Method for securely removing blocks from an existing blockchain

Abstract

The present invention relates to a method for securely removing blocks from an existing blockchain in a closed infrastructure such as a corporate network. The proposed method provides the advantage that entries can be removed from the linked list without jeopardising the continued integrity of the chain. In principle, blockchains do not permit blocks to be removed from the data structure; this is prevented by redundant storage. The present invention overcomes this disadvantage and additionally provides a mechanism that allows the data records to be restored at a later time, if required. The invention is also directed to a correspondingly configured system arrangement. The invention also relates to a computer program product comprising control commands which implement the proposed method and / or operate the proposed apparatus and arrangement.

Description

[0001]Method for Securely Removing Blocks from an Existing Blockchain The present invention relates to a method for securely removing blocks from an existing blockchain in a closed infrastructure, such as a company network. The proposed method offers the advantage that entries can be removed from the linked list without compromising the overall integrity of the chain. Blockchains generally do not allow blocks to be removed from the data structure, as this is prevented by redundant storage. The present invention overcomes this limitation and also provides a mechanism that allows the data records to be subsequently restored if necessary. The invention further relates to a correspondingly configured system arrangement. A computer program product with control commands is also proposed, which implements the proposed method.The proposed device and arrangement are to be operated. The present invention relates to blockchain technology, in particular methods and systems for the subsequent deletion of blocks within a blockchain. This is an emergency technology that makes it possible to irretrievably destroy encrypted files. The present invention provides a method and a system that makes it possible to subsequently delete blocks in a blockchain without jeopardizing the integrity of the remaining blockchain. This is achieved by introducing a special, erasable block structure and a deletion protocol. A blockchain is generally known. A blockchain can be described as a special form of linked list in which each block in the chain contains not only the data but also a hash value of the previous block. This hash acts as a pointer that uniquely links each block to its predecessor. The chainingThis is achieved through cryptographic hashes based on the block contents. If the content of a block changes, its hash also changes, which in turn invalidates the hash of the next block. This structure makes the blockchain particularly resistant to manipulation, as any change in a block would affect the entire chain. State-of-the-art blockchain technology is known for its immutability, meaning that once data is added to the blockchain, it cannot be deleted or altered. This property is crucial for data integrity and security. However, there are use cases where the ability to subsequently delete specific blocks would be advantageous, for example, to meet technical requirements, correct erroneously entered data, or delete data that has fallen into the hands of criminals during an attack. The current state of the art...Cloud encryption technology encompasses various approaches and technologies that work together to protect data both at rest and in transit. Here are some key aspects: End-to-end encryption: Data should be encrypted both during transmission and at rest. End-to-end encryption ensures that only authorized users can decrypt the data, even when it is stored in the cloud or transferred between cloud services. Strong encryption algorithms: Modern cloud systems use strong encryption algorithms such as AES (Advanced Encryption Standard) with long key lengths (e.g., 256 bits). These algorithms offer a high level of security and resilience against attacks. Key management: Effective key management is crucial to ensuring the secure exchange of encryption keys. This includes the secureKey generation, storage, rotation, and deletion. Various techniques such as Key Management as a Service (KMaaS) or Hardware Security Modules (HSMs) can be used to securely manage keys. Multi-factor authentication (MFA): In addition to encryption, authentication is a crucial aspect of security. MFA requires more than just a password to authenticate a user, significantly improving security. Data Loss Prevention (DLP): This is a set of technologies and processes that ensure sensitive data does not enter or leave the cloud without authorization. Zero-knowledge proof techniques: These techniques allow a service provider to process data without knowing its content. For example, zero-knowledge proof techniques can be used to perform searches in encrypted databases without revealing the data itself. Homomorphic encryption: This isAn advanced technique that allows operations to be performed directly on encrypted data without decrypting it. This enables calculations to be carried out in the cloud while maintaining data privacy. However, current state-of-the-art methods for securing data in the cloud also present significant disadvantages and problems: Key management: Effective key management is crucial but also difficult. The secure generation, storage, rotation, and deletion of keys require special attention. Losing encryption keys can lead to permanent data loss, while unauthorized key acquisition can render the entire encryption effort useless. This has already happened multiple times with major providers. Complexity: Implementing and managing encryption systems in the cloud can be complex and often requires...Specialized knowledge and resources. Companies need to familiarize themselves with various technologies, standards, and best practices to ensure adequate security. Access control and data analysis: While encryption improves data protection, it can also impair the ability to analyze and process data. Accessing encrypted data for analysis or processing requires specialized techniques such as homomorphic encryption or zero-knowledge proof, which can introduce additional complexity. Regulatory requirements: Compliance with data protection and compliance regulations can be challenging, especially when data is stored and processed