Methods for encrypted data transmission

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 data transmission as described in the first part of claim 1. [Background technology]

[0002] The transmission of confidential and personal data between two or more parties, including technical systems and their subsystems, via IP-based communications is becoming increasingly common, and in such cases, this confidential and personal data needs to be protected from eavesdropping and unauthorized manipulation by unauthorized third parties, including hacker attacks. In particular, in embedded systems, highly confidential 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, a vulnerability that allows easy access to private keys for data encryption and decryption could jeopardize the security of the entire system. When information is exchanged over a public network, it passes through multiple relay nodes, and the reliability of these relay nodes may be questionable. Therefore, data must be fully encrypted before or during transmission from the sender and decrypted after reception by the receiver. In this process, the parties or endpoints must always protect and temporarily exchange the keys that can cryptographically decrypt each other's messages. Furthermore, the keys must also be protected from unauthorized access if encrypted data is intercepted through other security holes, for example, by an unauthorized third party in the cloud.

[0004] A method and chip for cryptographically encrypting data are already known from Patent Document 1 below. This method achieves data encryption and decryption using a symmetric cipher algorithm according to the stream principle. Similarly, this example of prior art is based on a novel cryptographic method realized / implemented by 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 have the disadvantage that they cannot be integrated into any embedded system, especially when existing embedded systems do not allow changes to the hardware and its architecture.

[0005] Similarly, Patent Document 2 below already discloses end-to-end encryption for personal communication nodes, which is end-to-end encryption for group communications for personal communication nodes. This is provided by implementing an encryption process performed by pairs of end-user devices that are members of a communication group. Here, the end-user devices share a group key with the paired end-user devices. The group key is also encrypted using a message key created using the encryption method performed by the pair. When a transmitting member in the group communicates with other members, 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 members. A drawback of this method is that, in particular, the communication groups must be registered with the server in advance along with their identification key and public key. For encrypted communication, a secure connection must be actively established in advance between pairs of end-user devices. Since the message key is not encrypted, it can therefore be intercepted by unauthorized third parties, including hackers.

[0006] Furthermore, 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, and this communication connection is established by cryptographic authentication by a device that processes sensitive information in a one-to-one transaction environment. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] German Patent No. 10 355 865 B4 Specification [Patent Document 2] U.S. Patent Application Publication 2018 / 063094, Specification A1 [Patent Document 3] Canadian Patent Application Publication No. 2 703 612 A1 Specification [Overview of the project] [Problems that the invention aims to solve]

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

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

[0010] One aspect of the present invention relates to a method for encrypted transmission of data over a network between a first terminal device transmitting data and at least one second terminal device receiving data. Here, the network and terminal devices include all components necessary for data transmission, thereby enabling communication between the terminal devices and the network backend. The method comprises several method steps, in which the generation of a first secret digital key, a published second digital key, and a root certificate is carried out. Here, the two keys are generated to correspond to each other and are certified by the root certificate. The root certificate, or original certificate, is a certificate signed by the Certificate Authority itself. The root certificate is used to verify the validity of all certificates (in this case, keys) issued by the Certificate Authority. In particular, the generation is carried out at the network backend. In further method steps, the protected storage of the secret first digital key is first carried out at the network backend, and the generation and storage of each key copy of the published second digital key for each terminal device is carried out. Subsequently, two identical, publicly available second digital keys are directly generated and transmitted or transferred to each terminal device, or these identical, publicly available second digital keys are already pre-installed on each terminal device. In this case, only one key can be generated first, followed by the generation of copies of that key.

[0011] To solve the problems of the present invention, and therefore to further develop a method for encrypted data transmission such that the data is particularly strongly protected, the present invention provides a verification certificate (Verifikationszertifikat) created by the second terminal device, i.e., the receiving terminal device, before data is transmitted between a first terminal device as the sender and a second terminal device as the receiver, and transmitted to the backend, where it is signed by a root certificate. Subsequently, the signed verification certificate is sent back to the second terminal device, and the published second digital key of the signed verification certificate is transmitted to the first terminal device or the sending terminal device, where it is verified (matched) using a unique key copy of the published second digital key. If the verification is unsuccessful, encrypted data transmission from the first terminal device or the sending terminal device is not permitted. On the other hand, if the verification is successful, a one-time symmetric session key is generated, encrypted using a key copy of the published second digital key of the signed verification certificate, and the data to be transmitted is encrypted using this session key. Next, the encrypted session key and the data encrypted using that session key are transmitted to a second terminal device, i.e., the receiving terminal device, where they are decrypted using the unique secret first digital key of the verification certificate. If the verification is unsuccessful, the information is sent to the first terminal device, i.e., the sending terminal device. On the other hand, if the verification is successful, the data is decrypted using the session key. Thus, the session key and verification certificate provide a highly secure transmission of data to unauthorized third parties, including hackers.

