Method for encryption transmission of data

Abstract

The invention relates to a method for the encrypted transmission (10) of data between terminals (14, 16), in which, prior to the transmission of the data, a verification certificate (Z *) is created and transmitted to a rear end (12) and is signed in the rear end (12) by a root certificate (Z), the signed verification certificate (Z * *) is sent back to the second terminal (16), and the signed verification certificate (Z * *) is transmitted to the rear end (12). A public second digital key of the signed verification certificate (Z * *) is transmitted to the first terminal (14) and verification is carried out using the public second digital key (S2), during the verification, an encrypted unique symmetric session key (S *) is generated, which is transmitted to the second terminal (16) and is decrypted by means of the private key of the signed verification certificate (Z * *), and in the event of a verification failure, an encrypted unique symmetric session key (S *) is generated, which is transmitted to the second terminal (16) and is decrypted by means of the private key of the signed verification certificate (Z * *). The first terminal (14) is notified, or the data is decrypted using the session key (S *) if the verification is successful.

Description

Technical Field

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

[0002] More and more confidential and personal data is sent back and forth between two or more parties (including technical systems and their subsystems) via IP-based communications and must be protected against eavesdropping and manipulation by unauthorized third parties (including hacker attacks). In embedded systems in particular, highly sensitive data must be protected from unauthorized access during storage and transmission, for example by (English) "Scalable Service-Oriented Middleware over IP" SOME / IP, without requiring a large CPU load.

[0003] For example, vulnerabilities that allow easy access to the keys used to encrypt and decrypt data can compromise the security of the entire system. When information is exchanged over a public network, it passes through several exchange nodes whose reliability may be questionable. Therefore, the data must be fully encrypted by the sender before or during transmission and decrypted after receipt by the recipient. In this case, these parties or endpoints must always have a protected and temporarily exchanged key that allows them to decrypt the corresponding message of the other party, but this key must also be protected from unauthorized access if the encrypted data is obtained by an unauthorized third party exploiting other security vulnerabilities (for example, in the cloud).

[0004] DE10355865B4 discloses a method and chip for encrypting data using a key. In this case, the method allows the use of a symmetric encryption algorithm based on the process principle to encrypt and decrypt data using a key. Similarly, for the prior art, this example is based on a new method of using a key implemented in a new chip. The so-called BAPA chip that implements this method in hardware is a new key chip that supports the entire field of electronic data communications. However, the disadvantage is that the hardware-related encryption and processing performed by these or other chips cannot be integrated into every embedded system, especially if the existing embedded system no longer allows any changes to the hardware and its architecture.

[0005] Similarly, US20180063094A1 has disclosed "end-to-end encryption for personal communication nodes", which is, accordingly, end-to-end encryption for group communication of personal communication nodes. This is provided by implementing a pairwise encryption process between a pair of end-user devices that are members of a communication group. In this case, the end-user device shares a group key with a paired end-user device. The group key is encrypted by using a message key created using a pairwise encryption process. When a transmission member in the group communicates with a member, it generates a stream key and encrypts the stream data with the stream key, encrypts the stream key with the group key, and then transmits the encrypted stream key and the encrypted stream data to the group member. The main disadvantage of this method is that the communication group must be registered in the server with its identity and public key in advance. For encrypted communication, a secure connection between a pair of end-user devices must be actively established in advance. The message key is not encrypted and can therefore be obtained by unauthorized third parties, including hackers.

[0006] Furthermore, CA 2703 612A1 discloses a secure logical communication link between a secure payment module and a controller for secure communication in a retail environment, the secure logical communication link being generated by employing key authentication of a device processing sensitive information in the retail environment. Summary of the invention

[0007] The object of the present invention is to further develop a method for encrypted transmission of data in such a way that the data are particularly strongly protected.

[0008] This object is achieved according to the invention by a method having the features of claim 1. Advantageous embodiments with advantageous developments of the invention are the subject matter of the dependent claims.

