|Authors||M. Øygarden, D. Smith-Tone and J. Verbel|
|Title||On the Effect of Projection on Rank Attacks in Multivariate Cryptography|
|Project(s)||Simula UiB, Quantum safe cryptography for the Internet of Things|
|Publication Type||Proceedings, refereed|
|Year of Publication||2021|
|Conference Name||The 12th International Conference on Post-Quantum Cryptography (PQCRYPTO 2021)|
|Volume||LNCS, vol 12841|
The multivariate scheme HFEv- used to be considered a promising candidate for a post-quantum signature system. First suggested in the early 2000s, a version of the scheme made it to the third round of the ongoing NIST post-quantum standardization process. In late 2020, the system suffered from an efficient rank attack due to Tao, Petzoldt, and Ding. In this paper, we inspect how this recent rank attack is affected by the projection modification. This modification was introduced to secure the signature scheme PFLASH against its predecessor's attacks. We prove upper bounds for the rank of projected HFEv- (pHFEv-) and PFLASH under the new attack, which are tight for the experiments we have performed. We conclude that projection could be a useful tool in protecting against this recent cryptanalysis.