DE102020215004A1 - Secure communication link between systems - Google Patents

Abstract

Method and arrangement for providing a secure communication connection between two systems, wherein a first credential for a first system is provided by a second system, wherein the first credential comprises a temporary one-time secret; wherein a one-time endpoint is provided in the second system for receiving the temporary one-time secret sent from the first system; wherein a first (temporary) communication link is established from the first system to the one-time endpoint in the second system based on the temporary one-time secret; wherein a second credential is provided to the first system by the second system, the second credential comprising a persistent secret, the first system writing the persistent secret to a secure storage of the first system; wherein a second (operative) communication link is established from the first system to the second system based on the persistent secret.

Description

The invention relates to a method for providing a secure communication link between systems.

Establishing a secure communication connection between technical systems (e.g. controllers in the field and servers of a building automation system) usually requires the exchange of credentials with which one participant in the connection must authenticate himself so that the other participant accepts him as trustworthy. In principle, however, digital IDs can be copied at will, which is why their use usually contains “secrets” that a communication partner can prove they know and which they keep secret in their own interest, e.g. by storing them in a secure memory that only they can access.

Before it is used for the first time, e.g. when commissioning a new system, the "secret" must be shared between the two communication partners. With this transfer there is a risk of stealing or corrupting the "secret" by an attacker (man-in-the-middle attack).

A separate communication channel, which is not detailed, is usually used to transmit the "secret", since the communication connection to be secured cannot be trusted before the relationship (between the systems) is established.

The object of the present invention is to provide a method for a comfortable and secure transfer of a secret between technical systems.

• Bereitstellen eines ersten Berechtigungsnachweises (z.B. erstes Credential, oder ein erstes digitales Zertifikat) für ein erstes System von einem zweiten System, wobei der erste Berechtigungsnachweis ein vorläufiges Einmalgeheimnis umfasst;
• Bereitstellen eines Einmal-Endpunktes im zweiten System für den Empfang des vom ersten System gesendeten vorläufigen Einmalgeheimnisses;
• Aufbauen einer ersten (vorläufigen) Kommunikationsverbindung vom ersten System zum Einmal-Endpunkt im zweiten System, basierend auf dem vorläufigen Einmalgeheimnis;
• Bereitstellen eines zweiten Berechtigungsnachweises (z.B. zweites Credential, oder ein zweites digitales Zertifikat) für das erste System vom zweiten System, wobei der zweite Berechtigungsnachweis ein dauerhaftes Geheimnis umfasst, wobei das erste System das dauerhafte Geheimnis in einen sicheren Speicher des ersten Systems schreibt;
• Aufbauen einer zweiten (operativen) Kommunikationsverbindung vom ersten System zum zweiten System, basierend auf dem dauerhaften Geheimnis. Beim vorläufigen Einmalgeheimnis und/oder beim dauerhaften Geheimnis kann es sich z.B. um geeignete EV-Zertifikate (Extended Validation Zertifikate) und/oder um geeignete SSL-Zertifikate (Secure Sockets Layer) und/oder um geeignete TLS-Zertifikate (Transport Layer Security) handeln. Bei den technischen Systemen handelt es sich z.B. um zwei Geräte (z.B. IoT-Geräte, d.h. IoT-fähige Geräte) die über das Internet oder über eine Cloud miteinander datentechnisch verbunden werden sollen. Es können aber auch geeignete Feldgeräte über das Internet oder über eine Cloud mit einem Regel- und Steuergerät (z.B. Controller) oder mit einem Cloud-Server (z.B. Server für eine Gebäudeautomatisierung) sicher verbunden werden. Das Verfahren bietet insbesondere Schutz gegen Man-in-the-Middle-Angriffe oder Korrumpierungsversuche von Dritten. Weiterhin bietet das Verfahren Absicherung einer Kommunikationsverbindung gegen Pharming- und Phishingangriffen. Mit Vorteil werden die Berechtigungsnachweise und die Geheimnisse von einer offiziellen vertrauenswürdigen Zertifizierungsstelle (Certification Authority) bereitgestellt. Bei den Berechtigungsnachweisen und/oder bei den Geheimnissen kann es sich z.B. um Schlüssel-Zertifikate und/oder um Signaturen handeln. Mit Vorteil ist die erste Kommunikationsverbindung nur begrenzt gültig (z.B. für eine definierte Zeitdauer). Mit Vorteil wird die erste Kommunikationsverbindung nur für die Herstellung (Inbetriebsetzung) der zweiten (operativen) Kommunikationsverbindung verwendet. Die zweite Kommunikationsverbindung wird als operative Kommunikationsverbindung zwischen den technischen Systemen verwendet. Über die zweite Kommunikationsverbindung werden z.B. Befehle und/oder Daten ausgetauscht. Bei einem Einmal-Endpunkt handelt es sich z.B. um einen Kommunikationsendpunkt, z.B. um einen Port. Ein Port wird üblicherweise mit einer Portnummer identifiziert, für eine Verwendung in den entsprechenden Netzwerkprotokollen (z.B. TCP, UDP). Für einen Einmal-Endpunkt können z.B. dynamische Ports (Dynamic Ports) verwendet werden.

