Secure multicast transmission

A method of multicasting data. The method includes providing a data block for multicasting, generating a plurality of segments that represent the data block, such that a receiver needs to receive fewer than all the generated segments in order to reconstruct the data block, encrypting at least a portion of the generated segments, so as to generate encrypted data units encrypted with a plurality of different keys or encryption methods and transmitting the encrypted data units over one or more multicast channels.