The invention relates to a method for broadcasting data in a system using a BES (A1) stateless scheme using a binary tree T with a KEKs No 2 key structure, i.e. such that a key ki,j is associated with each difference of subsets Si,j, and a root key k0, - - - associated with the set of the tree T and a BES (A2) “stateful” scheme using the same binary tree T with a KEKs No 1 key structure, i.e. such that a key ki is associated with each subtree Si wherein the scheme (A1) is used for the current broadcast session and the keys known by the denied users are updated with a “stateful” scheme (A2) from time to time.