EP1329050A2

EP1329050A2 - Module for secure transmission of data

Info

Publication number: EP1329050A2
Application number: EP01988996A
Authority: EP
Inventors: Christophe Genevois; Jean Luc Duhamel
Original assignee: SCM Microsystems GmbH
Current assignee: Identiv GmbH
Priority date: 2000-10-27
Filing date: 2001-10-29
Publication date: 2003-07-23
Also published as: WO2002035763A3; WO2002035763A2; US20040221156A1; DE10053390A1

Abstract

The invention relates to a module for secure transmission of data in a computer network. The module has a bi-directional interface with a computer connected to the network enabling the module to exchange packets, commands and messages with the computer via said interface. The module also comprises an interface to a smart card containing an identification key. A filter logic circuit is arranged in the module. Said circuit filters out authorization messages from the data packets which are received by the computer via the network and transmitted to the module via the bi-directional interface. The module further comprises a processor having a memory for controlling the module and which calculates at least one cryptographic key by means of the authorization messages and the identification key contained in the smart card, in addition to a decryption logic circuit which can separate the header from the contents of the data packets, decode the contents of the data packets by means of the cryptographic key which is calculated by the processor and is associated with the decryption method carried out in the hardware of the logic circuit, and can reincorporate the header into the decrypted content of the data packets, whereby the data packets are redirected to the computer via the bi-directional interface.

Description

Module for the secure transmission of data

The invention relates to a module for the secure transmission of data in a computer network, in which data is transmitted according to a network protocol, the data being organized in data packets, consisting of a header and a content that can be encrypted. The invention also relates to a system for the secure transmission of data between two computers which are connected to one another by a computer network. Secure data transmission in computer networks is becoming increasingly important. As the boundaries between the individual media terminals such as radio and television receivers and PCs are becoming increasingly blurred, in particular for the provision of chargeable services, for example via the Internet, e.g. Digital television (DVB = Digital Video Broadcasting) Wanted opportunities to distribute large amounts of data over a wide area, to which access can be specifically permitted or denied.

The object of the invention is to provide a module for secure data transmission in a computer network, which offers the highest level of security with high data throughput and easy connection to existing computers.

For this purpose, a module of the type mentioned at the beginning is provided: a bidirectional interface to a computer connected to the network, the module via the interface with the computer

A processor can exchange data packets, commands and messages, an interface to a smart card on which an identifier is stored, a filter logic circuit that filters out authorization messages from the data packets received from the computer via the network and forwarded to the module via the bidirectional interface with memory for controlling the module, which calculates at least one cryptographic key by means of the authorization messages and by means of the germination stored in the smart card, a decryption logic circuit which can separate the header from the content of the data packets, the content contained in the data packets by means of the processor calculated cryptographic key, which interacts with a decryption method implemented in the hardware of the logic circuit, can decrypt and attach the header again to the decrypted content of the data packets, the data packets then using the bid directional interface to the computer.

Such a module has considerable advantages: On the one hand, the decryption of the data in a hardware logic circuit takes place very quickly, so that large amounts of data can be processed in a short time, which is particularly important in DVB. On the other hand, the module is as

Hardware is secured much better against unauthorized access (hacking) to the encrypted data and the keys themselves than a Software decoder in an open, unsecured environment, as represented by a computer.

The object of the invention is also achieved by a module of the type mentioned at the outset, which provides: a first interface to a computer network, via which the module can receive data packets from the computer network, a second interface to a computer, via which the module can send data packets to the computer, - an interface to a smart card on which an identifier is stored, a filter logic circuit that filters authorization messages from the data packets received from the network and forwarded to the module via the first interface, a processor with Memory for controlling the module, using the authorization messages and the ones stored in the smart card

Identifier calculates at least one cryptographic key, a decryption logic circuit that can separate the header from the content of the data packets, can decrypt the content contained in the data packets by means of the cryptographic key calculated by the processor, which interacts with a decryption method implemented in the hardware of the logic circuit Can attach the header again to the decrypted content of the data packets, the data packets then being routed to the computer via the second interface. With this configuration, it is possible to easily connect the module to the connection to the computer network, so that no additional interface on the computer is required.

