Patent ID: 8549287

Claim:
A method, comprising: encrypting a multicast message by using ciphering in a multicast service control device, wherein, for ciphering, a ciphering key is used; sending the encrypted multicast message from the multicast service control device to a plurality of user entities; sending, in a first message when a user entity from the plurality of user entities registers with a multicast service, a first part of a ciphering information to the user entity; and sending, in a second message, a second part of the ciphering information to the user entity, when a multicast transmission of encrypted messages is activated by the multicast service control device; wherein the ciphering information comprises at least one parameter from which the ciphering key is derived, wherein the ciphering key is derived by at least one of the plurality of user entities based on at least the first part of the ciphering information and the second part of the ciphering information forming the at least one parameter.