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Communication Dans Un Congrès Année : 2014

GGHLite: More Efficient Multilinear Maps from Ideal Lattices

Résumé

The GGH Graded Encoding Scheme, based on ideal lattices, is the first plausible approximation to a cryptographic multilinear map. Unfortunately, using the security analysis in the original paper, the scheme requires very large parameters to provide security for its underlying \enquote{encoding re-randomization} process. Our main contributions are to formalize, simplify and improve the efficiency and the security analysis of the re-randomization process in the GGH construction. This results in a new construction that we call GGHLite. In particular, we first lower the size of a standard deviation parameter of the re-randomization process of the original paper from exponential to polynomial in the security parameter. This first improvement is obtained via a finer security analysis of the drowning step of re-randomization, in which we apply the Rényi divergence instead of the conventional statistical distance as a measure of distance between distributions. Our second improvement is to reduce the number of randomizers needed from $\Omega(n \log n)$ to $2$, where $n$ is the dimension of the underlying ideal lattices. These two contributions allow us to decrease the bit size of the public parameters from $O(\lambda^5 \log \lambda)$ for the GGH scheme to $O(\lambda \log^2 \lambda)$ in GGHLite, with respect to the security parameter $\lambda$ (for a constant multilinearity parameter $\kappa$).
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Dates et versions

hal-00983179 , version 1 (24-04-2014)

Identifiants

  • HAL Id : hal-00983179 , version 1

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Adeline Langlois, Damien Stehlé, Ron Steinfeld. GGHLite: More Efficient Multilinear Maps from Ideal Lattices. EUROCRYPT 2014, May 2014, Copenhague, Denmark. ⟨hal-00983179⟩
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