in the cloud. Many regulatory bodies have specific requirements for the encryption of sensitive data that must be considered. Trust in the cloud provider: Although cloud providers often offer encryption as a service,Customers must trust that the provider has implemented appropriate security measures and adequately protects the data. This requires a careful review of the provider's security policies, contracts, and compliance certifications. Cloud providers such as Microsoft, AWS, etc., are also constantly exposed to attacks aimed at gaining access to the data stored there. This has happened repeatedly in the past and will continue to happen in the future. Therefore, it is a task to propose a method for the secure removal of blocks from an existing blockchain within a closed infrastructure, which overcomes the aforementioned disadvantages. Furthermore, it is a task of the present invention to propose a correspondingly configured system arrangement. Finally, it is a task to provide a computer program product with control commands that implement the method or the proposed system.The present invention aims to operate the device and arrangement. Furthermore, it is an object of the present invention to provide a suitably configured device. Additionally, a computer program product is to be provided which contains control commands that implement the method or operate the proposed device. This object is achieved by a method with the features according to claim 1. Further advantageous embodiments are specified in the dependent claims. Accordingly, a method for securely removing blocks from an existing blockchain in a closed infrastructure is proposed, comprising: providing a conventional blockchain comprising blocks and references that form a linked list and where each block has at least one parameter; operating the conventional blockchain in a self-contained, network-based infrastructure comprising network nodes, wherein theThe conventional blockchain is redundantly distributed across at least a subset of network nodes; a network node creates a deletion request for at least one block of the conventional blockchain, which is then transmitted to other network nodes; if the deletion request is approved by the network nodes according to a approval metric, a separate blockchain is created, containing at least one block with a deletion entry, where each block of the separate blockchain contains a reference to a block of the conventional blockchain to be deleted, and the deletion request is executed according to the separate blockchain by the corresponding network nodes. In a further aspect, the process is designed such that the block to be deleted is encrypted with a strong symmetric encryption algorithm, such as AES-256-GCM, before being stored in the conventional blockchain. The algorithm used in this process...Cryptographic keys are distributed exclusively to authorized entities, preferably via asymmetric encryption, and stored within a secure key management system within the closed infrastructure. To delete a block, the block itself is not removed from the blockchain; instead, the associated symmetric key is irretrievably deleted from all storage media, including volatile memory, non-volatile memory, and any existing backups. This makes it technically impossible to decrypt the ciphertext remaining in the blockchain. This approach has the advantage of achieving immediate, resource-efficient, and irreversible decryption of large amounts of data without requiring physical deletion operations on the block itself at all nodes. Furthermore, the integrity of the blockchain structure is preserved, as the encrypted block remains part of the blockchain.The linked list can remain intact while access to the original plaintext is computationally excluded. Furthermore, the deletion of the key can be logged in a separate deletion blockchain in an audit-proof manner, ensuring the traceability and auditability of the deletion process to third parties, particularly in the context of data protection requirements such as the GDPR. The proposed method describes an inventive way to securely remove data blocks from an existing blockchain within a closed, network-based infrastructure. This represents an innovative solution to a central problem in blockchain technology arising from the fundamental principle of immutability. Normally, data in a blockchain is designed to remain immutable once entered, thus guaranteeing the integrity and security of the blockchain. This methodHowever, it offers a way to selectively and controllably remove blocks from the blockchain without affecting its fundamental structure or trust. The following sections describe each feature of this method in detail, explaining its associated technical advantages and possible implementations. First, the method requires the deployment of a conventional blockchain. A blockchain consists of a linked list of blocks connected by cryptographic references. This linked structure means that each block contains a hash value of the previous block, ensuring the security and integrity of the blockchain, as any change to one block would affect subsequent blocks. Each block in this chain contains at least one parameter, which acts as a data or information unit. These parameters can vary depending on the use case, for example...Transaction data in cryptocurrencies or other valuable information in various blockchain applications, document management, or general file management. Using this structure guarantees that the data is stored consistently and securely in the blocks. The process operates within a closed, network-based infrastructure. This infrastructure consists of multiple network nodes that jointly manage and operate the blockchain. The term "closed" indicates that the system is isolated and network-locked, which is a crucial security measure. Since there are no external connections, the risk of cyberattacks or unauthorized external access is minimized. Within this infrastructure, the traditional blockchain is redundantly distributed across a subset of the network nodes. This redundancy means that multiple nodes maintain copies of the blockchain.This redundancy significantly increases the system's reliability. Even if one or more nodes fail, the blockchain remains functional and can be accessed from other nodes. This redundancy ensures high availability and stability, particularly in security-critical environments where continuous access to the blockchain is essential. The