Philippe Gaborit - RankSign: An Efficient Signature Algorithm Based on the Rank Metric

Philippe Gaborit of the University of Limoges and the XLIM Research Institute presented a talk titled: RankSign: An efficient signature algorithm based on the rank metric at the 2014 PQCrypto conference in October, 2014. Abstract: In this paper we propose a new approach to code-based signatures that makes use in particular of rank metric codes. When the classical approach consists in finding the unique preimage of a syndrome through a decoding algorithm, we propose to introduce the notion of mixed decoding of erasures and errors for building signature schemes. In that case the difficult problem becomes, as in the case in lattice-based cryptography, finding a preimage of weight above the Gilbert-Varshamov bound (case where many solutions occur) rather than finding a unique preimage of weight below the Gilbert-Varshamov bound. The paper describes RankSign: a new signature algorithm for the rank metric based on a new mixed algorithm for decoding erasures and errors for the recently introduced Low Rank Parity Check (LRPC) codes. We explain how it is possible (depending on choices of parameters) to obtain a full decoding algorithm which is able to find a preimage of reasonable rank weight for any random syndrome with a very strong probability. We study the semantic security of our signature algorithm and show how it is possible that no information leaks through signatures. Finally we give several examples of parameters for our scheme, some of which with public key of size 11, 520 bits and signature of size 1728 bits. Moreover the scheme can be very fast for small base fields. PQCrypto 2014 Book: http://www.springer.com/computer/security+and+cryptology/book/978-3-319-11658-7 Workshop: https://pqcrypto2014.uwaterloo.ca/ Find out more about IQC! Website - https://uwaterloo.ca/institute-for-qu... Facebook - https://www.facebook.com/QuantumIQC Twitter - https://twitter.com/QuantumIQC