Method for encrypted transmission of data

Abstract

Methods for encrypted transmission of data are to be further developed so that the data is particularly well protected. The invention relates to a method for encrypted transmission (10) of data between terminals (14, 16), in which, before the transmission of the data, a verification certificate (Z * ) is created and transmitted to the backend (12), where it is signed by the root certificate (Z) and a signed verification certificate (Z ** ) is sent back to the second terminal device (16) along with the signed verification certificate (Z ** ) is transmitted to the first terminal device (14), verified using the public digital key (S2), and if verified, an encrypted one-time symmetric session key (S * ) is generated and this symmetric session key (S * ) is transmitted to the second terminal device (16) and a signed verification certificate (Z ** If the verification is unsuccessful, the information is notified to the first terminal device (14), while if the verification is successful, the data is decrypted using the private key of the session key (S * ) is used to decode the

Description

[Technical Field]

[0001] The present invention relates to a method for encrypted transmission of data according to the preamble of claim 1. [Background technology]

[0002] Confidential and personal data are increasingly being transmitted between two or more parties, including technical systems and subsystems of those systems, via IP-based communications, and must be protected from eavesdropping and manipulation by unauthorized third parties, including hacker attacks. Particularly in embedded systems, sensitive data must be protected from unauthorized access while it is stored and while it is being transmitted, for example via SOME / IP (Scalable Service-Oriented Middleware over IP), without placing a heavy load on the CPU.

[0003] For example, vulnerability to easy access to private keys for encrypting and decrypting data can jeopardize the security of the entire system. When information is exchanged over a public network, it passes through multiple intermediary nodes, some of which may be of questionable trustworthiness. Therefore, data must be fully encrypted before or during transmission from the sender and decrypted after receipt by the receiver. The parties or endpoints must constantly protect and temporarily exchange keys capable of cryptographically decrypting each other's messages. Furthermore, the keys must be protected from unauthorized access if the encrypted data is intercepted by an unauthorized third party through other security holes, such as in the cloud.

[0004] From the patent document JP 2003-102499 A, a method and a chip for cryptographically encrypting data are already known. This method realizes encryption and decryption of data according to the stream principle using a symmetric cipher algorithm. This prior art example also relies on a novel cryptographic method, which is implemented in a novel chip. The so-called BAPA chip for implementing this method in hardware is a novel cryptographic chip that supports the entire range of electronic data communications. However, hardware-dependent encryption and processing by this chip or other chips has the disadvantage that it cannot be integrated into any embedded system, especially if the existing embedded system does not allow modifications to the hardware and its architecture.

[0005] Similarly, Patent Document 2 listed below already discloses end-to-end encryption for personal communication nodes, which corresponds to end-to-end encryption of group communications for personal communication nodes. This is provided by implementing a pairwise encryption process between end-user devices that are members of a communication group. Here, each end-user device shares a group key with its paired end-user device. The group key is also encrypted using a message key created using the pairwise encryption method. When a transmitting member in a group communicates with another member, the transmitting member creates a stream key, encrypts the stream data with the stream key, encrypts the stream key with the group key, and transmits the encrypted stream key and encrypted stream data to the group member. A drawback of this method is, among other things, that communication groups must be registered in advance with a server along with their identification keys and public keys. For encrypted communications, a secure connection must be actively established in advance between the paired end-user devices. The message key is not encrypted and therefore may be intercepted by unauthorized third parties, including hackers.

[0006] Furthermore, the following patent document 3 discloses a secure logical communication connection between a secure payment module and a controller for secure communication in a one-to-one transaction environment, where the communication connection is established by cryptographic authentication by a device that processes sensitive information in the one-to-one transaction environment. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent No. 10 355 865 B4 [Patent Document 2] US Patent Application Publication No. 2018 / 063094 A1 [Patent Document 3] Canadian Patent Application Publication No. 2 703 612 A1 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the invention is to further develop a method for encrypted transmission of data in such a way that the data is particularly well protected. [Means for solving the problem]

[0009] This problem is solved according to the invention by a method with the features of claim 1. Advantageous embodiments, including preferred developments of the invention, are the subject of the dependent claims.

