A method to enforce by a management center access rules for a broadcast product accessed by an access key, the management center managing a plurality of Boolean positive and negative attributes, comprising the steps: associating one positive Boolean attribute to a receiver entitled to the attribute and loading the same; associating one negative Boolean attribute to a receiver not entitled to the attribute and loading the same; defining at least a second broadcast encryption scheme for the negative Boolean attributes and associating each negative Boolean attribute corresponding decryption key material; expressing access conditions on a product as a Boolean expression by combining at least one positive Boolean attribute and at least one negative Boolean attribute by at least one Boolean conjunction or disjunction; generating and broadcasting at least one cryptogram to a receiver, encrypting the access key with the two combined broadcast encryption schemes according to the Boolean expression.