Patent ID: 8634554

Claim:
A method to enforce, by a management center, access rules to a broadcast product received by receivers, the method comprising: preparing, by a management center processor, an authorization message for giving access to a product accessible by a least a first subscription package and not accessible by at least a second subscription package, the access to said product being released by a product key, said management center managing a plurality of subscription packages for which at least one subscription package allows the access to the product, each of the subscription packages having at least a positive key material and a negative key material, the positive key material comprising at least a positive key and being intended for receivers that have subscribed to the subscription package, the negative key material comprising at least a negative key and being intended for receivers that have not subscribed to the subscription package, each receiver that has access to a subscription package having stored therein a positive key material of said subscription package and the negative key material of the subscription packages for which no subscription was made, the product key or a data allowing retrieval of the product key being used to produce a cryptogram, said cryptogram being encrypted by the positive key of the first subscription package and the negative key of the second subscription package so that the cryptogram allowing retrieval of the product key is accessible only when both the positive key material of the first subscription package and negative key material of the second subscription package are present in the receiver.