The object is solved by a method for providing a secure communication link between two systems, comprising the following steps:

• providing a first credential (eg, first credential, or a first digital certificate) to a first system from a second system, the first credential comprising a temporary one-time secret;
• providing a one-time endpoint in the second system to receive the temporary one-time secret sent from the first system;
• establishing a first (temporary) communication link from the first system to the one-time endpoint in the second system based on the one-time temporary secret;
• providing a second credential (eg, second credential, or a second digital certificate) to the first system from the second system, the second credential comprising a persistent secret, the first system writing the persistent secret to a secure storage of the first system;
• Establishing a second (operative) communication link from the first system to the second system based on the persistent secret. The provisional one-time secret and/or the permanent secret can be, for example, suitable EV certificates (Extended Validation Certificates) and/or suitable SSL certificates (Secure Sockets Layer) and/or suitable TLS certificates (Transport Layer Security). . The technical systems are, for example, two devices (eg IoT devices, ie IoT-enabled devices) which are to be connected to one another in terms of data technology via the Internet or via a cloud. However, suitable field devices can also be securely connected via the Internet or via a cloud to a regulating and control device (e.g. controller) or to a cloud server (e.g. server for building automation). In particular, the procedure offers protection against man-in-the-middle attacks or corruption attempts by third parties. The method also offers protection of a communication link against pharming and phishing attacks. Advantageously, the credentials and secrets are provided by an official trusted certification authority. The credentials and/or the secrets can be key certificates and/or signatures, for example. The first communication link is advantageously only valid for a limited period (for example for a defined period of time). Advantageously, the first communication link is used only for establishing (starting up) the second (operative) communication link. The second communication link is used as an operative communication link between the technical systems. Commands and/or data, for example, are exchanged via the second communication link. A one-time endpoint is, for example, a communication endpoint, for example a port. A port is usually identified with a port number for use in the appropriate network protocols (e.g. TCP, UDP). For example, dynamic ports can be used for a one-time endpoint.

A first advantageous embodiment of the invention is that the temporary one-time secret can only be used to create the permanent secret. This increases the security of the communication link between the technical systems. Man-in-the-middle attacks on the communication between the technical systems are avoided or made more difficult.

A further advantageous embodiment of the invention is that the temporary one-time secret loses its validity after it has been used for the first time. This also increases the security of the communication link between the technical systems. Man-in-the-middle attacks on the communication between the technical systems are avoided or made more difficult.

A further advantageous embodiment of the invention is that the provisional one-time secret is valid for a defined period of time. This also increases the security of the communication link between the technical systems. Man-in-the-middle attacks on the communication between the technical systems are avoided or made more difficult. The defined period of time is advantageously linked to the provisional one-time secret or permanently assigned. This coupling or assignment is advantageously carried out when the provisional one-time secret is created. However, it is also possible for the defined period of time to be assigned to the temporary one-time secret, e.g. by a service technician, e.g. The defined time period can be, for example, one hour (1 h) or half an hour (0.5 h).

A further advantageous embodiment of the invention lies in the fact that after the provisional one-time secret has been issued, a previously issued permanent secret loses its validity. This also increases the security of the communication link between the technical systems. Man-in-the-middle attacks on the communication between the technical systems are avoided or made more difficult.