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

[0013] In this embodiment, first, a root certificate is generated along with a private key and a public key for a system consisting of terminal devices and a network including a backend, which is intended to implement this method. The private first digital key is stored and protected in a common backend. The public key is initially stored in each terminal device or pre-installed in an ECU that does not include a backend connection, for example. When one terminal device intends to send highly sensitive data to the other terminal device, it is called a "push," or when requested by the other terminal device, it is called a "pull." In the case of a "push," the receiving terminal device requests a one-time verification certificate containing the public key, signed by the root certificate via the backend; in the case of a "pull," it receives them from the receiving terminal device. Furthermore, the sending terminal device verifies the signature and validity period of the verification certificate using the public key of the root certificate. If they match, and therefore verification is obtained, the further steps of this method are initiated; otherwise, transmission to the receiving terminal device is refused. Furthermore, a one-time symmetric session key is generated, and this session key is used to encrypt the sensitive data to be transmitted, using the publicly available key of the verification certificate. Subsequently, the encrypted sensitive data and the encrypted session key are transmitted to the receiving terminal device. Finally, the receiving terminal device decrypts the session key using the secret first digital key of the verification certificate. If the signature and validity period match, a further method step is initiated, and the sensitive data is decrypted using the session key. If they do not match, the information is notified to the sending terminal device using a signal.

[0014] In an advantageous embodiment of the present invention, the generation of a secret first digital key, a public second digital key, and a root certificate is triggered by an instruction transmitted from one of the terminal devices to the backend. This means that the terminal device is configured such that this instruction can be transmitted at any time via an input, thereby enabling the user of the terminal device to initiate data transmission. Alternatively, it is similarly possible to realize a trigger for generation by an instruction from another node point of the server, for example, by a semi-autonomous or autonomous terminal device.

[0015] An embodiment of the present invention in which the public second digital key is protected in another memory outside the network is even more advantageous. For example, the public second digital key generated thereby and transmitted to each terminal device can be transmitted to the memory connected to the terminal device, thereby preventing the key from being lost in case of a failure of the terminal device. In particular, the preservation of the key is realized by storing the key in a memory outside the network, and the generation of a new key is avoided, whereby, for example, the use of the working memory is at least partially reduced in this method.

[0016] In a further advantageous embodiment of the present invention, the secret first digital key is protected and stored in a memory outside the network. In this case, the external storage enables the data stored in the backend to be maintained in a protected state in another memory. This is particularly advantageous when using a third-party network provider. Because the memory outside the network can be installed, for example, by an OEM, and thus a backup of the key is realized and can only be provided by the OEM.

[0017] In a further advantageous embodiment of the present invention, the published second digital key is first stored in each of the terminal devices. By doing so, not only is key generation avoided, but since only one unique key is assigned to this one terminal device, for example, without the need to prepare a working memory for a new key, a simplified but still more secure encryption is provided by the already implemented encryption process. The published second digital key is first stored in each of the terminal devices or pre-installed, for example, in an ECU without a back-end connection. The root certificate can be issued (used) for a relatively long period, for example, exceeding 20 years, and can be updated as needed.

[0018] Embodiments of the present invention in which the confirmations that have continuously ended unsuccessfully are counted by a counter are similarly advantageous. In this case, when the confirmation ends unsuccessfully for various reasons, the counter should always be triggered. In this case, it is possible to classify those reasons and store the data regarding the failures for statistical evaluation and improvement. Similarly, various counters can be incorporated into the method to collect various data and information.

[0019] Another embodiment of the present invention in which at least one warning signal is triggered when the count in the counter exceeds a predetermined value is similarly advantageous. In particular, attempts to log in by a third party and hacking attacks should be immediately identified and transferred to the network. By doing so, possible unauthorized interventions can be immediately blocked, and as a result, the transmission is not performed.