[0010] One aspect of the present invention relates to a method for encrypted data transmission over a network between a first terminal device transmitting the data and at least one second terminal device receiving the data, wherein the network and the terminal devices include all components necessary for data transmission, thereby realizing communication between the terminal devices and a backend of the network. The method includes a first method step of generating a first private digital key, a second public digital key, and a root certificate, wherein the two keys are generated to correspond to each other and are certified by the root certificate. The root certificate, or origin certificate, is a certificate signed by the certification authority itself. The root certificate is used to verify the validity of all certificates (in this case, keys) issued by the certification authority. In particular, the generation is performed in the backend of the network. Further method steps include firstly performing protected storage of the private first digital key in the backend of the network, and generating and storing, for each terminal device, a respective key copy of the public second digital key. Subsequently, two identical public second digital keys are directly generated and transmitted or transferred to the respective terminal devices, or the identical public second digital keys are already pre-installed in the respective terminal devices, in which case only one key can be generated first, and then copies of that key are generated.

[0011] To achieve the object of the present invention, and thus to further develop a method for encrypted data transmission so that data is particularly securely protected, the present invention provides a method in which, before data transmission between a first terminal device as a sender and a second terminal device as a receiver, a verification certificate is generated by the second terminal device, i.e., the receiver terminal device, and transmitted to a backend where it is signed with a root certificate. The signed verification certificate is then returned to the second terminal device, and the public second digital key of the signed verification certificate is transmitted to the first or sender terminal device, where it is verified using a unique key copy of the public second digital key. If the verification is unsuccessful, the encrypted data transmission from the first or sender terminal device is not permitted. If the verification is successful, a one-time symmetric session key is generated, encrypted using a key copy of the public second digital key of the signed verification certificate, and the data to be transmitted is encrypted using this session key. The encrypted session key and the data encrypted using the session key are then transmitted to a second, i.e., receiving, terminal device, where they are decrypted using the unique, private first digital key of the verification certificate; if verification is unsuccessful, the first, i.e., sending, terminal device is notified; if verification is successful, the data is decrypted using the session key. Thus, using the session key and the verification certificate, highly secure transmission of data is provided against unauthorized third parties, including hackers.

[0012] In other words, embodiments of a method are provided for hybrid end-to-end (E2E) encryption, authentication and authorization of sensitive communications between two or more parties, including technical systems, particularly for embedded systems.

[0013] In this embodiment, a root certificate is first generated with a private key and a public key for a system consisting of a terminal device and a network including a backend, on which the method is intended to be implemented. The secret first digital key is stored and protected in a common backend. The public key is initially stored in each terminal device or, for example, pre-installed in an ECU that does not include a backend connection. A "push" occurs when one terminal device wants to send sensitive data to another terminal device, or a "pull" occurs when the other terminal device requests a one-time verification certificate containing the public key signed by the root certificate from the receiving terminal device via the backend. A "push" then receives it from the receiving terminal device. The sending terminal then verifies the signature and validity period of the verification certificate using the public key of the root certificate. If there is a match, further steps of the method are initiated; otherwise, transmission to the receiving terminal is rejected. Furthermore, a one-time symmetric session key is generated, and this session key is used to encrypt the confidential data to be transmitted, where the session key is encrypted using the public key of the verification certificate. The encrypted confidential data and the encrypted session key are then transmitted to the receiving terminal. Finally, the receiving terminal decrypts the session key using the private first digital key of the verification certificate. If the signature and validity period match, further method steps are initiated, and the confidential data is decrypted using the session key. If there is no match, a signal is used to inform the sending terminal.

[0014] In a preferred embodiment of the invention, the generation of the private first digital key, the public second digital key and the root certificate is triggered by a command transmitted from one of the terminals to the backend. This means that the terminals are configured in such a way that this command can be transmitted at any time via an input, so that the data transmission can be initiated by the user of the terminal. Alternatively, it is also possible to realize the triggering of the generation by a command from another node point of the server, for example by a partially autonomous or autonomous terminal.

