Description
In this talk a structural attack on the McEliece/Niederreiter public key cryptosystem based on subcodes of generalized Reed-Solomon (GRS) codes is presented. It allows the reconstruction of the private key for almost all practical parameter choices in polynomial time with high probability. The main step of the attack consists in constructing a related full GRS code from the subcode by componentwise multiplication of codewords. This allows the application of the Sidelnikov-Shestakov algorithm to recover the parameters of the GRS code.