EP3877935A1

EP3877935A1 - Method for operating a distributed database system, distributed database system, and industrial automation system

Info

Publication number: EP3877935A1
Application number: EP19812694.8A
Authority: EP
Inventors: Markus Dichtl
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2018-12-21
Filing date: 2019-11-13
Publication date: 2021-09-15
Also published as: US20220067727A1; WO2020126236A1; EP3671599A1; CN113508407A

Abstract

A method for operating a distributed database system (1) having distributed node devices (2 - 6) for providing interlinked data blocks (Bi), in particular in the style of a blockchain (BC), that document transactions between subscribers (8), wherein transactions (TD) between subscribers (8) are protected by means of transaction data and a cryptographic signature process, involves the cryptographic signature process being defined for each transaction in order to protect the respective transaction, wherein signature information identifying the defined cryptographic signature process is part of the transaction or part of a performance request for the transaction. For each transaction, signature data are then calculated using the defined cryptographic signature process for at least some of the transaction data or the hash value thereof, and the signature data are added to the transaction data.

Description

description

Method for operating a distributed database system, distributed database system and industrial automation system

The present invention relates to a method for operating a distributed database system, such as a block chain (blockchain) with the aid of networked node devices. Such a database system is particularly suitable for use in an industrial automation network. In order to be able to carry out and document data entries or transactions within a block chain, such entries are cryptographically secured. For example, it is common to digitally sign transactions or entries according to a specified standard.

With the well-known block chain Bitcoin, which manages a cryptocurrency, participants or users can have monetary entries in the Bitcoin block chain with the help of their private cryptographic keys. The cryptographic method for securing the respective database entries for persons or participants is based on elliptic curve cryptography (ECC) with a specific key length, namely 256 bits. The

The key length of the ECDSA signatures used (Elliptic Curve Digital Signature Algorithm: ECDSA) was chosen so that a manipulative attack is improbable to impossible. Since future computer services that can be used to attack such distributed database systems are not foreseeable, it is questionable whether the Bitcoin block chain will be equipped with an appropriate security level in the long term.

For the bitcoin blockchain, it is planned that the last bitcoins will be created in 2130. It is highly probable that elliptic curves with a 256-bit module are not adequate at this point Security will offer more. The doubts about the long-term security of these curves are reinforced by the current advances in quantum computers. A conceivable quantum computer with a sufficient number of quantum bits could break all the usual cryptographic methods based on elliptic curves in polynomial time.

In this respect, it is desirable to keep the security and robustness of distributed database systems as high and flexible as possible against cryptoanalytic attacks.

Against this background, it is an object of the present invention to enable improved operation of distributed database systems, in particular of block chains.

The object is achieved by the features given in the independent claims. Advantageous developments of the invention are shown in the dependent claims.

Accordingly, a method is provided for operating a distributed database system with distributed node devices for providing linked data blocks. The data blocks can in particular be provided in the manner of a block chain. The data blocks document transactions between participants, transactions between participants being secured with the aid of corresponding transaction data and a cryptographic signature process. The procedure is for everyone

Transaction defines the cryptographic signature method for securing the respective transaction, wherein a signature information identifying the specified cryptographic signature method is part of the transaction data or part of an execution request for the transaction.

In particular, signature data is calculated for each transaction according to the specified cryptographic signature method over at least part of the transaction data. ten or its hash value, and the signature data is added to the transaction data.

The cryptographic signature creates a cryptographic link or coupling between the participant and a requested transaction or the respective data entry and thereby meets certain security requirements. An example of a security level is, for example, a key length.

By defining the cryptographic signature procedure to be used in the context of - preferably - every transaction or confirmation, the operation of the database system becomes more flexible and secure. It is possible to change the security level of the signature process over the life of the database system and to adapt it to the progress of cryptanalysis.

In the case of security methods which are based on secret information, such as, for example, a cryptographic private key, the security level can be the average number of elementary operations which the most efficient known algorithm requires in order to determine the secret information. With a security level of 80 bits, an attacker 2 has to perform ⁸⁰ elementary operations to find the private key. You can then say that the security level is 80 bits. Other measures for the respective security level, such as a key length or a parameter of elliptical curves, are also conceivable.

The security level is determined by using a specific cryptographic signature procedure, for example, for all future transactions as long as no new cryptographic signature procedure is established, in particular with increased security. Preferably, without specifying the signature information, for example in the manner of a reference, pointers, program codes for the signature to be used procedure and / or a parameter for the signature procedure, no transaction can be carried out.

In embodiments, the signature information has a program code for performing the specified cryptographic signature method. The cryptographic signature process can be implemented as executable code and stored in the database system. A possible implementation of the method provides for one or more smart contracts that trigger a corresponding cryptographic or different cryptographic signature method. In this respect, variants of the method provide that a predefinable cryptographic signature method in the manner of a smart contract is provided for or in the distributed database system.

It is also conceivable that the signature information has a pointer to a program code for executing the specified cryptographic signature method.

In one embodiment of the method, the signature information is digitally signed using the defined cryptographic signature method. Alternatively, a hash value for the signature information can first be generated, and then the hash value can be digitally signed using the specified cryptographic signature method. The signed and / or hashed signature information is then added to the transaction data.

The respective signature is preferably part of a transaction or transaction request or the transaction data.

For example, in a change transaction, a new cryptographic signature process can be defined for all subsequent transactions to secure the respective transaction. In particular, this only occurs if a specified proportion of participants in a change transaction under fertilizes the currently specified cryptographic signature procedure.

In embodiments, all participants in the database system must agree. It is also possible to use a predetermined necessary majority, e.g. two thirds or 50% to determine to change the signature process.