[0009] One aspect of the invention relates to a method for encrypted transmission of data between a first terminal transmitting data and at least one second terminal receiving data via a network. In this case, the network and the terminal have all the components required for the transmission of data, which makes communication between the terminal and the back end of the network possible. The method comprises a plurality of method steps, wherein, in a first method step, the generation of a private first digital key and a public second digital key and a root certificate is performed. The two keys are generated corresponding to each other and authenticated with a root certificate. A root certificate is a certificate signed by the certificate authority itself. It is used to verify the validity of all certificates (in this case keys) issued by the certificate authority. In particular, the generation is performed in the back end of the network. In a further method step, protected storage of the private first digital key is first performed in the back end of the network, and individual key copies of the public second digital key are generated and stored for the individual terminals. Then, two identical public second digital keys are directly generated and transmitted or forwarded to the respective terminals, respectively, or these are already pre-installed there, wherein it is also possible to generate one first and then its key copy.

[0010] In order to solve the purpose of the present invention, a method for encrypting and transmitting data is further developed so that the data is particularly strongly protected. According to the present invention, before transmitting data between a first terminal as a sender and a second terminal as a receiver, a verification certificate is created by means of the second terminal, i.e., the receiver terminal, and transmitted to the back end, and signed by the root certificate at the back end. Then the signed verification certificate is sent back to the second terminal, and the public second digital key of the signed verification certificate is sent to the first terminal or the sender terminal respectively, and checked there with the private key copy of the public second digital key. In the case of verification failure, the first terminal or the sender terminal refuses the encrypted transmission of the data. On the other hand, in the case of successful verification, a unique symmetric session key encrypted with the key copy of the public second digital key of the signed verification certificate is generated, and the data to be transmitted is encrypted with the help of this key. Then, the encrypted session key and the data encrypted thereby are transmitted to the second terminal, i.e., the receiver terminal, and decrypted there with the help of the private private first digital key of the verification certificate, whereby the first terminal, i.e., the sender terminal, is notified in the case of verification failure, or in the case of successful verification, the data is decrypted with the session key. Thus, a particularly protected data transmission against unauthorized third parties, including hackers, is provided by means of the session key and the authentication certificate.

[0011] In other words, an embodiment of a method for hybrid end-to-end (E2E) encryption for authentication and authorization of highly sensitive communications between two or more parties, including technical systems, particularly for embedded systems, is provided.

[0012] In this case, a root certificate with a private key and a public key is first generated for a system consisting of a terminal and a network with a backend provided using the method. The private first digital key is stored in the public backend and protected. The public key is initially stored in the terminal or pre-installed, for example, in an ECU without a backend connection. If a terminal wants to send highly sensitive data "pushed" to another terminal or is requested to do so "pulled" by another terminal, it requests "pushing" or receives "pulling" a unique verification certificate with a public key from the receiving terminal, which is signed with the root certificate by the backend. In addition, the signature and validity period of the verification certificate are checked by the sender terminal using the public key of the root certificate. In the case of a match, and therefore in the case of successful verification, the further steps of the method are initiated, otherwise the receiving terminal is rejected. In addition, a unique symmetric session key is generated, which encrypts the highly sensitive data to be sent, wherein the session key is encrypted with the public key of the verification certificate. The encrypted highly sensitive data and the encrypted session key are then transmitted to the recipient terminal. Finally, the recipient terminal decrypts the session key with the private first digital key of the verification certificate, if the signature and validity period match, the further method steps are initiated, and the highly sensitive data are decrypted with the session key. In case of a matching failure, the sender terminal is informed by means of a signal.

[0013] In an advantageous embodiment of the invention, the generation of the private first digital key and the public second digital key and the root certificate is triggered by means of a command transmitted from one of the terminals to the backend. This means that the terminal is designed to transmit this command at any time by input, so that the transmission of data can be started by the user of the terminal. Alternatively, the generation can also be triggered by a command from another node of the server (for example, from a partially autonomous or autonomous terminal).

[0014] Another embodiment of the invention is advantageous in which the public second digital key is protected in another memory outside the network. For example, the public second digital key thus generated and transmitted to the respective terminal can be transmitted to a memory coupled to the terminal, as a result of which the key is not lost in the event of a defect in the terminal. In particular, storing the key in a memory outside the network ensures the security of the key and avoids the generation of new keys, as a result of which, for example, the working memory requirement in the method is at least partially reduced.