A further advantageous embodiment of the invention lies in the fact that after the permanent secret has been issued, a previously issued provisional one-time secret loses its validity. This also increases the security of the communication link between the technical systems. Man-in-the-middle attacks on the communication between the technical systems are avoided or made more difficult.

A further advantageous embodiment of the invention lies in the fact that a permanent secret can only be issued for the first system with a temporary one-time secret issued for the first system. This also increases the security of the communication link between the technical systems. Man-in-the-middle attacks on the communication between the technical systems are avoided or made more difficult.

A further advantageous embodiment of the invention is that after the second (operative) communication connection has been set up, the temporary one-time secret loses its validity. This also increases the security of the communication link between the technical systems. Man-in-the-middle attacks on the communication between the technical systems are avoided or made more difficult.

A further advantageous embodiment of the invention lies in the fact that after the second (i.e. the operative) communication link has been set up, the one-time end point is set (or terminated) in the second system. The one-time endpoint can therefore no longer be used. This also increases security against corruption of the connection between the systems.

A further advantageous embodiment of the invention lies in an arrangement for providing a secure communication connection between two systems, comprising means for carrying out the method according to the invention. The arrangement is advantageously implemented using means and components that are already available for setting up and operating technical systems that communicate via the Internet or via a cloud.

• 1 eine beispielhafte Konfiguration für eine sichere Kommunikation zwischen zwei technischen Systemen,
• 2 ein erstes beispielhaftes Szenario für den Transfer eines Geheimnisses zwischen zwei technischen Systemen,
• 3 ein zweites beispielhaftes Szenario für den Transfer eines Geheimnisses zwischen zwei technischen Systemen,
• 4 eine weitere beispielhafte Konfiguration für eine sichere Kommunikation zwischen zwei technischen Systemen, und
• 5 ein beispielhaftes Flussdiagramm für ein Verfahren zur Bereitstellung einer sicheren Kommunikationsverbindung zwischen zwei technischen Systemen.

The invention and advantageous embodiments of the present invention are explained using the example of the figure below. show:

• 1 an exemplary configuration for secure communication between two technical systems,
• 2 a first exemplary scenario for the transfer of a secret between two technical systems,
• 3 a second exemplary scenario for the transfer of a secret between two technical systems,
• 4 another exemplary configuration for secure communication between two technical systems, and
• 5 an exemplary flowchart for a method for providing a secure Communication connection between two technical systems.

1 shows an exemplary configuration for secure communication between two technical systems S1 and S2. The system S1 can be, for example, an IoT device (Internet of Things) that is to be connected in terms of data technology to the system S2 via the network NW (eg Internet, intranet, cloud, HTTPS network). The system S2 can be, for example, a regulating and control unit (controller) or a server. The server can be implemented (hosted) in a cloud infrastructure, for example. An IoT device can be, for example, an Internet-enabled field device (e.g. sensor, actuator) or an edge gateway. The network NW may be insecure. A secure communication connection KV1 (eg tunnel) should therefore be created between the systems S1 and S2. A secure communication link KV1 can be set up, for example, by system S1 being authenticated by knowing a secret S1G published by system S2 (eg corresponding certificate, signature, digital key). The system S2 advantageously provides a secure end point SE-S1G (port, communication end point) for the communication connection KV1 (eg a suitable transfer protocol). The secret S1G issued by the system S2 is advantageously stored in the system S1 in a secure memory SS1. The secure storage SS1 is advantageously protected by strong encryption, e.g. by AES encryption (Advanced Encryption Standard), advantageously by AES 256.

If a secure communication link KV1 is set up between the systems S1 and S2, then a potential attacker A cannot corrupt or manipulate it. A communication link KV1 secured by a secret S1G thus offers protection against attackers A who do not possess the secret S1G. The technical systems S1 and S2 advantageously include correspondingly suitable processors, memories and means of communication, as well as corresponding software programs.

However, before a secret S1G is used for the first time, it must be shared between the two communication partners S1, S2. If this transfer does not take place securely and reliably, risks can arise with regard to the security of the communication link KV1.