In embodiments, a group of participants can agree on a specific digital signature method for transactions among participants in the group and can determine future transactions.

In embodiments, the cryptographic signature method to be used is determined for a certain period of time. It is also conceivable to define the signature method for a maximum number of transactions, it having to be redetermined after the period or the number of transactions.

In embodiments, a new specified signature method must have a higher cryptographic security level than the currently specified signature method.

In embodiments, the respective cryptographic signature method links a cryptographic key pair to one another, with each participant being assigned a valid key pair. Alternatively or additionally, the signature method can be implemented with elliptic curve cryptography (ECC).

With ECC, discrete log problems are considered and the curve parameters are defined. The security level of an ECC is essentially determined by the key length. In relation to a distributed database system and the cryptographic binding of data entries to participants, the security level of the specified cryptographic signature procedure can be the key length used. The cryptographic signature method can be implemented on the basis of an elliptic curve cryptography (ECC), and the signature information has, for example, the key length for the ECC, in particular as the number of bits.

The cryptographic signature method is preferably implemented on the basis of post-quantum cryptography (PQC). The definition of a PQC method enables protection against attacks with the help of quantum computers, which may be able to decrypt asymmetric cryptosystems that have been used up to now. Therefore, during the operation of the distributed database, a previous cryptographic signature method can be replaced by a new signature method that is more robust with regard to quantum computer attacks. In particular, it is conceivable to specify a method according to the RFC 8391 standard in the version at the time of filing this patent application. XMSS is particularly suitable as a signature method.

In embodiments it is provided that the interlinked data blocks, which document transactions between participants, comprise data blocks which are secured with the aid of different cryptographic signature methods.

In particular, a block chain operated with the aid of the proposed method can include transactions with signatures of different security levels. Old data records that are endangered and documented in data blocks can be saved by transferring them to newer data blocks that are protected according to the currently defined signature procedure.

The cryptographic signature method, in particular, cryptographically links a cryptographic key pair to one another. A current key pair can then be assigned to each subscriber. In embodiments, it is ensured that there is exactly one participant for each key pair. In principle, participants can also have several key pairs.

In embodiments of the method, at least one of the following steps is also carried out for each participant:

Assigning a digital signature key to the subscriber, the digital signature key corresponding to the currently defined cryptographic signature method; digitally signing a transaction request from the subscriber using the digital signature key assigned to the subscriber to generate a digitally signed transaction request; and

Confirm the transaction if the digital signature is recognized as valid and if the transaction with a transaction history of the block chain as a distributed database system is free of contradictions.

A digital signature key can also be assigned by the respective subscriber himself. For example, a participant generates the key pair that he uses.

In embodiments, the linked data blocks document transactions relating to a resource, in particular a cryptocurrency. A security level of the cryptographic signature process is then determined in particular as a function of a value or an amount of the resource documented in the context of the transaction. In this respect, the transaction security can be adjusted to the value of the transaction.

In the method, the linked data blocks can document transactions relating to a resource, in particular a cryptocurrency, and the transaction is carried out by checking the signature in the transaction data by checking bodies. A quantity of the managed resource is then to be transferred to the verification instances for the verification, the quantity depending on the calculation effort of the Signature verification depends. Network devices that provide computing power for the cryptographic calculations in accordance with the specified signature method can be used as the checking entity. For example, the greater the calculation effort, the greater the transaction costs are determined. This can be used to prevent denial of service attacks in particular.

In embodiments, operation beyond the above-mentioned steps is performed in accordance with a known block chain algorithm. For example, Ethereum, IOTA or Bitcoin variations are conceivable.

A distributed database system is also proposed, which comprises a plurality of node devices for providing interconnected data blocks, which are linked in particular in the manner of a block chain. Each node device is set up to document transactions between participants in accordance with a predetermined block chain algorithm, the block chain algorithm causing the node devices to carry out a method described above and below.

In particular, a node device is proposed which is set up in such a way that it can be used as a node device in a distributed database system and operates in accordance with the block chain algorithm as described above and below.

Furthermore, an industrial automation network with a distributed database system as described above and below is proposed, the database system being set up for documenting and controlling transactions for field devices in the automation network.

In particular, field devices which are provided with addresses can be considered as subscribers. Such field devices can generate sensor data or control data, which can be fe of the node devices can be stored distributed. Since only digitally signed transaction inquiries are used to carry out transactions, the security of such industrial automation networks can be improved. The field devices can also represent node devices themselves in the database system.

The technology of block chains or blockchains

"Distributed Ledgers" is currently an intensely discussed technology that can be implemented in particular as a distributed database system. In addition to applications for decentralized payment systems (e.g. Bitcoin), new applications are being developed in the financial industry. In particular, transactions between companies can be realized without manipulation or a clearing house.

This enables new business models without a trustworthy intermediary, reduces transaction costs, and new digital services can be offered flexibly, usually without a specially set up infrastructure and trust relationships. A transaction record (or short transaction) protected by a blockchain includes e.g. B. Program code, which can also be referred to as a so-called "smart contract".

The respective unit, for example a node, a computing unit or control unit, can be implemented in terms of hardware and / or software. In a hardware implementation, the respective unit can be designed as a device or as part of a device, for example as a computer or as a microprocessor or as a control computer of a vehicle. In a software implementation, the respective unit can be designed as a computer program product, as a function, as a routine, as part of a program code or as an executable object. Furthermore, a computer program product is proposed which causes the execution of the method as explained above on one or more program-controlled devices.

A computer program product, such as a computer program means, for example as a storage medium, e.g.