[0015] In another advantageous embodiment of the invention, it is provided that the private first digital key is stored in a protected manner in a memory external to the network. In this case, the external storage enables the data stored on the back end to also remain protected in another memory. This is particularly advantageous when using a third-party network provider, since the network external memory can be closed, for example, at the OEM, so that a backup of the key is achieved and can only be provided by the OEM.

[0016] In a further advantageous embodiment of the invention, the public second digital key is initially stored in each terminal. This not only avoids the generation of a unique key, but also the unique key is only assigned to this one terminal, as a result of which, for example, a simplified and still secure encryption is provided by an already performed encryption process without having to provide a working memory for new keys. The public second digital key is initially stored in the terminal or, for example, preinstalled in an ECU without backend connection. The root certificate can be started for a longer period of time, for example more than 20 years, and renewed if necessary.

[0017] Also advantageous is a design of the invention in which a counter is used to continuously count the failed verifications. In this case, the counter should always be triggered when the counter fails the verification for various reasons. In this case, the reasons can be classified and the data on the failures can be stored for statistical evaluation and improvement. Likewise, different counters can be combined in the method to collect different data and information.

[0018] Another embodiment of the invention is also advantageous, in which at least one warning signal is triggered if the count of the counter is higher than a predetermined value. In particular, login attempts by third parties as well as hacker attacks should be immediately recognized and forwarded to the network. Thus, possible unauthorized interventions can be immediately prevented so that no transmission occurs.

[0019] In other advantageous designs of the invention, a validity period of the verification certificate or the signed verification certificate is provided and the encrypted transmission is limited in time. In particular, if the backend connection with the backend is successful and the communication is carried out via a public network, the validity period of the verification certificate will be greatly shortened, depending on the application, to a maximum of one day or even to two hours to avoid unauthorized interception of data by hackers and the like. The time limit of the method also allows data to be transmitted for a period of time and then interrupted after the expiration of a predetermined time. This avoids unauthorized interference with the transmission.

[0020] Particularly advantageous are:

[0021] - Through the root certificate and the verification certificate (authenticated and authorized), it is ensured that the sender terminal can only verify the signature and validity period of the verification certificate successfully with the root certificate (i.e., from an authorized terminal)

[0022] Only transmit highly sensitive data when

[0023] - Through the authentication certificate (authenticated) generated for the current communication session, ensure that highly sensitive data is encrypted and decrypted with the session key protected by the authentication certificate.

[0024] -Symmetric session keys encrypted or decrypted with asymmetric authentication keys can encrypt or decrypt highly sensitive data in embedded systems without requiring significant CPU load.

[0025] - If an endpoint or component (e.g. an ECU in an embedded system without backend connection) needs to send highly sensitive data to another endpoint or component in a protected manner, this can also be done without backend connection, but must use previously authenticated certificates that are still valid,

[0026] This is possible in protected embedded systems with longer validity periods.

[0027] - If the backend connection is successful and the communication runs over a public network, the validity period of the verification certificate will be significantly shortened, up to one day or even 2 hours depending on the application, to avoid unauthorized replay by hackers.

[0028] -Other endpoints or components can be more easily plugged into the protected system through their dedicated authentication certificates and public root certificates. DETAILED DESCRIPTION

[0029] Further advantages, features and details of the invention are given in the following description of preferred embodiments and with reference to the drawings. The above features and combinations of features mentioned in the description, as well as the features and combinations of features mentioned in the description of the drawings and / or shown alone in the drawings, can be used not only in the respective combination but also in other combinations or alone without departing from the scope of the invention.

[0030] In this case, a single Figure 1 A possible example is shown for illustrating the method according to the invention for encrypted data transmission 10 , in particular by means of hybrid E2E encryption and authentication.

[0031] In this example, a network is shown with a backend 12, a first terminal 14 and a second terminal 16. The backend 12 is accessible to registered terminals, namely the first and second terminals 14, 16. In the example, the first terminal 14 is shown as a sender and the second terminal 16 is shown as a receiver.

