WO2009090046A1

WO2009090046A1 - Secure data communication

Info

Publication number: WO2009090046A1
Application number: PCT/EP2009/000175
Authority: WO
Inventors: Stephan Spitz; Walter Hinz; Erich Englbrecht; Thomas Palsherm
Original assignee: Giesecke & Devrient Gmbh
Priority date: 2008-01-15
Filing date: 2009-01-14
Publication date: 2009-07-23
Also published as: DE102008004384A1; EP2245834A1

Abstract

The invention relates to a method for allowing secure data communication between a terminal (100) and a data processing device (200). In said method, a portable data carrier (10) that can be connected to the terminal (100) receives a command data message comprising command data of the terminal (100) for the data processing device (200) (S1). A command data forwarding message is then generated in the data carrier (10) according to a secure communication protocol (S2, S3) before a secure communication client device (68) of the data carrier (10) sends the generated command data forwarding message to a secure communication server device (210) of the data processing device (200) according to the secure communication protocol (S4). This allows the data processing device (200) to be easily and securely maintained from a distance by the terminal (100), regardless of the position of the terminal (100) and the system environment thereof.

Description

S i c h e d a t e c o m m i n i k a t i o n

The present invention relates to a method for secure data communication between a terminal and a data processing device.

For remote maintenance of a data processing device, an administrator is faced with the task of providing a secure data communication connection from a terminal to the data processing device via a generally insecure network, eg. As the Internet, build. In the context of the present invention, a secure data communication connection is understood as meaning a data communication connection in which the data processing device, preferably when establishing the connection, authenticates to the terminal, the terminal or a user of the terminal authenticates itself to the data processing device and the following data communication is encrypted is carried out.

For remote maintenance of Unix or Linux systems, the so-called "Secure Shell" (SSH) provides a corresponding communication protocol. But there are already implementations of SSH on other platforms. The SSH protocol supports authentication of the data processing device in the role of the "server" in relation to the terminal in the role of the "client" by means of an authentication key of the server, which is also called a host key. To encrypt the data to be transmitted, the client and the server exchange a secret transport key, eg by means of the Diffie-Hellman key exchange method, which during data communication is stored at each of the client and the server. The encryption itself then takes place according to a known symmetric encryption method, eg 3DES, IDEA, AES or the like. The integrity of the transmitted data is ensured by a checksum. The SSH protocol further supports an authentication of the client or a user of the client with respect to the server, for example by means of a password, and finally provides various logical channels for now bi-directionally authenticated and encrypted data communication.

The client can check the received authentication key by comparing it with a corresponding copy stored locally at the client. Of course, the client must already know the authentication key of the server. It is also possible that the authentication key of the server is provided by means of a certificate of a certification authority, which can then be checked by the client. If the client accepts an authentication key of the server which he does not know and which he can not check, there is a risk that a third instance behind the alleged server merely pretends to be the server. At the same time, this instance can pretend to be the client to the actual server and thereby track the entire subsequent data communication between client and server unencrypted or decrypted for the third instance.

A data communication established in the foregoing manner between a terminal such as a user's personal computer (PC) and a server becomes vulnerable when, for example, the secret transport key stored on the PC during data communication is spied out. It is also possible that a stored in the PC Host key of a server is changed by invaded in the PC malicious code such that a third instance can issue when rebuilding a data communication connection by the client as a server, without this being recognized by the client.

Furthermore, an SSH-secured data communication connection to a server can only be set up by such clients on which a corresponding security communication-Qient application is implemented. However, this is true for a large class of terminals, e.g. Mobilfunkend- rate, handhelds and the like, usually not the case.

It is therefore the object of the present invention to propose a method which allows a terminal in a flexible manner to establish a secure data communication connection to a data processing device.

This object is achieved by a method and a portable data carrier having the features of the independent claims. Advantageous embodiments and further developments are given in the dependent claims.

The invention is based on the basic concept of providing the functionality of a security communication client device on a portable data carrier which can be connected to the terminal device and the data processing device for data communication.

Accordingly, in the method according to the invention for providing secure data communication between a terminal and a data processing device, a portable data carrier which is a security communication client device, provided and connected to the terminal and the data processing device. The data carrier receives a command data message, which comprises command data of the terminal for the data processing device, according to an Internet communication protocol from the terminal. A command data forwarding message is then created in the data carrier according to a security communication protocol based on the command data from the received command data message. The security communication client device of the data carrier then sends the command data forwarding message according to the security communication protocol to a security communication server device of the data processing device.