Memory card, USB stick, CD-ROM, DVD, or also in the form of a downloadable file from a server in a network. This can be done for example in a wireless communication network by transferring a corresponding file with the computer program product or the computer program means.

The embodiments and features described for the proposed device apply accordingly to the proposed method.

Further possible implementations of the invention also include combinations of features or embodiments described above or below with reference to the exemplary embodiments that are not explicitly mentioned. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

Further advantageous embodiments and aspects of the inven tion are the subject of the dependent claims and the embodiments of the invention described below. In Wei teren the invention is based on preferred embodiments with reference to the accompanying figures, he explained.

Unless otherwise stated in the following description, the terms “perform”, “calculate”, “computer-aided”, “calculate”, “determine”, “generate”, “configure”, “reconstruct” and the like preferably on actions and / or processes and / or processing steps that change and / or generate data and / or convert the data into other data, the data being represented or being able to be present in particular as physical quantities, for example as electrical impulses. In particular, the expression “computer” should be interpreted as broadly as possible, in particular to cover all electronic devices with data processing properties . Computers can thus be, for example, personal computers, servers, programmable logic controllers (PLCs), handheld computer systems, pocket PC devices, mobile radio devices and other communication devices which can process data with computer support, processors and other electronic devices for data processing .

In the context of the invention, “computer-assisted” can be understood to mean, for example, an implementation of the method in which, in particular, a processor executes at least one method step of the method.

A processor can be understood in connection with the invention, for example, a machine or an electronic circuit device. A processor can in particular be a main processor (English: Central Processing Unit, CPU), a microprocessor or a microcontroller, for example an application-specific integrated circuit or a digital signal processor, possibly in combination with a memory unit for storing program instructions, etc. act. A processor can also be, for example, an IC (Integrated Circuit), in particular an FPGA (Field Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit), or a DSP (digital signal

processor, engl. Digital Signal Processor) or a graphics processor GPU (Graphic Processing Unit). A processor can also be understood to mean a virtualized processor, a virtual machine or a soft CPU. For example, it can also be a programmable processor that can be configured with configuration steps tion of the method according to the invention is configured or is configured with configuration steps in such a way that the programmable processor realizes the features according to the invention of the method, the component, the modules, or other aspects and / or partial aspects of the invention.

A “storage unit” or “storage module” and the like can be understood in connection with the invention, for example, as volatile memory in the form of random access memory (RAM) or permanent storage such as a hard disk or a data carrier.

In the context of the invention, a “module” can be understood to mean, for example, a processor and / or a memory unit for storing program instructions. For example, the processor is specifically designed to execute the program instructions in such a way that the processor executes functions in order to carry out the inventive To implement or implement the method or a step of the method according to the invention A module can, for example, also be a node of the distributed database system which, for example, implements the specific functions / features of a corresponding module For this purpose, the corresponding modules can, for example, comprise further elements, which are, for example, one or more interfaces (eg database interfaces, communication interfaces - eg network interface, WLAN interface) and / or egg ne evaluation unit (e.g. B. a processor) and / or a storage unit. For example, data can be exchanged using the interfaces (e.g.

B. received, transmitted, sent or provided who). Using the evaluation unit, data can be compared, checked, processed, assigned or calculated, for example in a computer-assisted and / or automated manner. By means of the storage unit, data can be stored, called up or made available, for example, computer-aided and / or automatically. Under “include”, in particular with regard to data and / or information, in connection with the invention, for example, a (computer-assisted) storage of a corresponding piece of information or a corresponding date in a data structure / data record (which, for example, in turn in a storage unit is stored) can be understood.

Under “assign”, in particular with regard to data and / or information, in connection with the invention, for example, a computer-assisted assignment of data

and / or information can be understood. For example, a first date is assigned a second date using a memory address or a unique identifier (UID), in which e.g. B. the first date is stored together with the memory address or the unique identifier of the second date together in a data set.

“Provision”, in particular with regard to data and / or information, can be understood in connection with the invention to mean, for example, computer-assisted provision. The provision is carried out, for example, via an interface (for example a database interface, a network interface, an interface to a storage unit) This interface can be used, for example, to transmit and / or send and / or retrieve and / or receive corresponding data and / or information.

In connection with the invention, “providing” can also be understood, for example, to mean loading or storing, for example a transaction with corresponding data. This can be done, for example, on or from a memory module. “Providing” can also be used, for example, to transfer (or sending or transmitting) corresponding data from one node to another Nodes of the block chain or of the distributed database system (or their infrastructure) can be understood.

In the context of the invention, a “smart contract process” can be understood in particular to mean executing a program code (for example the control commands) in a process through the distributed database system or its infrastructure.

A “checksum”, for example a data block checksum, a data checksum, a node checksum, a transaction checksum, a chaining checksum or the like, can be understood in the context of the invention, for example, to be a cryptographic checksum or cryptographic hash or hash value, which in particular by means of cryptographic hash function via a data record and / or data and / or one or more of the transactions and / or a partial area of a data block (e.g. the block header of a block of a block chain or data block header of a data block of the distributed database system or only a part the transactions of a data block) are formed or calculated. A checksum can in particular be a checksum or hash value (s) of a hash tree (eg Merkle Baum, Patricia-Baum) a digital signature or cryptographic message authentication code can be understood. By means of the checksums, for example, a cryptographic one can be made at different levels of the database system

Protection / manipulation protection for the transactions and the data (records) stored therein can be implemented. For example, if a high level of security is required, the checksums are generated at the transaction level and checked. If less security is required, the checksums are generated and checked at block level (e.g. over the entire data block or only over part of the data block and / or part of the transactions).