[0032] Figure 1A loop is shown with a request method, which starts with an initialization 20 in order to generate a root certificate Z (not shown) and a private first digital key S1 (not shown) and a public second digital key S2 (not shown), respectively. The public second digital key S2 is copied in such a way that a first key copy K1 and a second key copy K2 are generated, respectively, in order to forward them to all terminals 14, 16 and to encrypt and protect the authorized transmission of highly sensitive data. Thus, in an initialization 22, a public root certificate Z is generated, and a protected private first digital key S1 is generated. Subsequently, the key copy K1 is sent 24 to the first terminal 14 and the key copy K2 is sent 26 to the second terminal 16.

[0033] Next comes a sequence 28 with a substitution request between the first terminal 14 and the second terminal 16, wherein a request 30 for sending highly sensitive data (pull data) is triggered by the second terminal 16. This is followed by a request 32 for the public second digital key S2 or key copy K1 for a verification certificate Z* for sending highly sensitive data (push) via the first terminal 14. In case a backend connection is not available, for example for an embedded component without a backend connection, a valid verification certificate Z* needs to be reused 33 in order to be initialized in this case.

[0034] Thereafter, generation 34 of the verification certificate Z* is performed on the second terminal 16 and subsequently a request 36 is initiated at the backend 12 to sign the verification certificate Z* with a root certificate, i.e. the root certificate Z. Thereafter, the signed verification certificate Z** is sent back 38 from the backend 12 to the second terminal 16. A transmission 40 occurs. In this case, the second terminal 16 sends back to the first terminal 14 the public second digital key S2 for the signature of highly sensitive data or a key copy K1 of the signed verification certificate Z**.

[0035] The steps of the first terminal 14 are as follows:

[0036] In a first step 42 , the validity of the signature and the signed verification certificate Z** are checked respectively with the public second digital key S2 and the key copy K1 of the root certificate Z. If the verification is not OK, a stop 46 occurs, in which the process stops and the recipient, ie the second terminal 16 , is notified.

[0037] - In a second step 44, a random session key, ie a unique symmetric session key S*, is generated.

[0038] - In a third step 48, all highly sensitive data are encrypted with the session key S*.

[0039] - In a fourth step 50, the session key S* is encrypted with the public second digital key S2 or the key copy K1 of the signed verification certificate Z**, respectively.

[0040] Finally, in a fifth step, the first terminal 14 transmits 52 the encrypted data and the session key S* to the second terminal 16, and a corresponding decryption 54 is performed. In this case, the second terminal 16 decrypts the session key S* with the private first digital key S1 of the authentication certificate Z*. If the decryption fails, a stop 58 occurs, in which the process stops and the sending first terminal 14 is notified. Otherwise, a decryption 56 occurs, in which the second terminal 16 decrypts the highly sensitive data with the session key S*. This completes the method for encrypted transmission of data.

[0041] In other words, Figure 1 A method for encrypting and transmitting data between terminals 14 and 16 via a network is provided, the method comprising the steps of:

[0042] - Generate a private first digital key S1 and a public second digital key S2 and a root certificate Z;

[0043] - protected storage of the private first digital key S1 in the backend 12 of the network; and

[0044] - generating and storing respective key copies K1, K2 of the common second digital key S2 in the respective terminals 14, 16;

[0045] In this case, it is provided that before transmitting data with the aid of the second terminal 16 (receiver terminal), a verification certificate Z* is created and transmitted to the back end 12, and is signed in the back end 12 by the root certificate Z. Thereafter, the signed verification certificate Z** is transmitted to the first terminal 14, and is verified by the first terminal 14 (sender terminal) with a private key copy K1 of the public second digital key S2, whereby, in the case of a verification failure, the encrypted transmission of the data is rejected, or, in the case of a successful verification, a unique symmetric session key S* encrypted with the key copy K1 of the public second digital key of the signed verification certificate Z** is generated. In addition, the session key S* is transmitted to the second terminal 16, and is decrypted with the aid of the private private first digital key S1 of the signed verification certificate Z**, whereby the first terminal 14 is notified in the case of a verification failure, or, in the case of a successful verification, the data is decrypted with the session key S*.

