International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 21 May 2015

Shi Bai, Adeline Langlois, Tancr{\\`e}de Lepoint, Damien Stehl\
ePrint Report ePrint Report
The R\\\'enyi divergence is a measure of closeness of two

probability distributions. We show that it can often be used as an alternative

to the statistical distance in security proofs for lattice-based

cryptography. Using the R\\\'enyi divergence is particularly suited

for security proofs of primitives in which the attacker is required

to solve a search problem (e.g., forging a signature). We show that

it may also be used in the case of distinguishing problems (e.g.,

semantic security of encryption schemes), when they enjoy a public

sampleability property. The techniques lead to security proofs for

schemes with smaller parameters, and sometimes to simpler security

proofs than the existing ones.

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