In the context of the invention, a “data block checksum” can be understood to mean a checksum which for example, it is calculated over part or all of the transactions in a data block. A node can then, for example, check / determine the integrity / authenticity of the corresponding part of a data block using the data block checksum. Additionally or alternatively, the data block checksum can in particular also have been formed via transactions of a previous data block / predecessor data block of the data block. The data block checksum can in particular also be implemented by means of a hash tree, for example a Merkle tree [1] or a Patricia tree, the data block checksum in particular the root checksum of the Merkle tree or a Patricia tree or of a binary hash tree. In particular, transactions are secured by means of further checksums from the Merkle tree or Patricia tree (e.g. using the transaction checksums), the further checksums in particular being leaves in the Merkle tree or Patricia tree. The data block checksum can thus secure the transactions, for example, by forming the root checksum from the further checksums. The data block checksum can in particular be calculated for transactions of a specific data block of the data blocks. In particular, such a data block checksum can be included in a subsequent data block of the specific data block in order to chain this subsequent data block, for example, with its previous data blocks and in particular thus to make it possible to check the integrity of the distributed database system. As a result, the data block checksum can, for example, take on the function of the chaining checksum or be included in the chaining checksum. The header of a data block (e.g. a new data block or the data block for which the data block check sum was formed) can comprise, for example, the data block check sum.

“Transaction checksum” can be understood in connection with the invention as a checksum that is formed in particular via a transaction of a data block. In addition, for example, a calculation of a data block checksum for a corresponding data block can be accelerated, since for this purpose, for example, transaction checksums that have already been calculated immediately as sheets z. B. a Merkle tree can be used.

In the context of the invention, a “chaining checksum” can be understood to mean a checksum which is determined or is referenced in particular for a respective data block of the distributed database system with the aid of the preceding data block of the distributed database system (in the specialist literature in particular) often referred to as "previous block hash") [1]. For this purpose, a corresponding chaining checksum is formed, in particular for the corresponding preceding data block. A chaining checksum or, for example, the data block checksum of a data block (that is, an existing data block of the distributed database system) can be used as the chaining checksum in order to chain a new data block with an (existing) data block of the distributed database system. However, it is also possible, for example, for a checksum to be formed via a header of the preceding data block or over the entire previous data block and to be used as a chaining checksum. This can also be calculated for several or all of the previous data blocks, for example. For example, it is also possible to form the chaining checksum via the header of a data block and the data block checksum. However, a respective data block of the distributed database system preferably comprises a chaining checksum, which was calculated for a previous data block, in particular even more preferably the immediately preceding data block, of the respective data block or refer to it. It is also possible, for example, for a corresponding chaining checksum to be formed only over part of the corresponding data block (e.g. previous data block). In this way, for example, a data block can be realized which comprises an integrity-protected part and an unprotected part. That would leave For example, a data block can be realized whose integrity-protected part cannot be changed and whose unprotected part can also be changed later. In this context, integrity-protected means in particular that a change in integrity-protected data can be determined by means of a checksum.

The data, which are stored, for example, in a transaction of a data block, can in particular be provided in different ways. Instead of the data, e.g. B. user data such as measurement data or Da

ten / ownership of assets, for example, a transaction of a data block can only include the checksum for this data. The corresponding checksum can be implemented in different ways. This can e.g. B. be a corresponding data block checksum of a data block (with the corresponding data) of another database or the distributed database system, a transaction checksum of a data block with the corresponding data (of the distributed database system or another database) or a data checksum that is about the data was formed.

In addition, the corresponding transaction can contain a reference or an indication of a storage location (e.g. an address of a file server and details of where the corresponding data can be found on the file server; or an address of another distributed database which contains the data includes) to include. The corresponding data could then, for example, also be provided in a further transaction of a further data block of the distributed database system (for example if the corresponding data and the associated checksums are contained in different data blocks). For example, it is also conceivable that this data is made available via another communication channel (e.g. via another database and / or a cryptographically secured communication channel). In addition to the checksum, for example, an additional data record (for example a reference or an indication of a storage location) can also be stored in the corresponding transaction, which in particular indicates a storage location where the data can be called up. This is particularly advantageous in order to keep the data size of the block chain or the distributed database system as small as possible.

In the context of the invention, “security-protected” can be understood to mean, for example, protection that is implemented in particular by a cryptographic method. For example, this can be done by using the distributed database system for the provision or transmission or transmission of corresponding data / transactions reali be Siert. this is preferably achieved by a combination of different (cryptographic) checksum by usammenwirken this particular synergy _Z to improve in play, the safety or the cryptographic assurance regarding data on the transactions. with ande ren words may in particular “Security-protected” in connection with the invention also means “cryptographically protected” and / or “manipulation-protected”, wherein “manipulation-protected” can also be referred to as “integrity-protecting”.

In the context of the invention, “chaining / of data blocks of a distributed database system” can be understood, for example, to mean that data blocks each comprise information (for example, chaining checksum) which refer to another data block or to several other data blocks of the distributed database system or reference these [1] [4] [5].

“Inserting into the distributed database system” and the like can be understood in connection with the invention, for example, that in particular a transaction or the transactions or a data block with its transactions to one or more nodes of a distributed database. Systems is transmitted. If, for example, these transactions are successfully validated (e.g. by the node (s)), these transactions are linked in particular as a new data block with at least one existing data block of the distributed database system [1] [4] [5]. For this purpose, the corresponding transactions are stored in a new data block, for example. In particular, this validation and / or chaining can be carried out by a trustworthy node (for example a mining node, a block chain oracle or a block chain platform). In particular, a block chain platform can be understood to mean a block chain as a service, as is proposed in particular by Microsoft or IBM. In particular, a trustworthy node and / or a node can each store a node checksum (e.g. a digital signature) in a data block (e.g. in the data block they have validated and generated, which is then linked) in order to in particular to enable the creator of the data block to be identified and / or to enable the node to be identified. This node checksum specifies which node, for example, has linked the corresponding data block to at least one other data block of the distributed database system.