characteristic of a "closed, network-defined infrastructure" in this context refers, for example, to a company network that is completely isolated and self-contained. In such a network, administrators have full control over the management, configuration, and security of the entire infrastructure. This means they possess all necessary rights to monitor, control, and modify every network component. This allows them to modify the blockchain at their own discretion. "Closed" in this context means...The context does not imply that there is no network path to another network. Typically, corporate networks are connected to the internet, but are physically and software-isolated from it. An entry server or proxy is typically present, creating a closed infrastructure by isolating the corporate network from the internet. In detail, such a corporate network is usually completely isolated from external networks, especially the internet, to maximize data security. Administrators control network access and enforce security policies to ensure that only authorized users and devices can access the network. This not only prevents unwanted external access but also enables comprehensive monitoring and control of all internal processes. Within this closed environment, administrators ensure that all data, including the data contained in theBlockchain blocks are protected from external threats. Administrators are able to configure and secure network resources such as servers, firewalls, switches, and routers. This complete administrative control allows the network to be adapted to the company's operational requirements while ensuring the highest level of data security. Administrators also have full decision-making power over the distribution and management of the blockchain running on this network. They can determine which network nodes have access to the blockchain and how it is distributed. Blockchain redundancy, meaning that copies of the blockchain are stored on different nodes in the network, is also managed by the administrators. This ensures that even in the event of a failure of individual nodes, the blockchain remains accessible and functional.This typically occurs through the underlying infrastructure without human intervention. Additionally, administrators can implement security protocols that precisely monitor who has access to which data and what changes are made. In the case of deletion requests or other security-critical actions, as described in the proposed procedure, it is the administrators' responsibility to monitor these processes and ensure they comply with the company's predefined policies and security requirements. The administrators' complete control over the network thus guarantees that the secure block removal process takes place in a highly secure, monitored environment where all activities are documented and traceable. Furthermore, administrator privileges allow the blockchain to be edited, which is not currently possible. Another feature of the procedure is...The ability to delete blocks from the blockchain, which is not normally provided for in conventional blockchains. This process is initiated by a deletion request created by one of the network nodes. A deletion request can be understood as a formal request to remove specific blocks from the blockchain. This request specifies the block(s) to be deleted and is then transmitted to the other network nodes within the network. This is an element of the decentralized nature of the system, as the decision to delete is not made by a single node but by the entire network architecture. Distributing the deletion request across multiple nodes ensures that no central authority has complete control over the deletion process. This increases transparency and trust in the process. To decide whether the deletion request should be approved,A so-called approval metric is applied. This metric defines which criteria and rules must be met for a deletion request to be approved by the network nodes. For example, the metric might stipulate that a certain number of nodes must agree to the deletion before it can be carried out. The exact nature of the approval metric can vary depending on the use case; it could be based on majority decisions, specific security checks, or other conditions. This metric is a key mechanism to ensure that the deletion process is not arbitrary or uncontrolled, but rather follows clearly defined rules and is in accordance with the system's specifications. One advantage of the approval metric is that it brings transparency and traceability to the decision-making process, thus preserving the integrity of the network. After the deletion request has been approved, that is,After the network nodes agreed to the deletion according to the notification metric, a further step was taken: the creation of a separate blockchain. This new blockchain serves the purpose of documenting and tracking the deletion processes. Each block in this separate blockchain contains at least one so-called deletion entry. This entry refers to a block in the original, traditional blockchain that is to be deleted. This link between the separate blockchain and the traditional blockchain is important because it enables complete and transparent documentation of the deletion process. The separate blockchain thus functions as a kind of "logbook" or record that documents all deletion processes. This clear separation between the traditional blockchain and the separate blockchain ensures that the integrity and immutability of the original blockchain are preserved, while still allowing for the necessary data to be tracked.Specific blocks can be securely and transparently deleted. The actual deletion of the blocks is then carried out by the network nodes that operate the traditional blockchain. These nodes execute the deletion request based on the separate blockchain by removing the corresponding blocks from the traditional blockchain. This process ensures that the deletion is decentralized and synchronous across all affected nodes. The network nodes work together in a coordinated manner to ensure that the blockchain remains consistent across all nodes, even when blocks are removed. This step is crucial to ensuring that the system's redundancy and availability are maintained even after blocks are deleted. The technical advantage of this method lies in the ability to securely and transparently delete data in a blockchain without compromising the fundamental principles of blockchain.In