By providing the security communication client device on the portable data carrier, secure data communication can be established between any terminal and a data processing device comprising a security communication server device. The terminal itself does not require a security communication client device for this purpose. Secure protocol conversion between the Internet communication protocol, according to which the command data is sent from the terminal to the data carrier, and the security communication protocol, according to which the security communication client device forwards the created command data forwarding message to the data processing device, takes place in the portable data carrier , Furthermore, secret data in connection with the data communication between the terminal and the data processing device, for example a secret transport key for encrypting the data communication, can be securely stored on the data carrier instead of on the terminal. The disk can be against Attacks by means of malicious code and the like are better protected than the terminal and can safely store the secret data in a protected storage area of the data carrier from the access of third parties. Finally, authentication data that enable unambiguous authentication of the server with respect to the client, for example a host key of the server, can also be securely and verifiably stored on the data carrier.

The terminal can remotely control the data processing device by means of the method. The desired security functionalities - mutual authentication and encryption of the data communication - leading to remote control over an insecure communication network, such as the Internet. The Internet, needed to not compromise the security and integrity of the computing device, are all provided by the secure communications client device on the media and by the security communications protocol supported by that device.

Preferably, after connecting the data carrier to the terminal, a data communication connection is made between a web browser of the terminal and a web server of the data carrier in accordance with the Internet communication protocol. Thereafter, the web server of the volume receives the command data message about the established data communication connection from the web browser of the terminal according to the Internet communication protocol. In this way, a user of the terminal is provided with a data input and output interface to the security communication client device on the data carrier, which supports data communication between the terminal and the data carrier in a simple and standardized manner. Nearly Each device has a web browser or can be easily equipped with it.

According to a preferred embodiment of the method, the data carrier comprises a switching device. When creating the command data forwarding message, the command data message is transferred from the web server to the switch. In turn, the switch extracts the command data from the command data message and passes the extracted command data to the security communications client device. The switching device acts as a bridge between the web server and the security communication client device on the data carrier, supports an implementation of the various communication protocols and thus ensures a simple and secure data communication between the terminal and the data processing device. The security communication gateway preferably transforms the command data extracted and transferred by the switching device from the command data message into a command data forwarding message according to the security communication protocol. That is to say, the switching device is set up to transfer the extracted command data of the security communication client device as user data, ie without a specific protocol frame and the like, and the security communication client device is for transforming the command data into the command data forwarding message according to the security communication protocol set up, ie for creating a data message in accordance with the SicherheitskommunikationprotokoU, which includes the command data ais useful data. However, such a transformation can also be made wholly or partly by the switching device. An implementation between the Internet communication protocol and the Security communication protocol is thus carried out in cooperation between the web server, the switching device and the security communication client device on the disk safely.

A portable data carrier according to the invention therefore comprises at least one communication interface, a web server application, a security communication client application and a switching device. In this case, the web server application is set up to receive a command data message transmitted by a web browser of a terminal connectable to the data carrier in accordance with an Internet communication protocol and comprising command data of the terminal for a data processing device, and to forward the received command data message to the switching device to hand over. The switch is set up to extract the command data from the command data message and to pass it to the security communication QI application. The security communication client application is in turn configured to send a command data forwarding message, which comprises the command data, to a security communication server application of the data processing device connectable to the data carrier via the at least one communication interface in accordance with the security communication protocol.

Typically, the security communications client application receives on the volume a response data message comprising response data for the terminal according to the security communication protocol from the security communications server application of the computing device in response to the command data forwarding message and transmits the response data message to the switch. The Switching device in turn extracts the response data from the response data message and passes the response data to the web server application. Finally, the web server application sends a reply data forwarding message comprising the response data according to the internet communication protocol in response to the command data message to the web browser of the terminal. In this way, a complete data communication between the terminal and the data processing device is defined.

The switching device is preferably set up to at least partially transform the response data into a response data forwarding message in accordance with the Internet communication protocol and to transmit the response data in the form of the response data forwarding message already protocol-transformed to the web server. In this direction of the data communication, from the data processing device to the terminal, the switching device essentially assumes the task of protocol conversion. However, it is also possible for components of the web server to assume this task of integrating response data transmitted by the switching device as user data into a protocol-related response data forwarding message.