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

[0021] The following points are particularly advantageous: - Through the root certificate and verification certificate, if the root certificate successfully verifies the validity period and signature of the verification certificate, that is, only if the validity period and signature of the verification certificate originate from an authorized terminal device, is it guaranteed (authenticated and authorized) that the sending terminal device can transmit highly confidential data. - Through a verification certificate generated for the current communication session, it is guaranteed (authenticated) that highly sensitive data will be encrypted and decrypted using the session key protected by the verification certificate. - Symmetric session keys, which are encrypted or decrypted by asymmetric verification keys, can encrypt or decrypt highly sensitive data without placing a heavy load on the embedded system's CPU. -Even if an ECU in an embedded system that does not include a backend connection needs to transmit highly sensitive data to another terminal device or component in a protected manner, this can be done without using a backend connection; however, the previously valid verification certificate must still be used, and this is achieved with a longer validity period in a protected embedded system. -When a backend connection is established and communication takes place over a public network, the validity period of the verification certificate is drastically reduced to one day, or even as short as two hours, depending on the application, in order to prevent malicious replies (Replays) by hackers. - Another terminal device or component can be more easily added to a protected system using their own verification certificates with 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 the features and combinations of features mentioned in the following description relating to each figure, and / or the features and combinations of features shown only in each figure, are not limited to the combinations presented, but can also be used in other combinations or individually without departing from the scope of the present invention. [Brief explanation of the drawing]

[0023] [Figure 1] This figure illustrates an embodiment of the method according to the present invention for encrypted data transmission 10, particularly using hybrid end-to-end encryption and authentication. [Modes for carrying out the invention]

[0024] This example shows a network including a backend 12, a first terminal device 14, and a second terminal device 16. The backend 12 can access the 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] Figure 1 shows a loop that includes queries (requests) about this method, starting with initialization 20 to create or generate a root certificate Z (not shown), a secret first digital key S1 (not shown), and a publicly disclosed second digital key S2 (not shown). The publicly disclosed second digital key S2 is copied so that a first key copy K1 and a second key copy K2 are created or generated, thereby transferring the key copies to all terminal devices 14, 16, and encrypting and protecting authorized transmissions of highly confidential data. Thus, initialization 22 creates a common root certificate Z and a protected secret first digital key S1. Subsequently, key copy K1 is sent to the first terminal device 14 24, and key copy K2 is sent to the second terminal device 16 26.

[0026] Following this, a sequence 28 is performed, which includes alternating queries between the first terminal device 14 and the second terminal device 16. In this sequence 28, a query 30 (Pull) is triggered by the second terminal device 16 to send highly confidential data. Subsequently, the first terminal device 14 sends (Push) the highly confidential data, which is then publicly disclosed. The second digital key S2 or the verification certificate Z * A request for a key copy K1 is made for 32. A valid verification certificate Z is requested in case the backend connection is unavailable. * Reuse 33 is required, for example, in embedded components that do not include backend connections, in which case initialization is performed.

[0027] Subsequently, the second terminal device 16 receives the confirmation certificate Z * The generation 34 is performed, followed by the use of the original certificate, i.e., the root certificate Z, to verify the certificate Z. * A query 36 is made to the backend 12 in order to sign it. Then, the signed confirmation certificate Z is sent from the backend 12 to the second terminal device 16. **A return 38 is performed. Subsequently, a transmission 40 is performed. Here, the second terminal device 16 returns a signed and published second digital key S2 or a signed confirmation certificate Z for highly confidential data, ** or a key copy K1 of

[0028] to the first terminal device 14. - In the first step 42, the validity of the signature and the signed confirmation certificate Z ** is verified using the published second digital key S2 or the key copy K1 of the root certificate Z. If the verification fails, a stop (Stopp) 46 is performed, stopping the process and notifying the receiving second terminal device 16 of the information. - In the second step 44, a random session key, i.e., a one-time symmetric session key S * is generated. - In the third step 48, all highly confidential data is encrypted by the session key S * . - In the fourth step 50, the session key S * is encrypted using the published second digital key S2 or the key copy K1 of the signed confirmation certificate Z ** . Finally, in the fifth step, the first terminal device 14 performs a transmission 52 of the encrypted data and the session key S * to the second terminal device 16, and a corresponding decryption 54 is performed. Here, the second terminal device 16 decrypts the session key S * using the secret first digital key S1 of the confirmation certificate Z * . If this fails, a stop (Stopp) 58 is performed, stopping the process and notifying the transmitting first terminal device 14 of the information. Otherwise, a decryption 56 is performed, in which the second terminal device 16 decrypts the highly confidential data using the session key S * . This concludes the method for encrypted transmission of data.