particular, it prevents the immutability and integrity of the data from being compromised. Creating a separate blockchain to document deletion processes ensures that all deletions are precisely traceable and verifiable, which is crucial in many environments. Furthermore, the consensus mechanism between network nodes provides additional security by preventing unauthorized or uncontrolled deletions. Overall, this method offers a technically sophisticated solution to the problematic issue of data deletion in immutable blockchain systems. It enables flexible data management and deletion processes without jeopardizing the fundamental security and consistency of the blockchain. This method is particularly advantageous in applications that store sensitive data, as it allows for the secure deletion of specific information while simultaneously maintaining the integrity of the blockchain.Transparency and traceability of the process remain guaranteed. The solution according to the invention comprises the securing of cloud systems through the implementation of a blockchain infrastructure that enables transparent, secure, and decentralized management of encryption keys. This solution utilizes the inherent security and immutability of blockchain technology to significantly improve key management, ensure data integrity, and guarantee trust between exchanging participants within the platform. By combining cryptographic methods and smart contracts, our solution enables the secure exchange of encryption keys, secure data storage and transmission, and transparent verification of access rights and activities in the cloud. Furthermore, the blockchain infrastructure enables seamless integration with existing cloud platforms andIt offers a scalable solution for companies of various sizes and industries. The development goal was to ensure seamless integration into existing infrastructures without forcing users to adopt a completely new environment. Therefore, this is an add-on that complements existing, even organically grown, IT structures without requiring users to abandon familiar features. This ensures interoperability, consistency, and the existing user experience. Furthermore, management and maintenance are centralized. Future threats from AI are also addressed, as the software incorporates abnormal behavior detection at the node level, pattern recognition, and smart contract monitoring. Thanks to its technical capabilities, native integration with the Azure Marketplace and all associated automations are possible. For the user, our seamless software solution translates into, for example, lower total cost of ownership, as fewer resources are required forImplementation, integration, training, and support, or even a complete migration to a new environment, are often required. For the first time, it's possible not only to link existing cloud infrastructures with blockchain applications / use cases (e.g., DMS, supply chain, messenger, etc.), but also to integrate them directly and natively into existing environments and use them as an additional layer of data security in the background. It's irrelevant how and for what purpose the underlying system is used, or whether there are already other encryption components. No additional external service providers with their own cloud infrastructure or similar are needed to provide these functions. Our solution can be used both off-premises and on-premises. On the user side, a client is required that contains the private chain, which communicates with the main chain (cloud / server). The client integrates as a service into the Windows system.Users monitor, for example, the (business) OneDrive folder. A virtual file system ensures that no file fragments remain directly in Windows, thus preventing data theft. This virtual file system uses sandboxing and isolation mechanisms to prevent the execution of potentially malicious code. This helps to ensure the system's security against malware and other threats. Files are encrypted with a new key on a rolling basis as soon as the processing is complete. This means that Windows processes have no access to the encrypted files within the virtual file system and cannot be intercepted or read by third parties. It is also possible to destroy existing keys, thus completely preventing access to the data. Azure (cloud) additionally creates snapshots of the modified data within the blockchain, enabling versioning.This enables not only the detection of data changes but also the identification of what exactly has been changed. No other product on the market currently offers these capabilities, nor the native integration as a Microsoft app in the Microsoft Marketplace. The technical advantages of this architecture lie primarily in the immutability and security of the data. Cryptographic chaining makes any manipulation immediately apparent, ensuring a high level of integrity for the stored information. Furthermore, decentralization allows the blockchain to be stored and updated simultaneously on many nodes, making it particularly resilient and eliminating a central control point vulnerable to attack. Transparency and traceability are further significant advantages, as every transaction and every block is publicly verifiable, which is especially important in areas such as financial transactions.or is of great benefit to supply chains. Consensus mechanisms such as Proof of Work or Proof of Stake ensure that only valid blocks are added to the blockchain, thus creating additional security and trust in the system. The term blockchain is used here synonymously with the term linked list. The term can also be translated as block chain. After the deletion of data blocks or entries in the blockchain, the changes can be propagated in the network such that the adapted blockchain is again redundantly available in the desired version and consistent on the network nodes. According to one aspect of the present invention, after the deletion request is executed, blocks following the blocks to be deleted are adapted. This has the advantage that the structure and chaining of the blockchain are preserved even if individual blocks are deleted. In a blockchain, each block is cryptographically linked.Hashes are linked to its predecessor and successor. Deleting a block could theoretically break the chain and compromise the integrity of the entire blockchain. Adjusting subsequent blocks prevents this break, as all references pointing to the deleted block are modified