In the context of the invention, “transaction” or “transactions” can be understood to mean, for example, a smart contract [4] [5], a data structure or a transaction data record, each of which in particular comprises one of the transactions or more transactions. In the context of the invention, “transaction” or “transactions” can also be understood to mean, for example, the data of a transaction of a data block of a block chain. In particular, a transaction can include a program code that, for example, implements a smart contract. For example, in connection with the invention, a transaction can also be understood to mean a tax transaction and / or confirmation transaction. Alternatively, a transaction can be, for example, a data structure, the data saves (e.g. the control commands and / or contract data and / or other data such as video data, user data, measurement data, etc.).

In particular, “storing transactions in data blocks”, “storing transactions” and the like is to be understood as direct storage or indirect storage. Direct storage can mean, for example, that the corresponding data block (of the distributed database system) or the corresponding transaction of the distributed database system) comprises the respective data. Indirect storage can be understood, for example, to mean that the corresponding data block or the corresponding transaction comprises a checksum and optionally an additional data record (e.g. a reference or an indication of a storage location) for corresponding data and thus the corresponding data are not stored directly in the data block (or the transaction) (ie instead only a checksum for this data). In particular, when storing transactions in data blocks, these checksums can be validated, for example, as is explained, for example, under “inserting into the distributed database system”.

In the context of the invention, a “program code” (for example a smart contract) can be understood to mean, for example, a program command or a number of program commands that are stored in particular in one or more transactions. The program code can be executed in particular and becomes, for example This can be implemented, for example, by means of an execution environment (for example a virtual machine), the execution environment or the program code preferably being Turing-complete. The program code is preferably carried out by the infrastructure of the distributed Database system [4] [5], where, for example, a virtual machine is implemented by the infrastructure of the distributed database system. A "smart contract" can be understood in connection with the invention as an executable program code, for example [4] [5] (see in particular the definition of "program code"). The smart contract is preferably stored in a transaction of a distributed database system (e.g. a block chain), for example in a data block of the distributed database system. For example, the smart contract can be executed in the same way as is explained in the definition of "program code", in particular in connection with the invention.

“Proof-of-work proof” can be understood in connection with the invention to mean, for example, solving a computation-intensive task that is to be solved in particular depending on the data block content / content of a specific transaction [1] [4] [5 Such a computationally intensive task is also referred to as a cryptographic puzzle, for example.

In the context of the invention, a “distributed database system”, which can also be referred to as a distributed database, for example, can include a decentrally distributed database, a blockchain, a distributed ledger, a distributed storage system, or a distributed ledger Technology (DLT) based system (DLTS), an audit-proof database system, a cloud, a cloud service, a block chain in a cloud or a peer-to-peer database can also be understood, for example different implementations of a block chain or a DLTS can be used, for example, a block chain or a system based on the DLT that uses a Directed Acylic Graph (DAG), cryptographic puzzles, hash graphs or a combination of the implementation variants mentioned [6] [7] Different consensus algorithms can also be implemented, for example a consensus procedure using a cryptographic puzzle, gossip about gossip, virtual voting or a combination of the mentioned procedures (eg Gossip about Gossip combined with Virtual Voting) [6] [7]. Proof-of-stake, proof-of-authority or proof-of-state variants in addition to the proof-of-work implementation for transaction validation are known in particular. If, for example, a block chain is used, this can be implemented in particular by means of a Bitcoin-based implementation or an Ethereum-based implementation [1] [4] [5]. A “distributed database system” can also be understood to mean, for example, a distributed database system, of which at least some of its nodes and / or devices and / or infrastructure are implemented by a cloud. For example, the corresponding components are nodes or devices in the Cloud (eg as a virtual node in a virtual machine) can be implemented using VM goods, Amazon Web Services or Microsoft Azure, for example. Due to the high flexibility of the implementation variants explained, partial aspects of the implementation variants mentioned can also be combined with one another are used, for example, by using a hash graph as a block chain, the block chain itself being able to be blockless, for example.

For example, if a Directed Acylic Graph (DAG) is used, transactions or blocks or nodes of the graph are connected to one another via directed edges. This means in particular that (all) edges (always) have the same direction, similar to z. B. is at the time. Due to the clear, acyclic course of the edges, the chronological sequence of the transactions involved is clearly and reliably determined. Acyclic means in particular that there are no loops when the graph is run through.

The distributed database system can be, for example, a public distributed database system (e.g. a public block chain) or a closed (or private) distributed database system (e.g. a private block chain). If it is, for example, a publicly distributed database system, this means that new nodes and / or devices without credentials or without authentication or without credentials or without credentials can join or be accepted by the distributed database system. In such a case, in particular, the operators of the nodes and / or devices can remain anonymous.

If the distributed database system is, for example, a closed, distributed database system, new nodes and / or devices require, for example, a valid proof of authorization and / or valid authentication information and / or valid credentials and / or valid login information in order to use the distributed one Database system can join or be accepted by this.

A distributed database system can, for example, also be a distributed communication system for data exchange. This can be, for example, a network or a peer-2-peer network.