2 shows a first exemplary scenario for the transfer of a secret between two technical systems S1 and S2. The system S1 can be, for example, an IoT device (Internet of Things) that is to be connected in terms of data technology to the system S2 via the network NW (eg Internet, intranet, cloud, HTTPS network). The system S2 can be, for example, a regulating and control unit (controller) or a server. The server can be implemented (hosted) in a cloud infrastructure, for example. An IoT device can be, for example, an Internet-enabled field device (e.g. sensor, actuator) or an edge gateway. The network NW may be insecure. A secure communication connection KV1 (eg tunnel) should therefore be created between the systems S1 and S2. A secure communication link KV1 can be set up, for example, by system S1 being authenticated by knowing a secret S1G published by system S2 (eg corresponding certificate, signature, digital key). However, before a secret S1G is used for the first time, it must be shared between the two communication partners S1, S2.

A separate communication channel KV2, which is not explained in any more detail, is usually used for the transmission of S1G, since the channel KV3 to be protected cannot be trusted before the relationship is established. For example, a service technician could transport the secret S1G (e.g. certificate) on a memory stick (e.g. USB stick, transport memory) TS, receive it by email, but also download it to S1 via a (one-way) secure connection from S2. Even temporary storage when downloading to a non-secured storage NS1 on the system S1 may be problematic, e.g. if an attacker A can gain access to NS1 later.

An attacker A who becomes aware of the secret S1G can exploit it by using it to pretend to be system S1 on system S2 and act with its rights in system S2. This is particularly dangerous, since the loss (or knowledge by third parties) of the secret S1G can even go unnoticed. The attack can be carried out until the S1G secret is changed, which is long after the configuration of the connection has been completed.

During the configuration (installation) of the communication connection KV3, the secret S1G could be at risk during transit (KV2) from the system S2 to the system S1 (e.g. through theft). An attacker A (e.g. one in the middle attacker) could obtain the secret S1G, impersonate system S1 and attack system S2.

3 shows a second exemplary scenario for the transfer of a secret between two technical systems S1 and S2. The system S1 can, for example, be an IoT device (Internet of things) act, which is to be connected in terms of data technology to the system S2 via the network NW (e.g. Internet, intranet, cloud, HTTPS network). The system S2 can be, for example, a regulating and control unit (controller) or a server. The server can be implemented (hosted) in a cloud infrastructure, for example. An IoT device can be, for example, an Internet-enabled field device (e.g. sensor, actuator) or an edge gateway. The network NW may be insecure. A secure communication connection KV1 (eg tunnel) should therefore be created between the systems S1 and S2. A secure communication link KV1 can be set up, for example, by system S1 being authenticated by knowing a secret S1G published by system S2 (eg corresponding certificate, signature, digital key). However, before a secret S1G is used for the first time, it must be shared between the two communication partners S1, S2.

The proposed method according to the invention is based on a temporary one-time secret S1EG (eg certificate) which, during configuration, ie during the establishment of the communication connection KV5, instead of the normally used secret (S1G; 1 , 2 , 4 ) is used, and is exchanged for the permanent secret S1G by the system S2 itself via the one-time endpoint EE-S1EG (e.g. port). Only the secret S1EG is exposed to the risk of loss. Its improper use can be noticed with certainty and its effect can be avoided. The one-time endpoint EE-S1EG can, for example, be set up as a network port by a service technician on the S2 system.

An attacker A, with access to the secret S1EG, can only use it up to the point at which it is used legitimately by the service technician, after which it is advantageously no longer valid. If an attacker A actually uses S1EG and has a secret S1G issued by the system S2, this becomes apparent at the latest when the service technician wants to use the one-time secret S1EG himself. The service technician will then have a new one-time secret issued, which in this case invalidates the permanent secret issued to the attacker and locks the attacker out again.

Advantageously, a one-time secret S1EG can only be used once. A one-time secret S1EG is a temporary secret (ie temporarily valid secret) that is only used to set up a secure communication link KV5 to the one-time endpoint EE-S1EG. With the one-time secret S1EG, the system S1 requests a permanent secret S1G from the system S2 ( 4 ) which is then used for operative communication, ie for setting up an operative communication connection between the systems S1 and S2.

