Severely denting the Gabidulin version of the McEliece Public Key Cryptosystem

Gabidulin has proposed a version of the McEliece Public Key Cryptosystem using what he calls maximum rank distance (MRD) codes in place of Goppa codes. It is shown how to break such a system by finding a trapdoor to it. For the size of code he suggests this can be done in about a week on a fast personal computer. The attack can be thwarted by increasing the size of the code, but the advantages claimed for the Gabidulin version over the McEliece version are then largely lost.