In the present article, we discuss the decoding of Gabidulin and related
codes from a cryptographic perspective and we observe that these codes can be
decoded with the single knowledge of a generator matrix. Then, we extend and
revisit Gibson's and Overbeck's attacks on the generalised GPT encryption
scheme (instantiated with Gabidulin codes) for various ranks of the distortion
matrix and apply our attack to the case of an instantiation with twisted
Gabidulin codes