accordingly. This keeps the chain consistent and allows subsequent blocks to continue to be referenced correctly. This ensures the functionality of the blockchain by maintaining all cryptographic connections and dependencies after a block is deleted. According to another aspect of the present invention, after the deletion request is executed, blocks following the blocks to be deleted are adjusted with respect to their stored references, checksums, hash values, consistency information, and / or integrity information. This has the advantage of ensuring the security of the blockchain.The cryptographic layer remains completely intact. Checksums, hash values, and other consistency information are essential to ensure the immutability of the blockchain. If a block is deleted, this information could become invalid in subsequent blocks because it refers to the previous block. By adjusting these cryptographic parameters, the consistency of the blockchain is maintained, and any manipulation is immediately detected. This prevents the deletion process from creating security vulnerabilities and ensures that the entire blockchain remains reliable and unchanged. This is particularly important in security-critical areas such as financial transactions or sensitive data storage systems. According to another aspect of the present invention, blocks to be deleted are stored in a different blockchain than the conventional blockchain and / or an archive. This has the advantage that deleted blocks are stored in a different blockchain than the conventional blockchain.Data is not irretrievably lost but can be securely stored in another blockchain or archive. This makes it possible to restore or verify deleted blocks at a later time if necessary. This is particularly advantageous in regulatory or legal contexts, as it allows companies to remove data from the active blockchain while simultaneously preserving it securely for availability in the event of audits or legal disputes. This creates a balance between deleting data from the blockchain and maintaining the traceability of historical transactions. According to another aspect of the present invention, the decision metric corresponds to a majority vote or a predetermined approval threshold. This has the advantage that decisions regarding the deletion of blocks are not made centrally but democratically by the network.Majority voting or a defined approval threshold prevents individual network nodes from having sole control over deletions. This consensus mechanism increases trust in the blockchain system because multiple nodes are involved in the decision-making process, preventing unauthorized deletions. The advantage of this metric is that the entire network plays a role in ensuring data integrity, which is particularly important in decentralized and distributed systems like blockchain. According to another aspect of the present invention, the decision metric is evaluated based on a validity check, an authenticity check, and / or existing blocks. This has the advantage that the decision on deletion requests is not based solely on majority voting but must also undergo technical checks to validate and authenticate the requests. A validity check ensures that theThe request is legitimate and meets the technical requirements, while an authenticity check verifies the source of the request. This minimizes the risk of unauthorized deletion requests being approved. The additional review of existing blocks ensures that the deletion process has no unintended consequences for the rest of the blockchain. These multi-stage checks strengthen the security and integrity of the entire deletion process. According to another aspect of the present invention, the deletion request is executed by deleting at least one block, removing the reference to the block, overwriting the block, discarding decryption information, deleting at least one parameter of the block, modifying a hash value, and / or encrypting the block. This has the advantage of providing various options for performing the deletion, depending on the specific requirements.Security and data protection requirements can be adapted. The ability to overwrite a block or discard its decryption information ensures that the data can be irretrievably removed without any possibility of retrieving the deleted information. Furthermore, changing the hash value or removing the references ensures that the block is no longer anchored in the blockchain. This flexibility allows deletions to be carried out in a way that meets specific data protection and data security requirements. According to another aspect of the present invention, the deletion request includes at least one deletion reason and / or a recovery attempt is made depending on this deletion reason. This has the advantage of making the deletion process better documented and more traceable. By assigning a specific reason to each deletion request, theAdministrators or node operators can better understand and monitor the deletion process. Should an accidental or unlawful deletion occur, the documented reason for deletion provides the basis for restoring the data if necessary. This feature creates additional security and flexibility in handling sensitive data, as it enables recovery in case of an error. According to another aspect of the present invention, the conventional blockchain is imported into the closed infrastructure via an interface. This has the advantage that existing blockchain data can be securely imported into a closed infrastructure, such as a corporate network. This interface ensures that all data is transferred securely and efficiently without compromising the integrity of the blockchain. The closed infrastructure also offers protection against external threats by storing the blockchain data in a secure environment.processed in a controlled and isolated network environment. This is particularly useful when blockchains from open networks need to be imported into security-critical environments, such as companies or government agencies with high security requirements. According to another aspect of the present invention, the blocks of the conventional blockchain each refer to a document, which is locked for editing when a corresponding deletion request is made. This has the advantage that no parallel changes can be made to the linked documents during the deletion process. This prevents inconsistencies between the blockchain entries and the referenced documents, as these remain locked