1. A subscriber television system comprising: a plurality of conditional access systems (CASs) configured to each supply a control word to a first encrypter for use by the first encrypter to encrypt a first stream of packets with each of the control words, wherein the plurality of CASs are provided by physical equipment in a head end of the subscriber television system, the physical equipment including a random control word generator for providing the control word, wherein each of the control words is generated from information contained in an entitlement control message and information from authorization information, the authorization information stored in a set-top box in the subscriber television system, wherein the entitlement control message comprises frequently changing decryption information; the first encrypter configured to: encrypt the first stream of packets to produce a second stream of packets, each packet of the first stream of packets corresponding to a single encrypted packet in the second stream of packets, and generate a special packet, the special packet containing information to identify which packet in the first stream of packets was encrypted with each control word generated by the plurality of CASs, wherein the first encrypter comprises a physical component module in the head end comprising the physical equipment; and a first decrypter having a secure micro to receive the special packet and configured to decrypt the second stream of packets using the information in the special packet.
1. A subscriber television system comprising: a plurality of conditional access systems (CASs) configured to each supply a control word to a first encrypter for use by the first encrypter to encrypt a first stream of packets with each of the control words, wherein the plurality of CASs are provided by physical equipment in a head end of the subscriber television system, the physical equipment including a random control word generator for providing the control word, wherein each of the control words is generated from information contained in an entitlement control message and information from authorization information, the authorization information stored in a set-top box in the subscriber television system, wherein the entitlement control message comprises frequently changing decryption information; the first encrypter configured to: encrypt the first stream of packets to produce a second stream of packets, each packet of the first stream of packets corresponding to a single encrypted packet in the second stream of packets, and generate a special packet, the special packet containing information to identify which packet in the first stream of packets was encrypted with each control word generated by the plurality of CASs, wherein the first encrypter comprises a physical component module in the head end comprising the physical equipment; and a first decrypter having a secure micro to receive the special packet and configured to decrypt the second stream of packets using the information in the special packet. 2. The system of claim 1 , further comprising: a second encrypter; a selector configured to select packets from the first stream of packets for encryption with the first encrypter using a control word from a first encryption CAS, and to select packets from the first stream of packets for encryption with the second encrypter with the control word from a second encryption CAS; and a multiplexer configured to multiplex packets encrypted with the control word from the first encryption CAS and packets encrypted with the control word from the second encryption CAS.