Preferably, the security communication client application is embodied as an SSH client application which supports the SSH communication protocol as a security communication protocol. Accordingly, the command data forwarding message and the reply data message are sent between such a client application and a correspondingly established security communication server application in the form of an SSH server application according to the SSH communication protocol. This standardized protocol supports all desirable security features, eg a two-sided authentication and an encrypted data transmission of data protected by a hash value integrity-protected. Other security communication protocols may however be used.

The command data message and the response data forwarding message between the terminal's web browser and the data carrier's web server are preferably sent in accordance with the HTTP or HTTPS communication protocol. The latter also allows encrypted data communication on the part of the data communication link between the web browser and the web server. Other Internet communication protocols may also be used.

SSH and HTTP are protocols of an application layer, preferably the application layer according to the OSI layer model (layer 7 of FIG. 7) or optionally also the application layer according to the TCP / IP layer model corresponding to layers 5-7 of the OSI layer model.

The portable data carrier is preferably designed as a chip card, (U) SIM mobile radio card, USB token, mass storage card or the like.

The invention will now be described by way of example with reference to the accompanying drawings. Show:

Figure 1 shows a preferred embodiment of an inventive

Data carrier; and Figure 2 involved in a preferred embodiment of the method according to the invention components.

With reference to FIG. 1, a data carrier 10, which is shown here as a chip card, comprises a communication interface 20, a processor (CPU) 30 and a number of memories 40, 50 and 60. The communication interface 20 is in the form of a contact field in accordance with ISO / IEC 7816 trained and serves the disk 10 for communication with external devices, eg with a personal computer via a card reader or with a mobile terminal. The communication interface 20 may also be of another standard, e.g. USB or SD standard, or proprietary. It is also possible that the data carrier 10 alternatively or additionally a contactless communication interface (not shown), e.g. an antenna coil.

In a non-volatile, non-rewritable ROM 40, an operating system (OS) 42 controlling the data carrier 10 is stored. A volatile, rewritable RAM memory 50 serves as a working memory and a non-volatile, rewritable flash memory 60 is used for storing data and applications, eg. As a web server application 62, a switching device 64 and a security communication client application 68, which is designed here as an SSH client application. The respective applications will be described in more detail with reference to FIG. It is possible to store the operating system 42 or parts thereof in the flash memory 60, which alternatively may be embodied as EEPROM memory.

A method for secure data communication between a terminal 100, eg a mobile radio terminal, and a data processing device. Device 200, for example a personal computer (PC), will be described below with reference to FIG. At this time, the PC 200 including a Unix operating system is remotely controlled from the terminal 100. That is, a user transmits Unix commands from the terminal 100 to the PC 200, for example, to perform backup operations or the like in the system running on the PC 200, and receives corresponding response commands from the PC 200.

As the data input and output interface on the terminal 100, a web browser 110 is used. For example, an HTML form can be used to provide an input mask, e.g. by means of an HTML form a command line is simulated. By means described below, the HTML page as a result of data communication between the terminal 100 and the PC 200 is dynamically changed and can be used in this way for data output from such data on the web browser, the terminal 100 via the web browser 110 of the PC 200 is receiving.

The terminal 100, e.g. a mobile station, is connected to a data carrier 10, for example, a (U) SIM mobile card, which is inserted into the terminal 100. Other combinations of terminal 100 and data carrier 10 are possible, for example a terminal 100 in the form of a PC, which receives a chip card or a mass storage card by means of a card reader, or a USB token via a standardized USB port.

The data carrier 10 comprises a web server application 62. In a first step S1, the web browser 110 of the terminal 100 establishes a data communication connection to the web server 62 on the data carrier 10, by the HTML page described above, which serves as an input and output mask and which is stored on the data carrier 10, requested by the web browser and then provided by the web server application 62. The data communication between the web server 62 and the web browser 110 takes place in accordance with the HTTP or HTTPS communication protocol. Thus, according to the HTTPS communication protocol, the data transfer is already securely performed on the section between the terminal 100 and the data carrier 10. However, it is possible to implement the data input and output interface in other ways and to perform the data communication between the web server 62 and the web browser 110 according to another communication protocol. Via the input form of the HTML page, a user of the terminal 100 enters a command for the PC 200. The HTML page with the entered command data is sent to the web server 62 by the web browser 110 as a command data message, as mentioned using the HTTP or HTTPS communication protocol.