The invention is described in more detail below on the basis of preferred embodiments. Reference is made to the accompanying drawings, in which:

1 shows a block diagram of a first embodiment of a module according to the invention;

FIG. 2 shows a block diagram for an application of the module from FIG. 1 in a network; FIG.

3 shows a block diagram of a second embodiment of a module according to the invention; and

4 shows a block diagram for one possible application of the module from FIG.

3 show in a network. 1 shows a module 10 according to the invention which is provided for conditional access (CA = Conditional Access) to media content from a network, for example the Internet. In this network, data packets are created according to a network protocol. eg the well-known Internet Protocol (IP), whereby the media content in the packets can be encrypted. In this embodiment, the module 10 is designed as a plug-in card for a PCMCIA slot in a computer, advantageously a laptop 12, which is connected to a computer network 34. The module 10 itself contains a bidirectional interface module 14, which for the sake of simplicity is referred to below as a bidirectional interface 14, a processor 20 with memory and an interface module 22 to a slot 24 (not shown) for a smart card 26 , which in the following are called the interface for a smart card for the sake of simplicity. The processor 20 is connected via the control lines 25 to all other modules of the module and controls the functions of the module 10. The bidirectional interface 14 is connected via the bus 15 to an interface module (not shown) in the computer 12. The module can receive data packets received from the computer via the network 34 via the bus 15 and, after decryption, pass them on to the computer 12. It is also conceivable that the module 10 can communicate with the computer 12 via the bus 15, which makes it possible to operate the module 10 from the computer 12. The interface 15 can forward data to a filter logic circuit 16 via a connection 30 and exchange data with a decryption logic circuit 18 via a second connection 32.

2 shows a section of a network 40 to which the computer 12 is connected. The computer of a service provider 42 is connected to the network 40 and in this embodiment provides digital television (DVB = Digital Video Broadcasting).

The function of the module 10 is described below using the example of a DVB transmission from the service provider 42 to the customer's computer 12. The service provider 42 provides a DVB signal 44. This signal is intended to be sent over the network 40 in data packets in such a way that only certain authorized customers are able to receive and read this signal. For this purpose, the signal is packaged in data packets in a known manner and the content of the data packets is encrypted in an encoder 46 (also called a scrambler) with changing cryptographic keywords that are generated in a word generator 48. The information required to decrypt the data packets is sent as so-called Entitlement Control Message (ECM) and as Entitlement Management Message (EMM) together with the signal in the data packets. The EMMs contain user-specific data that give a certain customer or a certain group of customers access to certain Enable programs (pay per channel) or for certain programs (pay per view). The assignment to a specific customer or a specific customer group is established by an identifier, which can be stored in the smart card, for example. The service provider therefore has the corresponding customer data in a database 50 so that the EMMs can be sent automatically. The ECMs, on the other hand, contain program-specific data, namely the key words by means of which the data packets can be decrypted again. To make it even more difficult to break up the encryption without authorization, the keywords are changed frequently during the broadcast. The ECMs are sent much more frequently than the EMMs, since the user-specific data rarely change compared to the keywords.

The data packets are sent via the network 40, which can be, for example, the Internet, a private network or a company-internal intranet. They are given a header specific to the respective network protocol, which contains certain information that is important for transmission to the network. With the Internet protocol IP this can e.g.

Information about the version of the protocol, the header length, the type of service, the total length of the data packet, the lifespan of the packet, a

Checksum, the type of the higher-level transport protocol (e.g. TCP UDP), the

Computer source address and the computer destination address.

The computer 12, which e.g. Via a modem 46, as shown, can be connected to the network via a network card or in some other way, receives the data packets and forwards them to module 10 without further processing via the PCMCIA interface. The data packets can be passed on both to the filter logic circuit 16 and to the decryption logic circuit 18. The filter logic circuit filters out any EMMs and ECMs contained in the data and passes them on to the processor 20 via the bus 25.

