### Lattice Signatures and Bimodal Gaussians

Léo Ducas, Alain Durmus, Tancrède Lepoint, and Vadim Lyubashevsky

##### Abstract

Our main result is a construction of a lattice-based digital signature scheme that represents an improvement, both in theory and in practice, over today's most efficient lattice schemes. The novel scheme is obtained as a result of a modification of the rejection sampling algorithm that is at the heart of Lyubashevsky's signature scheme (Eurocrypt, 2012) and several other lattice primitives. Our new rejection sampling algorithm which samples from a bimodal Gaussian distribution, combined with a modified scheme instantiation, ends up reducing the standard deviation of the resulting signatures by a factor that is asymptotically square root in the security parameter. The implementations of our signature scheme for security levels of 128, 160, and 192 bits compare very favorably to existing schemes such as RSA and ECDSA in terms of efficiency. In addition, the new scheme has shorter signature and public key sizes than all previously proposed lattice signature schemes. As part of our implementation, we also designed several novel algorithms which could be of independent interest. Of particular note, is a new algorithm for efficiently generating discrete Gaussian samples over Z^n. Current algorithms either require many high-precision floating point exponentiations or the storage of very large pre-computed tables, which makes them completely inappropriate for usage in constrained devices. Our sampling algorithm reduces the hard-coded table sizes from linear to logarithmic as compared to the time-optimal implementations, at the cost of being only a small factor slower.

Available format(s)
Category
Public-key cryptography
Publication info
A major revision of an IACR publication in CRYPTO 2013
Keywords
digital signaturespublic-key cryptographylattice techniques
Contact author(s)
tancrede lepoint @ cryptoexperts com
History
2013-12-10: last of 2 revisions
See all versions
Short URL
https://ia.cr/2013/383

CC BY

BibTeX

@misc{cryptoeprint:2013/383,
author = {Léo Ducas and Alain Durmus and Tancrède Lepoint and Vadim Lyubashevsky},
title = {Lattice Signatures and Bimodal Gaussians},
howpublished = {Cryptology ePrint Archive, Paper 2013/383},
year = {2013},
note = {\url{https://eprint.iacr.org/2013/383}},
url = {https://eprint.iacr.org/2013/383}
}

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