[0015]

[0013] An embodiment of the present invention is further advantageous in which the published second digital key is protected in a separate memory outside the network. For example, the published second digital key generated thereby and transmitted to each terminal device can be transmitted to a memory connected to the terminal device, thereby preventing the key from being lost in the event of a terminal device failure. In particular, storing the key in a memory outside the network provides key security and avoids the generation of new keys, thereby at least partially reducing the working memory usage in this method, for example.

[0016] In a further advantageous embodiment of the invention, the secret first digital key is stored in a protected memory external to the network. This external storage ensures that the data stored in the backend remains protected in a separate memory. This is particularly advantageous when using a third-party network provider, since the external memory can be installed, for example, by the OEM, and thus a key backup is provided and can only be provided by the OEM.

[0017] In a further advantageous embodiment of the present invention, the public second digital key is initially stored in each terminal device. This not only avoids key generation, but also allows a unique key to be assigned to only this one terminal device, thereby providing simplified but nevertheless more secure encryption, for example, by an already implemented cryptographic process without the need to prepare a working memory for a new key. The public second digital key is initially stored in each terminal device or is pre-installed, for example, in an ECU that does not include a back-end connection. The root certificate can be issued (used) for a relatively long period, for example, more than 20 years, and can be updated as needed.

[0018] Likewise advantageous is an embodiment of the invention in which consecutive unsuccessful checks are counted by a counter. In this case, the counter should be triggered whenever a check is unsuccessful for various reasons. In this case, it is possible to classify these reasons and store data on the failures for statistical evaluation and improvement. Similarly, various counters can be incorporated into the method in order to collect various data and information.

[0019] Another embodiment of the invention is also advantageous, in which at least one warning signal is triggered if the count in the counter exceeds a predetermined value. In particular, login attempts by third parties, as well as hacking attacks, should be immediately identified and forwarded to the network. This allows possible unauthorized intervention to be immediately blocked, so that no transmission takes place.

[0020] In a further advantageous embodiment of the present invention, a validity period of the verification certificate or the signed verification certificate is set, so that the encrypted transmission is limited in time. When a back-end connection with the back-end is established and communication takes place over a public network, the validity period of the verification certificate is significantly reduced to one day or even two hours, depending on the application, in order to prevent unauthorized interception of data by hackers, for example. This time limit in the method also provides a period for the transmission of data that is interrupted after a set time has elapsed. This prevents unauthorized intervention in the transmission.

[0021] The following are particularly advantageous: - Via the root certificate and the verification certificate, the sending terminal device is guaranteed (authenticated and authorized) to transmit sensitive data only if the root certificate successfully verifies the validity period and signature of the verification certificate, i.e., if the validity period and signature of the verification certificate originate from an authorized terminal device. - Via the verification certificate generated for the current communication session, it is ensured (authenticated) that sensitive data is encrypted and decrypted using a session key protected by the verification certificate. A symmetric session key encrypted or decrypted by an asymmetric confirmation key can encrypt or decrypt sensitive data without placing a heavy load on the CPU of an embedded system. If an end device or component, e.g. an ECU in an embedded system that does not include a back-end connection, needs to transmit sensitive data in a protected manner to another end device or component, this can be done without a back-end connection, however the previous verification certificate that is still valid must be used, which is achieved in a protected embedded system with a longer validity period. -When a back-end connection is established and communication takes place over a public network, the validity period of the verification certificate is significantly reduced to one day or even two hours, depending on the application, to avoid fraudulent replies by hackers. Additional terminal devices or components can be more easily added to a system protected by their unique authentication certificate using a common root certificate.

[0022] Further advantages, features and details of the present invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned in the above description and in the following description of the figures and / or shown only in the figures can be used not only in the respective combinations presented, but also in other combinations or alone without departing from the scope of the present invention. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a diagram for explaining an embodiment of the method according to the invention for encrypted transmission 10 of data, in particular using hybrid E2E encryption and authentication; DETAILED DESCRIPTION OF THE INVENTION

[0024] In this example, a network is shown that includes a backend 12, a first terminal device 14, and a second terminal device 16. The backend 12 has access to registered terminal devices, namely the first terminal device 14 and the second terminal device 16. In this example, the first terminal device 14 is represented as the sender and the second terminal device 16 is represented as the receiver.