When the processor 20 receives an EMM which is intended for the customer identified by the identifier contained in the smart card 26, it loads the information contained therein into the memory and holds it there until it is replaced by more current information from a new one EMM can be overwritten. This information includes, for example, the authorization to be able to access a specific program or a specific program. If the processor 20 then receives ECMs relating to this particular program or program, it can use this information and the identifier stored in the smart card 26 from the ECMs to obtain the cryptographic keys for decrypting the content of the data packets from which the program is made exists, calculate. The processor 20 forwards the calculated keys to the decryption logic circuit 18. The decryption logic circuit 18 includes a header logic circuit, not shown in detail, that the

Separates the header of the data packets from the content and stores the header on the bus 25 in the memory. The header logic circuit can be used with others Embodiments of the invention may also be part of the interface module 14, so that the data to the filter logic circuit 16 via the connection 30 only consist of the content of the data packets. The decryption logic circuit 18 uses the calculated keys to decrypt the content of the data packets using an encryption method implemented in their hardware and to return the decrypted content to the interface again. The header logic circuit then retrieves the stored header from the memory and adds it to the now decrypted content of the data packet, so that the packet is complete again. and forwards this via the bidirectional bus 15 to the computer 12, in which further processing can take place in the usual way. The content of data packets for which the customer does not have access authorization cannot be decrypted by the decryption logic circuit 18. These data packets are either not sent to the interface at all or are not encrypted

Computer 12 forwarded so that they can not be processed by the computer 12.

In the opposite way, the interface 14 can be generated by the computer 12 via its interface module (not shown) and the bus 15 in the computer

Receive data packets with unencrypted content, encrypt this content and send it back to the computer 12 via the interface 14 and the bus 15, the computer then sending the packets over the network. As can be seen from the description, the invention offers the advantage of being easy to use, since the computer can be equipped with access to the offers of the service provider without opening the computer or changing its hardware in any other way. In comparison to a pure software solution, the hardware implementation of the encryption logic offers the advantage that the processor of the computer is not additionally burdened with decryption or encryption. This also means a considerable speed advantage, which is essential for a smooth display, especially with the large amounts of DVB data.

In addition, such a module is independent of the respective operating system of the computer, since it works purely at the protocol level of the network. This means that the module has a much larger application area than a purely software-based decryption system.

The main advantage over previous software-based security systems (e.g. in software-implemented conditional access systems) is that the keys and access authorization messages (ECM, EMM) cannot be spied on via the network of "hackers".

A second embodiment of the invention is shown in FIG. 3. The module 100 has a first interface 160 to a computer network 140 and a second interface 162 to a computer 1 12. Both interfaces work according to the same protocol and on the same physical layer, for example Ethernet, so that the module 100 directly into the network line 150 the computer network 140 and the computer 1 12 can be switched on. The interfaces 160, 162 in the module 100 merely take on the function of connecting to the network, comparable to a network card in a computer. The interfaces 160 and 162 are connected to an IP switch 164, to which a CA unit (CA = Conditional Access) 110 is coupled, which essentially corresponds to the module 10 described in connection with the first embodiment.

The data packets received from the network 140 are passed through the IP switch 164. In the IP switch 164, data packets received via the first interface 160, which are intended for the CA unit 110 based on their IP address, are filtered out and fed to the CA unit 110, which decrypts the data content of the packets as previously described and returns the data packets. The other data packets, as well as the data packets already decrypted by the CA unit 110, are forwarded by the IP switch 164 to the second interface 162, which sends them to the computer 112 via a network connection line 152. In addition, the CA unit 1 10 can have a connection 166 to the second interface 162, by means of which the module 100 can be controlled by the computer 1 12 via the network line 152. The computer thus already receives the data packets transmitted in encrypted form by the service provider 42, so that it can proceed further as with the offers distributed in the network 140 without access restrictions. The module 100 can also be completely transparent to the other data packets, i.e. the network connection can run undisturbed, as if the module 100 were not present at all.

A particular advantage of this embodiment is that the secure access option can be created even more easily. There is no need for an additional interface on the computer 112, since the module 100 is looped into the existing network connection line 150.

In addition, a subnetwork, that is to say a plurality of interconnected computers, can also be provided with the access option in this way.

Of course, the application of the invention is not limited to use with DVB. Since each module both encrypted the content

Decrypting data packets as well as encrypting unencrypted content can be done with the help of the described modules, in principle any content to be protected, e.g. emails that are sent in packets according to a network protocol, securely between two or more computers, or between different computers Transfer subnets of a network safely. An exemplary arrangement is shown schematically in FIG. 4, where the modules 200 act as a kind of lock between a secure subarea 270, for example a company's internal network, and an unsecured public area 272 of the network. In this case, each computer 212 or each sub-area of the network 270 from which access to the saved data should be possible is connected to the public sub-network via a module according to the invention. The data to be protected is sent unencrypted within the secure subareas 270, outside, ie in the unsecured public area 272 of the network, the data packets are only on the way with encrypted content. The module according to the invention thus fulfills the function of a “hardware firewall” in an efficient manner.