Under "data block", which can also be referred to as a "link" or "block", depending on the context and implementation, in connection with the invention, for example, a data block of a distributed database system (e.g. a block chain or a peer to peer database), which is implemented in particular as a data structure and preferably comprises one of the transactions or more of the transactions in one implementation. In one implementation, for example, the database (or the database system) can be a DLT-based system (DLTS) or a block chain and a data block is a block of the block chain or the DLTS A data block can, for example, give information about the size (data size in bytes) of the data block, a data block header, a transaction counter and one or more

Transactions include [1]. For example, the data block header can contain a version, a chaining checksum, a data Ten-block checksum, a time stamp, a proof-of-work proof and a nonce (one-time value, random value or counter that is used for the proof-of-work proof) include [1] [4] [5]. A data block can, for example, also be only a specific memory area or address area of the total data which are stored in the distributed database system. This allows, for example, blockless distributed database systems, such as. B. implement the IoT Chain (ITC), IOTA, and Byteball. In particular, the functionalities of the blocks of a block chain and the transactions are combined with one another in such a way that, for. B. the transactions themselves secure the sequence or chain of transactions (of the distributed database system) (in particular, they are stored in a security-protected manner). For this purpose, for example, the transactions themselves can be linked with one another by means of a chaining checksum, in that a separate checksum or the transaction checksum of one or more transactions serves as the chaining checksum, which is also saved in the corresponding new transaction when a new transaction is stored in the distributed database system. In such an embodiment, a data block can, for example, also comprise one or more transactions, in the simplest case, for example, a data block corresponding to a transaction.

In the context of the invention, “nonce” can be understood to mean, for example, a cryptographic nonce (abbreviation for: “used only once” [2] or “number used once” [3]). In particular, a nonce denotes individual numbers or one Letter combination, which is preferably used once in the respective context (e.g. transaction, data transfer).

“Previous data blocks of a (certain) data block of the distributed database system” can be understood in connection with the invention, for example, the data block of the distributed database system, which in particular comprises immediately precedes a (certain) data block. Alternatively, “previous data blocks of a (certain) data block of the distributed database system” can also be understood to mean, in particular, all data blocks of the distributed database system that precede the specific data block. As a result, the chaining checksum or the transaction checksum can only be used, for example, only via the one directly preceding the particular data block Data block (or their transactions) or over all data blocks preceding the first data block (or their transactions) are formed.

A “block chain node”, “node”, “node of a distributed database system” and the like can be understood in connection with the invention to mean, for example, devices (for example field devices, mobile telephones), computers, smartphones, clients or subscribers which carry out operations (with) the distributed database system (e.g. a block chain) [1] [4] [5] Such nodes can, for example, execute transactions of a distributed database system or its data blocks or new data blocks with new transactions insert or chain into the distributed database system by means of new data blocks, in particular this validation and / or chaining can be carried out by a trustworthy node (eg a mining node) or exclusively by trustworthy nodes For example, a node that has additional security measures (e.g. firewalls, access restrictions to the node or similar similar) to prevent manipulation of the knot. Alternatively or additionally, for example, when a new data block is chained to the distributed database system, a trustworthy node can store a node checksum (e.g. a digital signature or a certificate) in the new data block. In particular, a proof can be provided that indicates that the corresponding data block was inserted by a certain node or indicates its origin. The devices (e.g. the corresponding device) are are, for example, devices of a technical system and / or industrial plant and / or an automation network and / or a manufacturing plant, which are in particular also a node of the distributed database system. The devices can, for example, be field devices or devices in the Internet of Things, which in particular are also a node of the distributed database system. For example, nodes can also include at least one processor in order to, for. B. to execute their computer-implemented functionality.

In the context of the invention, a “block chain oracle” and the like can be understood to mean, for example, nodes, devices or computers which are considered to be reliable data. The data obtained from nodes known as a “block chain oracle” are, for example, correct or not viewed as manipulated because such nodes have a security module that has, for example, software protection mechanisms (e.g. cryptographic procedures), mechanical protection devices (e.g. a lockable housing) or electrical protection devices (e.g. Tamper protection or a protection system that deletes the data of the security module in the event of improper use / treatment of the block chain oracle. The security module can, for example, include cryptographic keys that are used to calculate the checksums (e.g. transaction checksums or Node checksums) are necessary.

In the context of the invention, a “computer” or a “device” can include, for example, a computer (system), a client, a smart phone, a device or a server, each of which is arranged outside the block chain or is not a participant in the distributed database system (e.g. the block chain) (i.e. do not perform any operations with the distributed database system or only query them without carrying out transactions, inserting data blocks or calculating proof-of-work evidence). Alternatively, in particular, a computer can also be understood to mean a node of the distributed database system. With others In particular, a device can be understood to mean a node of the distributed database system or a device outside the block chain or the distributed database system. A device outside the distributed database system can, for example, access the data (e.g. transactions or tax transactions) of the distributed database system and / or from nodes (e.g. by means of

Smart contracts and / or blockchain oracles) who controlled. If, for example, a control or control of a device (for example a device designed as a node or a device outside the distributed database system) is implemented by a node, this can be done, for example. B. by means of a smart contract, which is stored in particular in a transaction of the distributed database system.

[1] Andreas M. Antonopoulos "Mastering Bitcoin: Unlocking Digital Cryptocurrencies", O'Reilly Media, December 2014

[2] Roger M. Needham, Michael D. Schroeder "Using encryption for authentication in large networks of Computers" ACM: Communications of the ACM. Volume 21, No. 12 December 1978,

[3] Ross Anderson "Security Engineering. A Guide to Building Dependable Distributed Systems" Wiley, 2001

[4] Henning Diedrich "Ethereum: Blockchains, Digital Assets, Smart Contracts, Decentralized Autonomous Organizations", CreateSpace Independent Publishing Platform, 2016

[5] "The Ethereum Book Proj ect / Mastering Ethereum"

https://github.com/ethereumbook/ethereumbook, as of October 5, 2017

[6] Leemon Baird "The Swirlds Hashgraph Consensus Algorithm: Fair, Fast, Byzantine Fault Tolerance", Swirlds Tech Report SWIRLDS-TR-2016-01, May 31, 2016

[7] Leemon Baird "OverView of Swirlds Hashgraph", May 31, 2016 [8] Oracle's blockchain https: // blockchainhub. net / blockchain oracles /

The embodiments and features described for the proposed distributed database system apply accordingly to the proposed method for operating a distributed database system.