In step S2, the web server 62 transfers the command data message described above to the switching device 64, which extracts the command data, ie the command for the PC 200 entered in the form, from the command data message and transfers it to the SSH client 68 in step S3. The switch 64 may be configured in various ways. In a Java environment, the switch can be implemented by means of suitable Java servlets. Other ways to build the switch are scripting languages such as PHP, Perl, and the like. Other technologies for dynamically generating HTML content, eg based on the programming languages C / C ++, are also suitable. The switching device 64 essentially extracts the user data, ie the command entered in the form, from the HTML document provided by the web server 62, ie protocol-specific components, such as headers and the like, are removed, and only pure user data is removed to the SSH Client 68, which in turn is arranged to form a command data forwarding message comprising the command data according to the SSH communication protocol and to send in step S4 to the SSH server 210 of the PC 200.

The invention will be explained here with reference to the SSH communication protocol. Any other communication protocol that enables secure data transmission between the data carrier 10 and the PC 200 is also applicable. A first level of the SSH protocol, the "Transport Layer Protocol", relies on a common transport protocol, e.g. TCP, and serves to authenticate the PC 200 in the role of the "server" against the disk 10 in the role of the "client". Furthermore, this level guarantees confidentiality of the data communication by exchanging a secret transport key between the communication partners for encrypting the subsequent data communication and ensures integrity of the transmitted data by providing a checksum.

The server authentication is performed by an authentication key of the PC 200, which is also called "host key". The client, that is to say the data carrier 10, checks the received authentication key by comparing it with a corresponding copy, which is stored securely in the data carrier 10. An attack on the data transfer connection to be set up between the data carrier 10 and the PC 200 is therefore not necessary because it is not possible for a third party to contact the SSH client 68 of the data transfer connection. Carrier 10 to offer a false host key as an alleged server host key, because a comparison of the supposed server host key with the correct host key stored in the disk 10 would detect the attack and it would be a termination of the data transmission connection respectively. The secret transport key negotiated between the SSH client 68 and the SSH server 210 for encrypting the subsequent data transfer is also saved and stored in the memory 60 of the data carrier 10 for non-spyware.

A second level of the SSH protocol, the "User Authentication Protocol", enables authentication of the user of the terminal 100 via the SSH client 68 at the PC 200, e.g. by a password and / or a public key of the user. The password may have previously been transmitted via the HTML form secured in steps S1, S2 and S3 via the web browser 110, the web server 62 and the switching device 64 to the SSH client 68. Finally, a third level, the "Connection Protocol", provides various logical channels for now bi-directionally authenticated and encrypted data communication. For the transmission of data by means of the SSH communication protocol, all transmission technologies are available, e.g. are arranged to transmit transport and switching protocols of the TCP / IP protocol stack, e.g. GPRS, WLAN, Ethernet, UMTS.

The SSH server 210 receives the command data forwarding message, after which the command transmitted therewith is executed in the system running on the PC 200. In step S5, corresponding response data are sent by means of a reply data message according to the SSH communication protocol from the SSH server 210 to the SSH client 68, which transfers this to the switching device 64 in step S6. The switching device 64 again assumes the task of extracting the payload data, that is to say the response data, from the reply data message in the form of the message in accordance with the SSH communication protocol and transferring it to the web server 62 in step S7. At this point, the switching device 64 usually actively acts as a protocol converter by already preparing the extracted user data in the form of HTML code. The switching device 64 integrates this HTML code into the HTML page to be sent from the web server 62 to the web browser 110 as a response data forwarding message in step S8, thereby dynamically modifying it in response to the response data received from the PC 200.

The HTML page sent in step S8 from the web server 62 of the data carrier 10 to the web browser 110 of the terminal 100 is displayed to the user of the terminal 100, followed by another command in the manner described above with reference to steps S1 to S8 the PC 200 can be sent. The method thus enables location-independent and platform-independent remote maintenance of the PC 200 from any terminal 100 as long as it comprises a common web browser 110 and is set up to be connected to the data carrier 10.

Claims

Patent claims

A method of providing secure data communication between a terminal (100) and a data processing device (200), comprising the following steps in a portable data carrier (10) connectable to the terminal (100):

Receiving (Sl) a command data message from the terminal (100) comprising command data of the terminal (100) for the data processing device (200) in the portable data carrier (10) according to an Internet communication protocol; Creating (S2, S3) a command data forward message according to a security communication protocol based on the command data from the received command data message in the portable volume (10);

Sending (S4) the created command data forwarding message by a security communication client device (68) of the portable data carrier (10) to a security communication server device (210) of the data processing device (200) according to the security communication protocol.