[0025] 1 shows a loop including a query (request) for the method, starting with initialization 20 to create or generate a root certificate Z, not shown, and a first private digital key S1, not shown, and a second public digital key S2, not shown. The public second digital key S2 is copied to create or generate a first key copy K1 and a second key copy K2, thereby transferring the key copies to all terminal devices 14, 16 and encrypting and protecting authorized transmissions of sensitive data. Thus, in initialization 22, a common root certificate Z is created and a protected private first digital key S1 is created. This is followed by transmission 24 of key copy K1 to the first terminal device 14 and transmission 26 of key copy K2 to the second terminal device 16.

[0026] This is followed by a sequence 28 including alternating inquiries between the first terminal device 14 and the second terminal device 16, which triggers an inquiry 30 (Pull) by the second terminal device 16 to send sensitive data. This is followed by the first terminal device 14 sending the sensitive data (Push) by the second terminal device 16, which then sends the publicly available second digital key S2 or the verification certificate Z * A request 32 for a key copy K1 for . A valid verification certificate Z in case the back-end connection is unavailable * Reuse 33 of the is required, for example, for embedded components that do not include a back-end connection, in which case initialization is performed.

[0027] Then, the second terminal device 16 receives the verification certificate Z * Then, the original certificate, i.e., the root certificate Z, is used to generate the verification certificate Z. * A query 36 is made to the backend 12 to sign the verification certificate Z. The backend 12 then sends the signed verification certificate Z to the second terminal device 16. **A return 38 of the signed public second digital key S2 for the sensitive data is then made. A transmission 40 then takes place, in which the second terminal device 16 returns the signed public second digital key S2 or the signed verification certificate Z ** The key copy K1 is returned to the first terminal device 14.

[0028] The subsequent steps of the first terminal device 14 are as follows: In a first step 42, the signature and the signed verification certificate Z ** The validity of the certificate is verified using the publicly available second digital key S2 or the key copy K1 of the root certificate Z. If verification fails, a stop 46 is performed, which stops the process and notifies the second terminal device 16, which is the receiving side. In a second step 44, a random session key, i.e. a one-time symmetric session key S * is generated. In a third step 48, all sensitive data is encrypted using the session key S * is encrypted by In a fourth step 50, the session key S * is a publicly available second digital key S2 or a signed verification certificate Z ** is encrypted using the key copy K1. Finally, in a fifth step, the first terminal device 14 sends the encrypted data and the session key S * to the second terminal 16 and a corresponding decryption 54. The second terminal 16 then receives the authentication certificate Z * Session key S is generated using the secret first digital key S1. * If this does not work, a Stop 58 is performed to stop the process and inform the sender, the first terminal device 14. Otherwise, a Decryption 56 is performed, in which the second terminal device 16 uses the session key S * This completes the method for encrypted transmission of data.

[0029] In other words, in FIG. 1 a method for encrypted transmission 10 of data between terminal devices 14, 16 over a network is shown, which method comprises the following method steps: generating a private first digital key S1 and a public second digital key S2, and a root certificate Z; - storing the secret first digital key S1 securely in the network backend 12; generating and storing in each terminal device 14, 16 a respective key copy K1, K2 of the public second digital key S2; In this case, before transmitting the data, the second terminal device 16 (receiving terminal device) is used to obtain the confirmation certificate Z * is created and transmitted to the backend 12, where it is signed by the root certificate Z. Subsequently, the signed verification certificate Z ** is transmitted to the first terminal device 14 and verified by the first terminal device 14 (the sending terminal device) using a unique key copy K1 of the publicly disclosed second digital key S2. If verification is unsuccessful, the encrypted transmission of the data is not permitted, and if verification is successful, a signed verification certificate Z ** a one-time symmetric session key S encrypted using a key copy K1 of the public second digital key of * Furthermore, a session key S * is transmitted to the second terminal device 16, and the signed verification certificate Z ** The data is decrypted using the unique secret first digital key S1, and if the verification (decryption) is unsuccessful, the information is notified to the first terminal device 14, or if the verification is successful, the data is decrypted using the session key S2. * is decrypted using

[0030] Furthermore, the generation of the private first digital key S1 and the public second digital key S2, as well as the root certificate Z, can be initiated by instructions transmitted from one of the terminal devices 14, 16 to the backend 12. Similarly, the public second digital key S2 can be encrypted and stored in a memory external to the network. Furthermore, the private first digital key S1 can be encrypted and stored in a memory external to the network. Also, the public second digital key K1 or K2 can be initially stored in the terminal device 14, 16, respectively.

