An analysis of Coggia-Couvreur attack on Loidreau's rank-metric public key encryption scheme in the general case

Abstract: In this paper we show that in the case where the public-key can be distinguished from a random code in Loidreau's encryption scheme, then Coggia-Couvreur attack can be extended to recover an equivalent secret key. This attack can be conducted in polynomial-time if the masking vector space has dimension 3, thus recovering the results of Ghatak.