2. Method according to claim 1, characterized in that the terminal (100) remotely controls the data processing device (200) by means of the command data.

3. The method of claim 1 or 2, characterized in that receiving the command data message by the data carrier (10) comprises the following steps: Establishing (Sl) a data communication connection between a web browser (110) of the terminal (100) and a web server (62) of the data carrier (10) according to the Internet communication protocol; Receiving the command data message by the web server (62) of the data carrier (10) from the web browser (110) of the terminal (100) via the data communication connection according to the Internet communication protocol.

4. The method according to claim 3, characterized by a switching device (64) on the data carrier (10) and the following steps when creating the command data forwarding message:

Passing (S2) the command data message from the web server

(62) to the switch (64);

Extracting the command data from the command data message by the switch (64) and passing (S3) the

Command data to the security communications client device (68);

Transforming the transferred command data into a command data forwarding message according to the security communication protocol by the security communication client device

(68).

5. The method according to claim 4, characterized by the further steps of: receiving (S5) a response data message which comprises response data of the data processing device (200) for the terminal (100) from the security communication server device (210) in accordance with the security communication protocol the SI- secure communication client device (68) in response to the command data forwarding message;

Passing (S6) the response data message through the security communications client device (68) to the switching device (64);

Extracting the response data from the response data message by the switch (64) and passing (ST) the response data to the web server (62);

Sending (S8) a response data forwarding message comprising the response data in response to the command data message from the web server (62) to the web browser (110) of the terminal (100) according to the Internet communication protocol.

6. The method according to claim 5, characterized in that the switching device (64) at least partially transforms the response data into a response data forwarding message according to the Internet communication protocol and transmits the response data in the form of the response data forwarding message to the web server (62). passes.

7. The method according to any one of claims 1 to 6, characterized in that the security communication protocol and the Internet communication protocol protocols of an application layer, preferably of the OSI layer model, are such that the portable data carrier in the step of creating (S2, S3) a Performs protocol translation between two application layer protocols.

8. The method according to any one of claims 1 to 7, characterized in that the command data forwarding message and the response data message between the security communication client device (68) and the security communication server (210) according to the SSH communication protocol.

9. A method according to any one of claims 1 to 8, characterized in that the command data message and the response data relay message are sent between the web browser (110) and the web server (62) according to the HTTP communication protocol or the HTTPS communication protocol.

10. Portable data carrier (10), comprising at least one communication interface (20), a web server application (62), a security communication client application (68) and a switching device (64), wherein the web server application (62) is established a command data message transmitted by a web browser (110) of a terminal device (100) connectable to the data carrier (10) in accordance with an Internet communication protocol, which command data of the terminal device (100) for a data processing device (200 ) to receive and hand over the received command data message to the switch (64); the switch (64) is arranged to extract the command data from the command data message and to pass it to the security communication client application (68); and - the security communication-Qientapplikation (68) is arranged, a command data forwarding message, which comprises the command data, to a security communication server device (210) via the at least one communication interface (20) connectable to the data carrier (10) data processing device (200) according to a safety communication protocol.

11. The data carrier (10) according to claim 10, characterized in that the switching device (64) is arranged to transfer the extracted command data of the security communication client application (68) as payload data, and the security communication client application (68) is set up To transform command data into a command data forwarding message according to the security communication protocol.

12. Data carrier (10) according to claim 10 or 11, characterized in that the security communication client application (68) is set up, a response data message of the security communication

Server means (210), which includes response data for the terminal (100), to be received in response to the command data forward message according to the security communication protocol and to be passed to the switch (64); - The switching device (64) is arranged to extract the response data from the response data message and to the Web server application (62) to pass; and the web server application (62) is set up, a response data forwarding message comprising the response data in response to the command data message according to the Internet

Communication protocol to the web browser (110) of the terminal (100) to send.

13. Data carrier (10) according to any one of claims 10 to 12, characterized in that the switching device (64) is arranged to transform the response data at least partially in a response data forwarding message according to the Internet communication protocol and the response data in the form of the response data forwarding message to submit the web server (62).

14. Data carrier (10) according to any one of claims 10 to 13, characterized in that the security communication client application (68) is designed as an SSH client application that onsprotocol supports the SSH communication protocol as Sicherheitsskommunikation-.

15. A data carrier (10) according to any one of claims 10 to 14, characterized in that the data carrier (10) is designed as a smart card or as (U) SIM mobile card or as a USB token or as a mass storage card.