normal_cdt.h File Reference

Normal sampler that samples from small fixed half-Gaussian distribution. More...

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Functions
void	cfe_normal_cdt_sample (mpz_t res)

Detailed Description

Normal sampler that samples from small fixed half-Gaussian distribution.

Function Documentation

cfe_normal_cdt_sample()

void cfe_normal_cdt_sample

(

mpz_t

res

)

cfe_normal_cdt_sample samples random values from the discrete Normal (Gaussian) probability distribution, limited to non-negative values (half-Gaussian). In particular each value x from Z^+ is sampled with probability proportional to exp(-x^2/sigma^2) where sigma = sqrt(1/(2ln(2))). The implementation is based on paper: "FACCT: FAst, Compact, and Constant-Time Discrete Gaussian Sampler over Integers" by R. K. Zhao, R. Steinfeld, and A. Sakzad (https://eprint.iacr.org/2018/1234.pdf). See the above paper where it is argued that such a sampling achieves a relative error at most 2^{-46} with the chosen parameters.

Parameters

res	The result of sampling will be saved here