during processing. Locking the documents ensures that the data remains coherent and consistent while the deletion process is being carried out. This contributes to data security and ensures that no conflicts arise between theBlockchain transactions and the linked documents are created. According to another aspect of the present invention, the closed network infrastructure is technically separated from any other connected network. This has the advantage that the blockchain operates in a completely isolated network, which is protected from external influences and threats. This isolation ensures that no external networks have access to the blockchain data and that the company network remains protected from cyberattacks or unauthorized access. This significantly increases the security of the blockchain data, especially in environments with high security requirements, such as financial institutions or government agencies. According to another aspect of the present invention, the network nodes are distributed throughout the infrastructure as hardware and / or software components. This has the advantage that theBlockchain networks can be flexibly designed and adapted to the needs of the company. Hardware-based nodes offer physical security and enable better control over the infrastructure, while software-based nodes offer faster scaling and easier management. The combination of hardware and software components increases the network's resilience and redundancy, as software nodes can take over if a hardware node fails, and vice versa. This distribution increases the system's availability and reliability and allows for adaptation to various operational requirements. Furthermore, the process includes a crypto-shredding mechanism where, to delete a data block, not the data block itself, but the associated symmetric encryption key is irreversibly destroyed. The data block can then remain in the blockchain or in an external repository.The data remains in the closed storage system, but is permanently unreadable without the key. The key is previously stored in the separate deletion blockchain under an encrypted reference, ensuring its destruction is also documented in an audit-proof manner. This has the advantage of enabling the immediate and resource-efficient rendering of large amounts of data unreadable without requiring physical deletion processes on all nodes, and it eliminates the risk of residual data, as access is impossible without the key, even through forensic methods. Furthermore, the process is designed so that all data is encrypted client-side during creation or upload within the closed, network-based infrastructure, with the infrastructure operator never having access to the encryption keys used (zero-access principle). Deletion then occurs...This is also achieved by destroying the keys, which are stored exclusively within the customer domain or the operating administration area. A separate deletion blockchain documents both the request and the confirmation of key destruction. This has the advantage of ensuring GDPR-compliant data storage, where the operator has no technical means of accessing the content and deletion can be carried out securely, completely, and without any residual information at any time, even in complex distributed systems. Furthermore, the process operates within a permissioned blockchain, which is administered on a client-specific basis. Each client operates its own blockchain nodes within its closed infrastructure. The consensus mechanism is preferably a Byzantine Fault-Tolerant (PBFT) algorithm, enabling fast and trustworthy agreement between the nodes.The separate deletion blockchain can be managed on a client-specific basis, ensuring that deletion requests and confirmations are processed exclusively within the respective client's sphere of influence. This guarantees maximum data sovereignty, reduces the attack surface for external actors, and enables rapid consensus building without the latency of public blockchains. Furthermore, the process is designed so that the original blockchain and the separate deletion blockchain contain only cryptographic metadata, specifically hash values, digital signatures, and timestamps. Personal or content data is never stored in the blockchains. The link to the actual data objects is established via internal references within the closed infrastructure. This ensures that the blockchain itself operates completely independently of any data protection-relevant content.This can be achieved by maintaining auditability and auditability while significantly simplifying the legal framework for operation, as no personal data is processed. In another aspect, the data is encrypted client-side using a symmetric key (e.g., AES-256-GCM). This key is asymmetrically encrypted (e.g., RSA-4096 or ECC) separately for each authorized recipient and stored within the closed infrastructure. When data is deleted according to the inventive method, the corresponding key is destroyed, and this process is documented in the separate deletion blockchain as a transaction with a hash value, timestamp, and digital signature. This has the advantage of combining the high level of security of client encryption with tamper-proof documentation of the deletion process, which is useful for both security audits and regulatory compliance.In the context of this application, a "crypto-shredding mechanism" refers to a method for permanently rendering encrypted data unreadable. This method involves not physically removing or overwriting the encrypted data itself, but rather irreversibly destroying the cryptographic key required for decryption. The encrypted data block may remain in a storage system, particularly a blockchain or an associated, closed storage area, but due to the unavailability of the corresponding key, it is no longer computationally reconstructible into its original plaintext. The crypto-shredding mechanism can be designed, in particular, to document the key destruction in a tamper-proof manner in a separate blockchain to ensure the traceability and auditability of the deletion process.In the context of this application, "zero-knowledge deletion" refers to a method for permanently rendering encrypted data unreadable. In this method, all data is encrypted client-side before or during storage within a closed, network-based infrastructure, and the infrastructure operator never possesses the cryptographic keys required for decryption (zero-access principle). Deletion is