This paper addresses the question of how often the square code of an arbitrary l-dimensional subcode of the code GRSk(a, b) is exactly the code GRS2k-1(a,b* b). To answer this question we first introduce the notion of gaps of a code which allows us to characterize such subcodes easily. This property was first stated and used in  where Wieschebrink applied the Sidelnikov-Shestakov attack  to brake the Berger-Loidreau cryptostystem .
|Title of host publication||Seventh International Workshop on Coding and Cryptography 2011 (WCC 2011, Paris, France, April 11-15, 2011)|
|Publication status||Published - 2011|