A separate communication channel KV4, which is not detailed, is usually used to transmit the one-time secret S1EG, since the channel to be secured cannot be trusted before the relationship is established. For example, a service technician could transport the one-time secret S1EG (e.g. certificate) on a memory stick (e.g. USB stick, transport memory) TS, receive it by e-mail, but also download it to S1 via a (one-way) secure connection from S2. Since the one-time secret S1EG only has a provisional validity, it can in principle also be stored in a non-secure memory NS1 in the system S1. The one-time secret S1EG is advantageously stored in a secure memory SS1 (e.g. a memory with strong encryption) in the system S1. The one-time secret S1EG is transferred from system S2 to system S1 for the configuration/establishment of an operative communication connection.

4 shows another exemplary configuration for secure communication between two technical systems S1 and S2. The system S1 can be, for example, an IoT device (Internet of Things) that is to be connected in terms of data technology to the system S2 via the network NW (eg Internet, intranet, cloud, HTTPS network). The system S2 can be, for example, a regulating and control unit (controller) or a server. The server can be implemented (hosted) in a cloud infrastructure, for example. An IoT device can be, for example, an Internet-enabled field device (e.g. sensor, actuator) or an edge gateway. The network NW may be insecure.

The system S1 is in possession of the one-time secret S1EG issued by the system S2. The system S1 uses the one-time secret S1EG to identify itself to the one-time endpoint EE-S1EG of the system S2 via the temporary communication link KV6 and requests the secret S1G from the system S2. The secret S1G (e.g. certificate) is stored in the system S1 in a secure memory SS1 (non-corruptible memory) and is used for the operative communication link KV7 between the systems S1 and S2. If the operational communication link KV7 (via the secure endpoint SE-S1G) is set up, the temporary communication link KV6 advantageously becomes invalid.

The communication connection KV7 is used operationally (ie during operation) for the communication between the systems S1 and S2. Operational communication can include the transfer of data, commands, parameters, sensor values, etc.

During the configuration of the connection between the systems S1 and S2, the connection offers only limited rights regarding its use. After the secret S1G has been sent via the (temporary) communication link KV6, the one-time endpoint EE-S1EG is removed and is therefore invalid (worthless).

The procedure according to the invention uses a secret S1G published by system S2, which is kept in a secure memory SS1 of system S1 and with which system S1 identifies itself when connecting to system S2 at the intended endpoint (port, network port).

The procedure according to the invention offers a particularly convenient way of exchanging secrets and operating the communication link in such a way that the attack surface for a potential attacker remains minimal.

Example: An IOT gateway S1 is to be connected to a system S2 in the cloud NW. The cloud system S2 identifies itself, for example, with a TLS certificate signed by an authority trusted by the gateway. The gateway S1 can thus set up a secure connection to the cloud system S2, but the cloud system S2 does not know for certain that the communication partner is who he claims to be. To do this, the gateway S1 must identify itself, for example, with a combination of client-id and client-secret that is only known to it and the cloud system S2. The transfer of this secret can be carried out particularly conveniently and at the same time securely using the method described.

The procedure is particularly safe if the communication connection KV7 to be configured only has full functionality when the configuration has been successfully completed. Then even an attacker who has briefly obtained a permanent secret with the help of the one-time secret cannot cause any damage.

The procedure according to the invention is implemented by an arrangement for providing a secure communication link between two systems. The arrangement is advantageously implemented using means and components that are already available for setting up and operating technical systems that communicate via the Internet or via a cloud.