[0031] Consecutive unsuccessful verifications may be counted by a counter, and at least one warning signal may be triggered if the count in the counter exceeds a predetermined value.

[0032] Similarly, confirmation certificate Z * , or signed confirmation certificate Z ** A validity period may be set, limiting the encrypted transmission to a certain time. [Explanation of symbols]

[0033] 10 Encrypted Transmission 12 Backend 14 First terminal device 16 Second terminal device 20 Initialization 22 Initialization 24 Send 26 Send 28 Sequence 30 Inquiries 32 requests 33 Reuse 34 generation 36 Inquiries 38 retransmission 40 Transmission 42 First Step 44 Second Step 46 Stop 48 Third Step 50 Fourth Step 52 Transmission 54 Decryption 56 Decryption 58 Stop K1 First key copy K2 Second key copy S1 First Key S2 Second Key S * Session Key

Claims

1. A method for encrypted transmission (10) of data over a network between a first terminal device (14) transmitting the data and at least one second terminal device (16) receiving the data, comprising: - generating a private first digital key (S1) and a public second digital key (S2), and a root certificate (Z); - storing said secret first digital key (S1) securely in a backend (12) of said network; generating and storing respective key copies (K1, K2) of the public second digital key (S2) for each of the terminal devices (14, 16) and transmitting the respective key copies (K1, K2) to the respective terminal devices (14, 16); 1. A method comprising: - before transmitting said data, said second terminal device (16) sends a confirmation certificate (Z ＊ ) is created and transmitted to the backend (12), where it is signed by the root certificate (Z), - Signed verification certificate (Z ＊＊ ) is returned to the second terminal device (16), and the signed verification certificate (Z ＊＊ ) is transmitted to the first terminal device (14) and verified using the unique key copy (K1) of the public second digital key (S2), and if verification is unsuccessful, the encrypted transmission of data by the first terminal device (14) is not permitted, while if verification is successful, the signed verification certificate (Z ＊＊ a one-time symmetric session key (S) encrypted with the key copy (K1) of the public second digital key (S2) of ＊ ) is generated, and the session key (S ＊ ) to encrypt the data to be transmitted, - the encrypted session key (S ＊ ) and the encrypted session key (S ＊ ) and the data encrypted by the signed verification certificate (Z) are transmitted to the second terminal device (16), ＊＊ ) is decrypted using the unique secret first digital key (S1), and if the verification is unsuccessful, the information is notified to the first terminal device (14), while if the verification is successful, the data is decrypted using the session key (S ＊ ) is decoded using A method characterized by:

2. The generation of the private first digital key (S1) and the public second digital key (S2), and the root certificate (Z), is initiated by a command transmitted from one of the terminal devices (14, 16) to the backend (12).

2. The method according to claim 1, characterized in that

3. The publicly disclosed second digital key (S2) is encrypted and stored in a memory external to the network.

3. The method according to claim 1 or 2, characterized in that

4. The secret first digital key (S1) is stored encrypted in a memory external to the network.

4. The method according to claim 1, wherein the

5. The publicly disclosed second digital key (K2) is initially stored in each of the terminal devices (14, 16).

5. The method according to claim 1, wherein the

6. A counter counts consecutive unsuccessful checks 6. The method according to any one of claims 1 to 5, characterized in that

7. If the count in the counter exceeds a predetermined value, at least one warning signal is triggered.

7. The method according to claim 6, characterized in that

8. The confirmation certificate (Z ＊ ) validity period is set 8. The method according to any one of claims 1 to 7, characterized in that

9. The signed confirmation certificate (Z ＊＊ ) validity period is set 9. The method according to any one of claims 1 to 8, characterized in that

10. The encrypted transmission is time-limited 10. The method according to any one of claims 1 to 9, characterized in that

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