[0029] In other words, Figure 1 shows a method for encrypted data transmission 10 between terminal devices 14 and 16 over a network, which includes the following method steps: - A step of generating a secret first digital key S1, a published second digital key S2, and a root certificate Z; - A step to store the secret first digital key S1 so that it is protected on the network backend 12; - A step of generating key copies K1 and K2 of the publicly released second digital key S2 and storing them in the respective terminal devices 14 and 16; In this case, before data transmission, the second terminal device 16 (receiving terminal device) is used to obtain the verification certificate Z * The verification certificate Z is created and transmitted to backend 12, where it is signed by root certificate Z. Subsequently, the signed verification certificate Z ** However, the data is transmitted to the first terminal device 14 and verified by the first terminal device 14 (the transmitting terminal device) using the unique key copy K1 of the publicly disclosed second digital key S2. If the verification is unsuccessful, the encrypted transmission of the data is not permitted. If verification is successful, a signed verification certificate Z is issued. ** A one-time symmetric session key S, encrypted using the key copy K1 of the publicly released second digital key. * A session key S is generated. * The data is transmitted to the second terminal device 16, and the signed verification certificate Z is transmitted. ** The data is decrypted using the unique secret first digital key S1. If the verification (decryption) fails, the information is notified to the first terminal device 14, or if verification is successful, the data is decrypted using the session key S * It is decrypted using [this method].

[0030] Furthermore, the generation of the secret first digital key S1, the published second digital key S2, and the root certificate Z can also be initiated by an instruction transmitted from one of the terminal devices 14 or 16 to the backend 12. Similarly, the published second digital key S2 can be encrypted and stored in memory outside the network. Furthermore, the secret first digital key S1 can be encrypted and stored in memory outside the network. In addition, the published second digital key K1 or K2 can initially be stored in terminal devices 14 or 16, respectively.

[0031] If the verification process fails repeatedly, this can be counted by a counter, and if the count in the counter exceeds a predetermined value, at least one warning signal can be triggered.

[0032] Similarly, verification certificate Z * , or a signed verification certificate Z ** It is also possible that an expiration period may be set, limiting encrypted transmission to a specific time frame. [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 Sequences 30 Inquiries 32 requests 33 Reuse 34 generation 36. Inquiry 38 Resend 40 Transmission 42. Step 1 44. Second Step 46 Stop 48. The Third Step 50. Step 4 52 Transmission 54 Decryption 56 decrypt 58 Stop K1 First Key Copy K2 Second Key Copy S1 The First Key S2 The Second Key S * Session key

Claims

1. A method for encrypted data transmission (10) over a network between a first terminal device (14) that transmits data and at least one second terminal device (16) that receives data, - The backend (12) of the network generates a secret first digital key (S1), a publicly available second digital key (S2), and a root certificate (Z), - The backend stores the secret first digital key (S1) in a manner that protects it, The steps include generating and storing key copies (K1, K2) of the publicly available second digital key (S2) for each of the aforementioned terminal devices (14, 16), and transmitting the respective key copies (K1, K2) to each of the aforementioned terminal devices (14, 16), In a method having, - Before the transmission of the aforementioned data, the second terminal device (16) will issue 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 confirmation certificate (Z ＊＊ The publicly disclosed second digital key (S2) of the first terminal device (14) is transmitted to the first terminal device (14) and verified using the unique key copy (K1) of the publicly disclosed second digital key (S2). If the verification is unsuccessful, the encrypted transmission of data by the first terminal device (14) is not permitted. On the other hand, if verification is successful, the signed verification certificate (Z ＊＊ A one-time symmetric session key (S) encrypted using the key copy (K1) of the publicly disclosed second digital key (S2) of (S2). ＊ ) is generated, and the session key (S ＊ The data to be transmitted is encrypted using ) - The session key (S ＊ ), encrypted by the disclosed second digital key (S2), and the data encrypted by the session key (S ＊ ) are transmitted to the second terminal device (16). The secret first digital key (S1) obtained from the backend and the secret first digital key (S1) of the signed confirmation certificate (Z ＊＊ ) are used for decryption. If the verification ends unsuccessfully, information is notified to the first terminal device (14). On the other hand, if the verification is successful, the data is decrypted using the session key (S ＊ ) A method characterized by the following features.

2. The generation of the secret first digital key (S1), the publicly disclosed 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). The method according to claim 1, characterized in that

3. The publicly disclosed second digital key (S2) is encrypted and stored in memory outside the network. The method according to claim 1, characterized in that

4. In addition to being stored in the backend, the secret first digital key (S1) is further stored encrypted in memory outside the network. The method according to claim 1, characterized in that

5. The aforementioned publicly disclosed second digital key (K2) is initially stored in each of the terminal devices (14, 16). The method according to claim 1, characterized in that

6. A counter counts consecutive unsuccessful attempts. The method according to claim 1, characterized in that

7. If the count in the counter exceeds a predetermined value, at least one warning signal is triggered. The method according to claim 6, characterized in that

8. The aforementioned confirmation certificate (Z ＊ The validity period of ) is set. The method according to claim 1, characterized in that

9. The aforementioned signed confirmation certificate (Z ＊＊ The validity period of ) is set. The method according to claim 1, characterized in that

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

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