[0046] The generation of the private first digital key S1 and the public second digital key S2 and the root certificate Z can also be started by means of a command transmitted from one of the terminals 14, 16 to the back end 12. Likewise, the public second digital key S2 is stored in an encrypted manner in a memory outside the network. In addition, the private first digital key S1 can be stored in an encrypted manner in a memory outside the network. In addition, the public second digital keys K1 and K2 are initially stored in the terminals 14, 16, respectively.

[0047] In the event of failed verifications one after another, these verifications can be counted by a counter and, in the event that the count of the counter exceeds a predetermined value, at least one warning signal can be triggered.

[0048] Likewise, the validity period of the verification certificate Z* can be specified relative to the signed verification certificate Z** and the encrypted transmission is limited in time.

[0049] Reference numerals list

[0050] 10Encrypted transmission

[0051] 12 Backend

[0052] 14First Terminal

[0053] 16 Second Terminal

[0054] 20 Initialization

[0055] 22 Initialization

[0056] 24Send

[0057] 26Send

[0058] 28 Sequence

[0059] 30 requests

[0060] 32 Requirements

[0061] 33 Reuse

[0062] 34Generate

[0063] 36 requests

[0064] 38Send back

[0065] 40Transmission

[0066] 42First Step

[0067] 44Step 2

[0068] 46 Stop

[0069] 48 Step 3

[0070] 50 Step 4

[0071] 52Transmission

[0072] 54 Decryption

[0073] 56 Decryption

[0074] 58 Stop

[0075] K1 First key copy

[0076] K2 Second key copy

[0077] S1 First Key

[0078] S2 Second Key

[0079] S*Session Key

Claims

1. A method for encrypting and transmitting (10) data over a network between a first terminal (14) transmitting the data and at least one second terminal (16) receiving the data, comprising the following steps: - Generate a private first digital key (S1) and a public second digital key (S2) and a root certificate (Z); - protected storage of said private first digital key (S1) in a backend (12) of said network; and - generating and storing respective key copies (K1, K2) of said common second digital key (S2) for respective terminals (14, 16) and transmitting said respective key copies (K1, K2) to said respective terminals (14, 16); It is characterized in that - before transmitting data, creating a verification certificate (Z*) by means of the second terminal (16) and transmitting it to the back end (12), and the verification certificate being signed in the back end (12) by the root certificate (Z); - sending the signed verification certificate (Z**) back to the second terminal (16), transmitting the public second digital key (S2) of the signed verification certificate (Z**) to the first terminal (14), and verifying it with the private key copy (K1) of the public second digital key (S2), wherein, in the event of a verification failure, the first terminal (14) rejects the encrypted transmission of data, or, in the event of a verification success, generates a unique symmetric session key (S*) encrypted with the key copy (K1) of the public second digital key (S2) of the signed verification certificate (Z**), and encrypts the data to be transmitted with the help of the key; - The encrypted session key (S*) and the data encrypted thereby are transmitted to the second terminal (16) and decrypted with the aid of a dedicated private first digital key (S1) of the signed authentication certificate (Z**), wherein in the event of a failed authentication, the first terminal (14) is notified, or in the event of a successful authentication, the data are decrypted with the session key (S*).

2. The method according to claim 1, It is characterized in that The generation of the private first digital key (S1) and the public second digital key (S2) and the root certificate (Z) is initiated by means of a command transmitted from one of the terminals (14, 16) to the back end (12).

3. The method according to claim 1 or 2, It is characterized in that The public second digital key (S2) is stored in an encrypted manner in a memory external to the network.

4. The method according to any one of the preceding claims, It is characterized in that The private first digital key (S1) is stored in an encrypted manner in a memory external to the network.

5. The method according to any one of the preceding claims, It is characterized in that The public second digital key (S2) is initially stored in the terminal (14, 16).

6. The method according to any one of the preceding claims, It is characterized in that Use a counter to continuously count failed authentications.

7. The method according to claim 6, It is characterized in that In case the count of the counter is higher than a predetermined value, at least one warning signal is triggered.

8. The method according to any one of the preceding claims, It is characterized in that A validity period of the authentication certificate (Z*) is predetermined.

9. The method according to any one of the preceding claims, It is characterized in that The validity period of the verification certificate (Z**) of the intended signature.

10. The method according to any one of the preceding claims, It is characterized in that Encrypted transmissions are limited in time.

Images