Claims

claims

1. Module for the secure transmission of data in a computer network, in which data is transmitted according to a network protocol, the data being organized in data packets, consisting of a header and a content that can be encrypted, with a bidirectional interface a computer connected to the network, the module being able to exchange data packets, commands and messages via the interface with the computer, - an interface to a smart card, on which an identifier is stored, a filter logic circuit which consists of the data from the computer via the Network messages received and passed on to the module via the bidirectional data packets, filtering authorization messages, a processor with memory for controlling the module, which is stored by means of the authorization messages and by means of those stored in the smart card

Identifier calculates at least one cryptographic key, a decryption logic circuit that can separate the header from the content of the data packets, can decrypt the content contained in the data packets by means of the cryptographic key calculated by the processor, which interacts with a decryption method implemented in the hardware of the logic circuit Can attach the header again to the decrypted content of the data packets, the data packets then being returned to the computer via the bidirectional interface.

2. Module according to claim 1, in which the decryption logic circuit is designed such that it contains the content of data packets that were generated in the computer and were received by the module via the bidirectional interface, with the aid of a stored by the processor in the smart card Identifier calculated cryptographic key, which interacts with an encryption method implemented in the hardware of the logic circuit, can encrypt, the data packets then being returned via the bidirectional interface to the computer, which provides them with a header and forwards them to the network.

3. Module for the secure transmission of data in a computer network, in which data are transmitted according to a network protocol, the data being organized in data packets, consisting of a header and a content that can be encrypted, with a first interface a computer network via which the module can receive data packets from the computer network, a second interface to a computer via which the module can send data packets to the computer, an interface to a smart card on which an identifier is stored, a filter logic circuit that consists of the data packets received from the network and forwarded to the module via the first interface

Filtered out authorization messages, a processor with memory for controlling the module, which by means of the Authorization messages and by means of the identifier stored in the smart card calculates at least one cryptographic key, a decryption logic circuit that can separate the header from the content of the data packets, the content contained in the data packets by means of the cryptographic key calculated by the processor, which is associated with a hardware decryption method implemented in the logic circuit cooperates, can decrypt and can attach the header again to the decrypted content of the data packets, the data packets then being routed to the computer via the second interface.

4. Module according to claim 3, in which the first and the second interface are each bidirectional and the decryption logic circuit is designed such that it can separate the header from the content of data packets that have been generated in the computer and received via the second interface, the content contained in the data packets with the help of a cryptographic key calculated by the processor using the identifier stored in the smart card, which interacts with an encryption method implemented in the hardware of the logic circuit, can encrypt and can attach the header to the encrypted content of the data packets again , the data packets then being routed to the network via the first interface.

5. Module according to claim 3 or 4, in which a selection device is provided between the module and the two interfaces, which forwards a data packet from one of the interfaces to the module when it recognizes on the basis of the information in the header that the data packet is to be removed. or is provided for encryption in the module and which forwards the data packet to the other interface if it recognizes from the information in the header that the data packet is not intended for decryption or encryption in the module.

6. Module according to one of the preceding claims, for the reception of a digital television program (DVB), in which the authorization messages filtered by the filter logic circuit from the data packets, on the one hand, access management messages (EMM), which contain user-specific access authorization information, and on the other hand, access control messages (ECM), which contain shipment-specific access authorization information and in which the processor stores the information in the memory and calculates the cryptographic key using the EMMs, the ECMs and the identifier stored in the smart card.

7. Module according to one of the preceding claims, which is provided with a memory for asynchronously arriving data packets and has a clock generator, by means of which it can pass on the stored data packets synchronously after decryption or encryption.

8. Module according to one of the preceding claims, characterized in that the data packets are emails.

9. System for the secure transmission of data between computers which are connected to one another by a computer network in which data are transmitted according to a network protocol, characterized in that at least two computers of the computer network are connected to a module according to one of the preceding claims are.