdoor functions (LTFs) arefunction families in which injective functionsand lossy ones are computationally indistin-guishable. Since their introduction, they havebeen found useful in constructing various cryp-tographic primitives. We give in this thesisefficient constructions of two different vari-ants of LTF: Lossy Algebraic Filter andR-LTF. With these two different variants, wecan improve the efficiency of the KDM-CCA(Key-Depended-Message Chosen-Ciphertext-Attack) encryption schemes, fuzzy extractoresand deterministic encryption.In the second part of this thesis, we in-vestigated on constructions of zero-knowledgeproof systems. We give the first logarithmic-size ring-signature with tight security usinga variant of Groth-KolhweizΣ-protocol in therandom oracle model. We also proposed onenew construction of lattice-based Designated-Verifier Non-Interactive Zero-Knowledge argu-ments (DVNIZK). Using this new construction, we build a lattice-based voting scheme in the standard model. lien: rien
Next sessions
-
Lightweight (AND, XOR) Implementations of Large-Degree S-boxes
Speaker : Marie Bolzer - LORIA
The problem of finding a minimal circuit to implement a given function is one of the oldest in electronics. In cryptography, the focus is on small functions, especially on S-boxes which are classically the only non-linear functions in iterated block ciphers. In this work, we propose new ad-hoc automatic tools to look for lightweight implementations of non-linear functions on up to 5 variables for[…]-
Cryptography
-
Symmetrical primitive
-
Implementation of cryptographic algorithm
-
-
Algorithms for post-quantum commutative group actions
Speaker : Marc Houben - Inria Bordeaux
At the historical foundation of isogeny-based cryptography lies a scheme known as CRS; a key exchange protocol based on class group actions on elliptic curves. Along with more efficient variants, such as CSIDH, this framework has emerged as a powerful building block for the construction of advanced post-quantum cryptographic primitives. Unfortunately, all protocols in this line of work are[…] -
Endomorphisms via Splittings
Speaker : Min-Yi Shen - No Affiliation
One of the fundamental hardness assumptions underlying isogeny-based cryptography is the problem of finding a non-trivial endomorphism of a given supersingular elliptic curve. In this talk, we show that the problem is related to the problem of finding a splitting of a principally polarised superspecial abelian surface. In particular, we provide formal security reductions and a proof-of-concept[…]-
Cryptography
-