achieved by irreversibly destroying these keys, which are held exclusively by the data owner or within a controlled administrative domain. Due to the lack of key availability, even the operator cannot computationally reconstruct the original plaintext. The implementation of zero-knowledge deletion can be designed, in particular, to ensure that the deletion process, including the destruction of the keys, is audit-proof.A separate blockchain is used to document data processing in order to ensure verifiable and auditable compliance with data protection deletion obligations, particularly under the GDPR. Client-side encryption refers to an encryption method in which data is encrypted exclusively on the client side, i.e., on the data owner's device, before being transmitted to a storage system or blockchain. The operator of the storage system receives only the encrypted data block and is never in possession of the unencrypted data or the associated keys, thus technically preventing the operator from gaining access to the plaintext. Permissioned blockchain describes a blockchain architecture in which participation in the network and the execution of transactions are restricted to a defined group of authorized nodes. Access to the blockchain, especially to write and management functions, is controlled via a centralor decentralized authorization management, which enables targeted control of participants, a defined governance structure, and a reduction in the attack surface compared to public blockchains. Byzantine Fault Tolerance, particularly in the form of Practical Byzantine Fault Tolerance (PBFT), refers to a consensus mechanism for distributed systems designed to make correct decisions even in the event of faulty or malicious behavior by individual nodes. PBFT represents a practical implementation used in permissioned blockchain environments to achieve trusted consensus with low latency and high throughput. Zero-Access Architecture describes a system architecture in which the operator never has access to unencrypted data or its decryption keys, as all data is encrypted under the control of the data owner, and the operator onlyIt functions as a passive transport or storage mechanism for encrypted data. An immutable ledger refers to a blockchain data structure in which data, once stored, cannot be altered or deleted without documented and authorized changes. Each change is stored as a new entry linked to the existing history, creating a complete and tamper-proof record of all transactions. Finally, an audit trail refers to a complete, tamper-proof logging of all relevant events and transactions within a system, especially a blockchain, enabling retrospective verification of processes, decisions, or deletions. This task is also accomplished by a system arrangement for the secure removal of blocks from an existing blockchain within a closed infrastructure, featuring an interface unit established to provide a conventionalA blockchain comprising blocks and references forming a linked list, with each block containing at least one parameter; an infrastructure established for operating the conventional blockchain within a self-contained, network-based infrastructure comprising network nodes, wherein the conventional blockchain is redundantly distributed across at least a subset of the network nodes; a request unit established for a network node to create a deletion request for at least one block of the conventional blockchain, which is transmitted to other network nodes; a blockchain unit established, upon a positive decision on the deletion request by the network nodes according to a decision metric, to create a separate blockchain comprising at least one block with a deletion entry, wherein each block of the separate blockchain contains a reference to one block of the conventional blockchain to be deleted.The invention features a deletion unit set up for executing the deletion request according to the separate blockchain by the corresponding network nodes. The problem is also solved by a computer program product with control commands that implement the proposed method or operate the proposed device. According to the invention, it is particularly advantageous that the method can be used to operate the proposed devices and units. Furthermore, the proposed devices and equipment are suitable for carrying out the method according to the invention. Thus, each device implements structural features that are suitable for carrying out the corresponding method. However, the structural features can also be designed as method steps. The proposed method also provides steps for implementing the function of the structural features. In addition, physical components can be similarly implemented.can also be provided virtually or in a virtualized form. Further advantages, features, and details of the invention will become apparent from the following description, in which aspects of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination. Likewise, the features mentioned above and those further described here can be used individually or in any combination. Functionally similar or identical parts or components are sometimes provided with the same reference numerals. The terms "left," "right," "top," and "bottom" used in the description of the exemplary embodiments refer to the drawings in an orientation with normally legible figure labels or reference numerals. The embodiments shown and described are not intended to be considered asThe figures are not intended to be a complete and definitive representation of the invention, but rather serve as examples to illustrate it. The detailed description is for the information of those skilled in the art; therefore, known circuits, structures, and methods are not shown or explained in detail in order to avoid complicating the understanding of the present description. The figures show: Figure 1: a schematic flowchart of the proposed method for securely removing blocks from an existing blockchain according to one aspect of the present invention; Figure 2: another schematic flowchart of the proposed method for securely removing blocks from an existing blockchain according to another aspect of the present invention; Figure 3: an exemplary linked list in which a block is to be deleted according to the proposed invention; Figure 4: an exemplary linked list in which a block is deleted according to the proposed invention andis archived; and Figure 5: an exemplary linked list in which blocks are