1. 1. Ein Servicetechniker legt in System S2 einen Einmal-Endpunkt EE-S1EG für System S1 an und konfiguriert ihn. Ein möglicherweise bestehender sicheren Endpunkt SE-S1G für ein vorher ausgestelltes Geheimnis S1G wird mit Vorteil ungültig.
2. 2. Der Servicetechniker lässt sich von System S2 das vorläufige Einmal-Geheimnis S1EG für System S1 ausstellen. Besonders vorteilhafte Merkmale für das Einmal-Geheimnis S1EG sind:
   1. a. Begrenzte Berechtigung - Einmal-Geheimnis S1EG berechtigt ausschließlich zum Ausstellen eines späteren dauerhaften Geheimnisses S1G.
   2. b. Einmalige Verwendung - nach der ersten Verwendung verliert es seine Gültigkeit.
   3. c. Exklusive Gültigkeit - die Ausstellung des Einmal-Geheimnisses S1EG invalidiert ein eventuell vorher ausgestelltes Geheimnis S1G für das System S1 und umgekehrt invalidiert das Geheimnis S1G ein vorher ausgestelltes Einmal-Geheimnis S1EG.
   4. d. Begrenzte Dauer - Einmal-Geheimnis S1EG gilt nur für eine definierte kurze Zeit, danach verfällt es.
   5. e. Begrenzter Scope - mit dem Einmal-Geheimnis S1EG kann nur das Geheimnis S1G für das bestimmte System S1 ausgestellt werden.
3. 3. Der Servicetechniker versorgt System S1 mit dem Einmal-Geheimnis S1EG. Einmal-Geheimnis S1EG muss im Gegensatz zum dauerhaften Geheimnis S1G auf dem Transportweg weniger sicher behandelt werden, da es praktisch kaum ausgenutzt werden kann.
4. 4. Das System S1 baut nun die Verbindung zu System S2 auf und weist sich mit dem Einmal-Geheimnis S1EG aus. Wie im Beispiel beschrieben kann diese Verbindung, die z.B. über das Internet (Netzwerk NW) verlaufen kann, z.B. über TLS abgesichert werden, so dass System S1 sicher sein kann, mit System S2 verbunden zu sein, und die Verbindung gegen Mitlesen abgesichert ist.
5. 5. System S1 lässt sich von System S2 nun das dauerhafte Geheimnis S1G ausstellen und schreibt es in seinen sicheren Speicher SS1. Auf diesem Wege ist es beim erfindungsgemäßen Verfahren vollständig geschützt.
6. 6. System S1 baut nun erneut die Verbindung zu System S2 auf und weist sich nun mit dem dauerhaften Geheimnis S1G aus. Die Konfiguration ist damit abgeschlossen und System S2 kann sicher mit System S1 kommunizieren.
7. 7. Der Servicetechniker kann nun die Verbindung auf System S2 mit den vollen Rechten ausstatten und somit aktivieren. Hätte ein Angreifer A sich zwischenzeitlich als System S1 ausgegeben, hätte er nur mit den bis dahin eingeschränkten Rechten keinen Schaden anrichten können.

The procedure according to the invention advantageously includes the following steps:

1. 1. A service technician creates and configures a one-time endpoint EE-S1EG for system S1 in system S2. A possibly existing secure endpoint SE-S1G for a previously issued secret S1G advantageously becomes invalid.
2. 2. The service technician has system S2 issue the provisional one-time secret S1EG for system S1. Particularly advantageous features for the one-time secret S1EG are:
   1. a. Limited authorization - one-time secret S1EG only entitles to issue a later permanent secret S1G.
   2. b. One-time use - after the first use it loses its validity.
   3. c. Exclusive validity—the issuance of the one-time secret S1EG invalidates any previously issued secret S1G for the system S1, and vice versa, the secret S1G invalidates a previously issued one-time secret S1EG.
   4. i.e. Limited duration - One-time secret S1EG is only valid for a defined short time, after which it expires.
   5. e. Limited scope - with the one-time secret S1EG, only the secret S1G can be issued for the specific system S1.
3. 3. The service technician supplies system S1 with the one-time secret S1EG. In contrast to the permanent secret S1G, one-time secret S1EG must be treated less securely on the transport route, since it can hardly be exploited in practice.
4. 4. The system S1 now establishes the connection to the system S2 and identifies itself with the one-time secret S1EG. As described in the example, this connection, which can run via the Internet (network NW), for example, can be secured via TLS, for example, so that system S1 can be sure that it is connected to system S2 and the connection is protected against eavesdropping.
5. 5. System S1 now has the permanent secret S1G issued to it by system S2 and writes it to its secure memory SS1. In this way it is completely protected in the method according to the invention.
6. 6. System S1 now establishes the connection to system S2 again and now identifies itself with the permanent secret S1G. The configuration is now complete and system S2 can safely communicate with system S1.
7. 7. The service technician can now provide the connection on system S2 with full rights and thus activate it. If an attacker A had posed as system S1 in the meantime, he would not have been able to cause any damage with only the previously restricted rights.