Further advantageous embodiments and aspects of the inven tion are the subject of the dependent claims and the embodiments of the invention described below. In Wei teren the invention is explained in more detail by means of embodiments with reference to the accompanying figures.

Fig. 1 shows a schematic representation of an embodiment of an industrial automation network with a distributed database system;

Fig. 2 schematically shows an embodiment of a block chain;

Fig. 3 shows a flow diagram for a method for operating a block chain; and

Fig. 4 shows schematically another embodiment of a block chain.

In the figures, elements that are the same or have the same function have been provided with the same reference symbols, unless stated otherwise. 1 shows a schematic representation of an embodiment of an industrial automation network in which a distributed database system is used. 1 shows a distributed database system in the manner of a block chain 1, which is illustrated in FIG. 2 in more detail. The distributed database system 1 here comprises networked node devices 2-6.

The node devices are coupled to a network 7 and can in principle exchange data with one another. Knot devices 2 - 6 include, for example, computers with blockchain clients or field devices and mobile end devices. In the illustrated embodiment, for example, sensor data from field devices 11, 12,

13 of an industrial automation network 10 generated who are saved. Saving takes place in the form of transactions between participants. For example, a transaction for a subscriber, for example a sensor device 11, can consist in documenting or storing a sensor value. In the following, “subscriber” is understood to mean any entity for which an assigned information is entered within the distributed database system 1. Similarly, information can be stored by a transaction within the block chain BC.

In Fig. 1, a general subscriber 8 is Darge on the left. In order to carry out transactions within a block chain BC, the participants 8 must use block chains

identification data can be identified, e.g. B. be a network address. Public keys of a key and lock pair are often also used as block chain identification dates. This is indicated in FIG. 1 with a private key SK and a public key PUB for the subscriber 8. The keys SK, PUB are linked to one another via a cryptographic process and serve to cryptographically secure transactions in the block chain BC. Transactions between participants or changes to database entries caused by the data blocks explained in the following are protected by a cryptographic security procedure in the manner of signed data blocks.

A block chain BC is indicated schematically in FIG. 2. In a block chain BC, data blocks Bi are generated one after the other, the successive data blocks, which are designated in FIG. 1 Bi, Bi + 1 and Bi-1, being cryptographically linked to one another. For example, the data block Bi + 1 which is the most recent in time in FIG. 2 and which, like the other previous data blocks Bi and Bi-1, comprises header data HD, hashed data block data BH and transaction data TD, is linked to the previous data block Bi. by writing a hash value of the previous data block Bi. This is marked in FIG. 2 by the curved arrows with the addition "hash". All data - in particular the transaction history of the block chain BC - are included in the hash value formation of the previous data block, so that undetected manipulation of data, in particular transaction data, is very unlikely.

When creating a new data block that is intended to document requested transactions between participants, the node devices 2 - 6 check that the computer capacity is available to determine whether the pending transactions contradict the previous transaction history or not. For example, a transaction is confirmed if the majority of the node devices classify the transaction as being free of contradictions with regard to the transaction history.

It is therefore cryptographically secured chaining, with a cryptographic signature process being used for every transaction. In conventional block chains, a specific cryptographic method is selected at the start of the block chain and used for the life of the block chain. In the proposed method for operating the distributed database 1, the signature method used for the protection can be flexibly defined for each transaction, for example by specifying a complete parameter set that uniquely characterizes the signature method to be used, in particular the respective key length. A link to such parameter data that identifies the cryptographic signature method or to executable program code that implements the signature calculation is also conceivable. As a result, the cryptographic security level of the block chain can also be adapted to the current requirements. This is indicated schematically in FIG. 3, which in an operating method for the distributed database system according to FIG. 1 represents method steps taking place in the manner of a block chain according to FIG. 2.

In step S1, a transaction request is generated by a participant 8. For example, a credit for an amount of a cryptocurrency is to be made for a specific network address which is assigned to the respective subscriber 8. The transaction request must be signed using a cryptographic key and an associated cryptographic signature method.

When the distributed database system 1 is operated, the cryptographic signature method to be used is defined for each transaction (step S2). For less security-relevant transactions, for example, an ECDSA procedure with a 160-bit module can be used to save computing power. For transactions that are currently relevant, an ECDSA procedure with a 256-bit module is used, for example. If a 256-bit module no longer appears to be sufficiently secure in the future, a 320-bit module will be defined for transactions in database system 1.

Each transaction request, or an execution request for the transaction, contains signature information to determine the cryptographic signature method. The signature Information identifies the signature method to be used, for example by specifying a key length. The signed transaction request is then checked with the aid of a public key in accordance with the defined key length and the associated procedure, eg ECDSA.

When the block chain BC is operated by the distributed database system 1, the network address of the subscriber can be digitally signed as a block chain identification date together with the requested transaction. For example, the certification authority 9 (cf. FIG. 1) generates a pair of a public verification key PUB and a private cryptographic key SK as digital signature keys in accordance with the specified cryptographic signature method Assigned to 8 participants.

