HK1034390A - Method for transferring data from a head-end to a number of receivers - Google Patents

Description

Method for transmitting data from a head-end device to a plurality of receivers

The invention relates to a method for transmitting data from a head-end to a plurality of receivers using digital broadcast signals, each of said receivers comprising a descrambler for descrambling a received digital transport stream.

An advantage of using a digital broadcast signal, such as a DVB signal, to transmit data to one or more receivers is that available receivers with descramblers can be used to transmit data from the head-end to the receivers. However, this method normally does not allow data to be transmitted in a secure and secret manner, since all receivers listening to the digital transport stream have access to the data.

It is an object of the invention to provide a method of the above-mentioned type in which the confidentiality and security of the data transmission can be provided to each receiver.

There is provided a method of the invention of the type set forth above comprising the steps of: sending a message from the head-end to each receiver that needs to transmit data to them, said message comprising a key that is unique to the respective receiver, loading the key into the decryptor of the respective receiver, providing a table, including a unique key and a corresponding address of a corresponding receiver at a head-end device, providing data packets having at least one individual address of said receiver, inserting said data packets into transport packets of a digital transport stream, selecting a key from the table based on the address of the data packet, encrypting the transport packet using the selected key, broadcasting the digital transport stream, the digital transport stream is received at one or more receivers, and encrypted transport packets of the digital transport stream are only decrypted at the receivers having a unique key for encrypting the encrypted transport packets.

In this way a method is obtained in which each receiver attempting to descramble the broadcast signal will fail in descrambling the signal intended only for reception by a receiver having a unique key for scrambling a transport packet in which a data packet is inserted that is intended to be received by this receiver. As a result, the required confidentiality and security of the data transmission between the head-end device and the receiver can be obtained.

In a preferred embodiment for transmitting data packets to two or more receivers, data packets for different receivers are inserted in different transmission packets, each of said transmission packets being encrypted using a unique key corresponding to the respective data packet's individual address.

In this way, a block of receivers requesting transmission of data is provided with data transmission having privacy and security.

The invention will be further described with reference to the accompanying drawings, in which an embodiment of the invention is shown in principle.

In the preferred embodiment, the method is used to transmit data requested by the receiver from the internet to the receiver on a digital broadcast signal or digital transport stream, thereby obtaining an internet connection for high speed transmission of data to the receiver according to the internet protocol. The described method can however also be used to transmit data to the receiver either at the request of the receiver or when initiated by the head-end in another way.

A DVB system is schematically shown by way of example and comprises a head end device 1, hereinafter referred to as a head end device, and a large number of users having receivers 2, only one of which is shown. The receiver 2 comprises a descrambler 3 cooperating in the usual way with a smart card 4. The descrambler 3 is used to descramble DVB services requiring a subscription. The receiver 2 is connected to the internet 5 in a manner not shown and may be, for example, a well-known modem. If the receiver 2 requests to download data, the data will be transmitted to the receiver 2 through the head-end 1 using a broadcast signal in the following manner.

According to the internet protocol, the data comprises an IP or MAC address of the receiver requesting the data to be transmitted to the receiver 2. Each head-end device 1 sends a so-called Entitlement control message or ECM with a control word or key that is unique to the receiver 2 for which it receives data packets with an individual address, e.g. an IP or MAC address. This message is encrypted using an individual key stored in the smart card 4. The unique key with the corresponding individual address at the head-end 1 is stored in table 6. At the receiver 2 to which the ECM is sent, the smart card 4 decrypts the received message using its individual key in order to obtain the unique key. The decrypted key is loaded into the decryptor 3 for future use.

At the head-end 1, data packets of a particular receiver 2 requesting transmission of data are inserted in transport packets of the digital transport stream. Generally, data packets are larger than transport stream packets, so the data packets are unpacked and then inserted into a batch of transport stream packets. Before encrypting the transport stream packets containing the data packets, the head-end checks the IP or MAC address and selects the corresponding unique key from table 6 for encrypting the transport stream packets.

Each receiver 2 listening to the digital broadcast signal tries to decrypt the transport stream packets of the digital transport stream, wherein of course this decryption process is successful only for receivers 2 having a unique key for encrypting the transport stream packets. In this way only one receiver 2 can decrypt the encrypted transport stream packet to obtain an IP data packet.

From the above, it is clear that the operational result of the described method is the transmission of data with confidentiality and security for each receiver 2 requesting data transmission. In addition, this transmission with privacy and security is done using existing DVB or MPEG encryption and decryption equipment.

In general, a batch of receivers 2 requests data for transmission. This is not problematic because the head-end 1 can provide a table 6 that provides the key/address combination for each receiver 2 that requests transmission of data. The capacity of the digital broadcast signal is large enough to transmit IP data packets to a large number of receivers 2. Since the IP data packets for each particular receiver are to be inserted into a collection of transport packets, only those transport packets that use a unique key applicable to that particular receiver are encrypted, the data transmission is still done in a secure and secure manner.

The data packets may be inserted in transport stream packets of a digital transport stream that is used only for transporting data. Alternatively, the data packets may be inserted in transport stream packets of a DVB transport stream, since the capacity of such a transport stream is much larger than the capacity required for transporting video information.

Although in the preferred embodiment the method is used to transmit IP data packets, the described method can also be used to transmit data from other sources than the internet. It should furthermore be noted that instead of an ECM other types of messages may be used to transmit a unique key to the receiver.

Claims (5)

1. A method of transmitting data from a head-end to a plurality of receivers using a digital broadcast signal, each of said receivers including a descrambler for descrambling a received digital transport stream, said method comprising the steps of: sending a message from the head-end to each receiver that needs to transmit data to them, said message comprising a key that is unique to the respective receiver, loading the unique key into the descrambler of the respective receiver, providing a table, including a unique key and a corresponding address of a corresponding receiver at a head-end device, providing data packets having at least one individual address of said receiver, inserting said data packets into transport packets of a digital transport stream, selecting a key from the table based on the address of the data packet, encrypting the transport packet using the selected key, broadcasting the digital transport stream, the digital transport stream is received at one or more receivers, and encrypted transport packets of the digital transport stream are only decrypted at the receivers having a unique key for encrypting the encrypted transport packets.

2. A method according to claim 1, wherein for transmitting data packets to two or more receivers, data packets intended for different receivers are inserted into different transport packets, each of said transport packets being encrypted using a unique key corresponding to the respective data packet's individual address.

3. A method according to claim 1 or 2, wherein each receiver is adapted to request transmission of specific data from the head-end.

4. A method according to claim 1, 2 or 3, wherein the head-end and the receivers are connected to a network, such as the internet, wherein one or more receivers request transmission of data from the network, wherein the requested data is provided to the head-end in the form of data packets together with the address of the requesting receiver and the head-end transmits the data packets inserted in the transport packets of the digital broadcast stream to said one or more receivers.

5. A method according to any one of the preceding claims, wherein the digital transport stream is a DVB transport stream.