We give polynomial time attacks on the McEliece public key cryptosystem based either on algebraic geometry (AG) codes or on small codimensional subcodes of AG codes. These attacks consist in the blind reconstruction either of an Error Correcting Pair (ECP), or an Error Correcting Array (ECA) from the single data of an arbitrary generator matrix of a code. Take notice that the choice of computing an ECP or an ECA depends on the number of errors that we need to correct: an ECP provides a decoding algorithm that corrects up to d * −1−g 2 errors, where d * denotes the designed distance and g denotes the genus of the corresponding curve; while with an ECA the decoding algorithm arrives up to d * −1 2 errors. Roughly speaking, for a public code of length n over F q , these attacks run in O(n 4 log(n)) operations in F q for the reconstruction of an ECP and O(n 5) operations for the reconstruction of an ECA. A probabilistic shortcut allows to reduce the complexities respectively to O(n 3+ε log(n)) and O(n 4+ε). Compared to the previous known attack due to Faure and Minder, our attack is efficient on codes from curves of arbitrary genus. Furthermore we investigate how far these methods apply to subcodes of AG codes.