5 shows an exemplary flowchart for a method for providing a secure communication link between two technical systems.

• (VS1) Bereitstellen eines ersten Berechtigungsnachweises (z.B. Zertifikat, Credential) für ein erstes System (S1) von einem zweiten System (S2), wobei der erste Berechtigungsnachweis ein vorläufiges Einmalgeheimnis (SIEG) umfasst;
• (VS2) Bereitstellen eines Einmal-Endpunktes (EE-S1EG) im zweiten System (S2) für den Empfang des vom ersten System (S1) gesendeten vorläufigen Einmalgeheimnisses (SIEG);
• (VS3) Aufbauen einer ersten (vorläufigen) Kommunikationsverbindung vom ersten System (S1) zum Einmal-Endpunkt (EE-S1EG) im zweiten System (S2), basierend auf dem vorläufigen Einmalgeheimnis (SIEG);
• (VS4) Bereitstellen eines zweiten Berechtigungsnachweises (z.B. Zertifikat, Credential) für das erste System (S1) vom zweiten System (S2), wobei der zweite Berechtigungsnachweis ein dauerhaftes Geheimnis (S1G) umfasst, wobei das erste System (S1) das dauerhafte Geheimnis (S1G) in einen sicheren Speicher (SS1) des ersten Systems (S1) schreibt;
• (VS5) Aufbauen einer zweiten (operativen) Kommunikationsverbindung vom ersten System (S1) zum zweiten System (S2), basierend auf dem dauerhaften Geheimnis (S1G).

The procedure includes the following steps:

• (VS1) providing a first credential (eg certificate, credential) for a first system (S1) from a second system (S2), the first credential comprising a temporary one-time secret (SIEG);
• (VS2) providing a one-time endpoint (EE-S1EG) in the second system (S2) for receiving the temporary one-time secret (SIEG) sent from the first system (S1);
• (VS3) setting up a first (temporary) communication connection from the first system (S1) to the one-time endpoint (EE-S1EG) in the second system (S2), based on the temporary one-time secret (SIEG);
• (VS4) Providing a second credential (e.g. certificate, credential) for the first system (S1) from the second system (S2), the second credential comprising a persistent secret (S1G), the first system (S1) sharing the persistent secret ( S1G) writes to a secure memory (SS1) of the first system (S1);
• (VS5) Establishing a second (operative) communication link from the first system (S1) to the second system (S2) based on the permanent secret (S1G).

The system S1 can be, for example, an IoT device (Internet of Things), which is to be connected in terms of data technology to the system S2 via the network NW (e.g. Internet, intranet, cloud, HTTPS network). The system S2 can, for example, be a regulation and control unit (controller) or a server. The server can be implemented (hosted) in a cloud infrastructure, for example. An IoT device can be, for example, an Internet-enabled field device (e.g. sensor, actuator) or an edge gateway. The network NW may be insecure. Therefore, a secure communication connection KV1 (e.g. tunnel) should be created between the systems S1 and S2.

Advantageously, the temporary one-time secret (SIEG) can only be used to create the permanent secret (S1G).

Advantageously, the provisional one-time secret (SIEG) loses its validity after its first use.

Advantageously, the provisional one-time secret (SIEG) is valid for a defined period of time.

An advantageous embodiment is that after the provisional one-time secret (SIEG) has been issued, a previously issued permanent secret (S1G) loses its validity.

An advantageous embodiment is that after the permanent secret (S1G) has been issued, a previously issued provisional one-time secret (SIEG) loses its validity.

An advantageous embodiment is that with a temporary one-time secret (SIEG) issued for the first system (S1), a permanent secret (S1G) can only be issued for the first system (S1).

Advantageously, after the second (operative) communication connection has been set up, the temporary one-time secret (SIEG) loses its validity.

After the second (operative) communication connection has been set up, the one-time end point (EE-S1EG) is advantageously set (dismantled) in the second system (S2).

The method is advantageously implemented by means (hardware (suitable processor, memory and communication means) and software) and components that are already used for setting up and operating technical systems that communicate via the Internet or via a cloud, available.

