Description
NIST’s post-quantum cryptography competition has entered in its second phase, the time has come to focus more closely on practical aspects of the candidates. On the lattice-based side, certain schemes chose to implement discrete Gaussian distributions which allow better parameters and security reductions. However, this advantage has also proved to be their Achilles’ heel, as discrete Gaussians pose serious challenges in terms of protection against timing attacks. In this talk, I will review the different timing weaknesses and present several constant-time techniques including a new approach to polynomially approximate transcendental functions (https://eprint.iacr.org/2019/511.pdf). I will emphasis on the application of these techniques on BLISS and FALCON signature schemes (https://tprest.github.io/pdf/pub/simple-fast-gaussian.pdf). We will see that the efficiency loss in the resulting implementations is reasonably low compared to the non constant-time.<br/> lien: http://desktop.visio.renater.fr/scopia?ID=729028***8178&autojoin
Next sessions
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Efficient zero-knowledge proofs and arguments in the CL framework
Speaker : Agathe Beaugrand - Institut de Mathématiques de Bordeaux
The CL encryption scheme, proposed in 2015 by Castagnos and Laguillaumie, is a linearly homomorphic encryption scheme, based on class groups of imaginary quadratic fields. The specificity of these groups is that their order is hard to compute, which means it can be considered unknown. This particularity, while being key in the security of the scheme, brings technical challenges in working with CL,[…] -
Constant-time lattice reduction for SQIsign
Speaker : Sina Schaeffler - IBM Research
SQIsign is an isogeny-based signature scheme which has recently advanced to round 2 of NIST's call for additional post-quantum signatures. A central operation in SQIsign is lattice reduction of special full-rank lattices in dimension 4. As these input lattices are secret, this computation must be protected against side-channel attacks. However, known lattice reduction algorithms like the famous[…] -
Circuit optimisation problems in the context of homomorphic encryption
Speaker : Sergiu Carpov - Arcium
Fully homomorphic encryption (FHE) is an encryption scheme that enables the direct execution of arbitrary computations on encrypted data. The first generation of FHE schemes began with Gentry's groundbreaking work in 2019. It relies on a technique called bootstrapping, which reduces noise in FHE ciphertexts. This construction theoretically enables the execution of any arithmetic circuit, but[…] -
TBD
Speaker : Maria Corte-Real Santos - ENS Lyon
TBD-
Cryptography
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