In step S3, the transaction request is provided or signed with the signature using the defined cryptographic signature method, which is identified by the signature information. The execution of the signing process can be implemented in the manner of a smart contract as executable program code, the signature information representing, for example, a pointer or pointer to the code.

Subsequently, transactions are carried out in step S4 on the basis of the signed transaction data. A new data block is created using the specified cryptographic procedure. Due to the transaction-dependent definition of the signature information or the cryptographic signature method, the block chain BC can have data blocks with different digital signatures.

This is indicated in FIG. 4. Blocks Bi-1 to Bi + 2 have been generated over time t. At time t *, the cryptographic signature procedure used was changed. Up to block Bi, the cryptographic security of the transactions was guaranteed using a signature SIG1.

For example, since the computing power available for cryptanalysis has increased over time t and the respective cryptographic signature procedure for SIG1 was no longer considered to be sufficiently secure, the signature procedure for the transactions after time t * has been changed. The subsequent blocks Bi + 1, Bi + 2 contain signatures SIG2, which have a stronger cryptographic security level than the signature process for SIG1. The participants in the block chain BC have agreed, for example by majority vote, to use a longer key length than before from time t *.

The flexible determination or determination of the signature process can ensure that a for the

Transaction adequate security level is reached. In this respect, the proposed method for operating a block chain, in which transactions are carried out using digitally signed transaction data, is suitable for building security-relevant databases. This can affect sensor and control data of an automation network, for example. It is also conceivable to use it as a digital land register or to prove certain safety properties of products. Because the cryptographic link to the participant, for example a real or legal person, can be flexibly adapted, a permanently secure operation can be achieved.

In the proposed method for operating distributed database systems, the aforementioned aspects with regard to block chains, such as smart contracts, checksums and the like, are taken into account in particular. Although the invention was explained using a simple block chain, the previously described variants of distributed ledgers can also be operated with other variants of distributed databases. Overall, the security and reliability of transactions between participants are improved as a result flexible adaptation of the cryptographic security level is made possible.

5

Claims

1. A method for operating a distributed database system (1) with distributed node devices (2-6) for providing linked data blocks (Bi), in particular in the manner of a block chain (BC), which transactions between participants (8 ) document, whereby transactions (TD) between participants (8) are secured with the help of transaction data and a cryptographic signature procedure, with the steps:

for each transaction, defining the cryptographic signature method (S2) for securing the respective transaction, wherein signature information identifying the specified cryptographic signature method is part of the transaction or part of an execution request for the transaction;

for each transaction, calculating signature data according to the specified cryptographic signature procedure for at least part of the transaction data or its hash value; and

Add the signature data to the transaction data.

2. The method according to claim 1, wherein the signature information comprises a program code for performing the specified cryptographic signature method.

3. The method according to claim 1 or 2, wherein the signature information has a pointer to a program code for performing the specified cryptographic signature method.

4. The method according to any one of claims 1-3, further comprising

send:

digitally signing the signature information using the specified cryptographic signature method; and

Append the signed signature information to the transaction data.

5. The method according to any one of claims 1-3, further comprising:

Generating a hash value for the signature information; and

digitally signing the hash value using the defined cryptographic signature procedure; and

Append the signed and hashed signature information to the transaction data.

6. The method according to any one of claims 1-5, wherein in a change transaction for all subsequent transactions (Bi + 1, Bi + 2), a new cryptographic signature method for securing the respective transaction is determined if a predetermined proportion of participants (8) one Approves the change transaction using the currently defined cryptographic signature process.

7. The method according to any one of claims 1-6, wherein a predefinable cryptographic signature method in the manner of a smart contract (SC) for or in the distributed database system (1) is provided.

8. The method according to any one of claims 1-7, wherein the interlinked data blocks (Bi), which document transactions between participants (8), comprise data blocks which are secured with the aid of different cryptographic signature methods (SIG1, SIG2).

9. The method according to any one of claims 1-8, wherein the cryptographic signature method a cryptographic key pair sel (SK, PUB) cryptographically linked and each participant (8) is assigned a current key pair (SK, PUB).

10. The method according to any one of claims 1-9, wherein the cryptographic signature method is implemented on the basis of post-quantum cryptography (PQC).

11. The method according to any one of claims 1-10, wherein the following steps are carried out for each participant (8):

Assigning a digital signature key (SK) to the subscriber (8), the digital signature key (SK) corresponding to the currently defined cryptographic signature method;

digitally signing (S3) a transaction request from the subscriber (8) using the digital signature key (SK) assigned to the subscriber (8) to generate a digitally signed transaction request; and

Confirming (S4) the transaction if the digital signature (SK) is recognized as valid and if the transaction with a transaction history of the block chain (BC) as a distributed database system (1) is free of contradictions.

12. The method according to any one of claims 1-11, wherein the linked data blocks (Bi) document transactions to a resource, in particular a cryptocurrency, and a security level of the cryptographic signature method depending on a value or an amount of the transaction documented resource.

13. The method according to any one of claims 1-12, wherein the linked data blocks (Bi) document transactions to a resource, in particular a cryptocurrency, and the transaction is carried out by checking the signature in the transaction data by auditors, and for verifying a lot of the managed resource is to be transferred to the verifying bodies, which depends on the computation effort of the signature verification.

14. Distributed database system (1) with a plurality of node devices (2-6) for providing linked data blocks (Bi), in particular in the manner of a block chain (BC), each node device (2-6) being set up is to document transactions between participants (8) in accordance with a predetermined block chain algorithm, where the block chain algorithm is used to carry out a process rens according to one of claims 1-13 by the node devices (2-6).

15. Industrial automation network (10) with a distributed database system (1) according to claim 14 for documenting and controlling transactions for field devices (11-13).