Additional advantages

• - The procedure prevents attacks after the secure connection has been set up, since the vulnerable S1EG then no longer applies.
• - If successful, the S1G is not stored anywhere outside of the secured memory SS1.
• - The procedure limits the effects of successful attacks before the secure connection is set up, since system S2 only allows restricted rights for the connection until then.
• The method is suitable for automated configuration without further intervention by the service technician, who only has to initiate a download of the one-time secret S1EG on the system S1 to be configured.
• - Depending on the threat potential and the time span, the initial functional limitation of SE-S1G can optionally be dispensed with.
• - The method can also be used if there is no PKI encryption at the customer's site (on-premise).
• - The method can also be used if there are no machine certificates on site (on-premise) at the customer (especially when pre-assembled hardware is delivered).
• - The procedure secures, among other things, software (agents) that the customer installs on his physical machine (device) or on a VM (virtual machine).

A particularly convenient procedure for the method according to the invention results when the configuration of the complete connection can be triggered, for example, by a download from system S1, which the service technician only has to initiate from system S1, with system S1 using the downloaded configuration, the contains the one-time secret S1EG, can carry out the following steps independently and automatically. Only the activation with full rights should not take place automatically, this must be carried out by the service technician if necessary.

Method and arrangement for providing a secure communication connection between two systems, wherein a first credential for a first system is provided by a second system, wherein the first credential comprises a temporary one-time secret; wherein a one-time endpoint is provided in the second system for receiving the temporary one-time secret sent from the first system; wherein a first (temporary) communication link is established from the first system to the one-time endpoint in the second system based on the temporary one-time secret; wherein a second credential is provided to the first system by the second system, the second credential comprising a persistent secret, the first system writing the persistent secret to a secure storage of the first system; wherein a second (operative) communication link is established from the first system to the second system based on the persistent secret.

Reference List

S1, S2

system

A

attacker

SS1

Safe storage

NS1

Unsecured Storage

TS

transport storage

NW

network

S1G, S1EG

secret

SE-S1G

Secure Endpoint

EE-S1EG

one-time endpoint

KV1 - KV7

communication link

VS1 - VS5

process step

Claims (10)

Method for providing a secure communication link between two systems (S1, S2), comprising the following steps: (VS1) providing a first credential to a first system (S1) from a second system (S2), wherein the first credential comprises a temporary one-time secret (SIEG); (VS2) providing a one-time endpoint (EE-S1EG) in the second system (S2) for receiving the temporary one-time secret (SIEG) sent from the first system (S1); (VS3) setting up a first communication connection from the first system (S1) to the one-time endpoint (EE-S1EG) in the second system (S2), based on the temporary one-time secret (S1EG); (VS4) providing a second credential to the first system (S1) from the second system (S2), the second credential comprising a persistent secret (S1G), the first system (S1) storing the persistent secret (S1G) in a secure storage (SS1) of the first system (S1) writes; (VS5) establishing a second communication link from the first system (S1) to the second system (S2) based on the persistent secret (S1G). procedure after claim 1 , whereby the temporary one-time secret (SIEG) can only be used to create the permanent secret (S1G). procedure after claim 1 or 2 , whereby the provisional one-time secret (SIEG) loses its validity after its first use. Method according to one of the preceding claims, wherein the temporary one-time secret (SIEG) is valid for a defined period of time. Method according to one of the preceding claims, in which, after the temporary one-time secret (SIEG) has been issued, a previously issued permanent secret (S1G) loses its validity. Method according to one of the preceding claims, wherein a previously issued provisional one-time secret (SIEG) loses its validity after the permanent secret (S1G) has been issued. Method according to one of the preceding claims, wherein a temporary one-time secret (SIEG) issued for the first system (S1) can be used to issue a permanent secret (S1G) only for the first system (S1). Method according to one of the preceding claims, wherein the temporary one-time secret (SIEG) loses its validity after the second communication connection has been set up. Method according to one of the preceding claims, wherein the one-time endpoint (EE-S1EG) is set in the second system (S2) after the second communication connection has been set up. Arrangement for providing a secure communication link between two systems (S1, S2), comprising means for performing a method according to one of Claims 1 until 9 .

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