  In this article, we discuss the decoding of Gabidulin and related codes from
a cryptographic point of view, and we observe that these codes can be decoded
solely from the knowledge of a generator matrix. We then extend and revisit
Gibson and Overbeck attacks on the generalized GPT encryption scheme
(instantiated with the Gabidulin code) for different ranks of the distortion
matrix. We apply our attack to the case of an instantiation with twisted
Gabidulin codes.
