Two modifications for Loidreau’s code-based cryptosystem

This paper presents two modifications for Loidreau’s cryptosystem, a rank metric-based cryptosystem constructed by using Gabidulin codes in the McEliece setting. Recently polynomial-time key recovery attack was proposed to break this some cases. To prevent attack, we propose use of subcodes disguise secret Modification I. In II, choose random matrix low column mix with matrix. Our analysis shows that these can both resist existing structural attacks. Furthermore, have much more compact representation public keys compared Classic McEliece, which has been selected into fourth round NIST-PQC project.