deleted according to the proposed invention. Some of the present figures contain parameters which are familiar to those skilled in the art in their English designation and which are used as parameters and cannot be translated as such. Figure 1 shows in a schematic flowchart a method for securely removing blocks from an existing blockchain in a closed infrastructure, comprising: providing 100 a conventional blockchain comprising blocks and references which form a linked list and each block has at least one parameter; operating 101 the conventional blockchain in a self-contained network infrastructure comprising network nodes, wherein the conventional blockchain is redundantly distributed 102 across at least a subset of the network nodes; creating 103 a deletion request at leasta block of the conventional blockchain by a network node, which is transmitted to other network nodes 104; upon a positive decision 105 of the deletion request by the network nodes according to a decision metric, a separate blockchain is created 106, containing at least one block with a deletion entry, wherein each block of the separate blockchain contains a reference to a block of the conventional blockchain to be deleted, and the deletion request is executed 107 according to the separate blockchain by the corresponding network nodes. The block to be deleted is encrypted 108 before being stored in the conventional blockchain using a symmetric cryptographic key, the encrypted block is stored in the conventional blockchain, the associated key is kept exclusively in a key management facility within the closed infrastructure, and aSubsequent irretrievable deletion of the key from all storage media, including volatile memory, non-volatile memory, and backups, making it technically impossible to decrypt the stored block. Figure 2 shows a schematic flowchart of a method for securely removing blocks. The method according to the invention uses blockchain technology to regenerate encryption base data for each data transmission and to enable integrity verification at any time via the blockchain hash value. First, in step a), the sender requests a token from the encryption authority, which will be used as the basis for encrypting the data to be transmitted. In step b), the encryption authority creates the token and writes it to a new block created by the encryption authority, which is appended to its main chain.In step c), the encryption authority returns the created token to the sender. The sender then creates a key in step d), derived from the token and the last confirmed hash (or genesis hash). In step e), the sender S encrypts a message for transmission to the recipient E using the created key. The sender S then saves the hash of the unencrypted message in a new block of their private blockchain in step f) and transmits the encrypted message to the recipient E in step g). The sender creates the hash of the encrypted message in step h) and transmits it to the encryption authority. The recipient then transmits the hash of the encrypted message to the encryption authority in step i) and requests an integrity acknowledgment. The encryption authority then compares the hashes in step n).The process connects receiver E and sender S and transmits the comparison result and the token to receiver E. If the encryption authority confirms integrity, receiver E calculates the key for subsequent decryption of the message using an arbitrary encryption method in step o) from the token and the last confirmed hash of the unencrypted message (or genesis hash). If integrity is not confirmed, the process terminates at this point because the data between sender and receiver is inconsistent. In step p), receiver E decrypts the message using the key and, in step q), saves the hash of the unencrypted message in a block of its private chain. Finally, in step r), receiver E sends an acknowledgment of receipt for the hash of the unencrypted message to sender S and an acknowledgment of receipt of the hash of the encrypted message to the encryption authority.Further data transmissions. In addition, the following further steps are carried out, particularly between steps i) and n): k) the receiver bases the integrity request to the encryption authority on Transaction Tree (Merkle) technology, l) the encryption authority verifies the Transaction Tree using the main chain, m) the encryption authority transmits the result of the integrity check to the receiver. This Transaction Tree verification offers an extended check for integrity violations. Using the Merkle Tree Hashing method, it is possible to check the entire chain, i.e., the main chain as well as the private chains of the sender and receiver, for violations. Here, not only is the currently received message checked for changes using a hash value, but also the entire sequence of the chain. Integrity monitoring is thus improved, and the method offers a multitude of protection functions that are difficult to manipulate.Maintaining the integrity of a third-party system. Client operating procedure: First, the system identifies the data to be stored on the blockchain. This data could include, for example, transaction data, smart contract code, documents, or other relevant information to be recorded on the blockchain. The encrypted data is packaged into a transaction, which is then sent to the blockchain network. Smart contracts on the blockchain process the transaction of the encrypted data coming from the client (virtual file system). The smart contracts ensure that the data is stored and updated according to the defined rules and conditions. Storage in the virtual file system: The virtual file system (client) receives the encrypted data from the blockchain and stores it. When the user wants to access the stored data, the blockchain can send requests to the virtual file system.The file system is sent to retrieve the encrypted data. The data is then decrypted and returned to the user who has the necessary access rights. Throughout the entire process, security mechanisms are implemented to ensure the integrity and confidentiality of the data. This is achieved through access rights, MFA, and data encryption to ensure protection against unauthorized access. Figure 3 shows a blockchain with several blocks 1 to 5. The blocks have several parameters, such as Tx.1.1. References to subsequent blocks can also be stored here. In this case, the entry, or block, 3 is to be deleted. Some aspects of the present invention are explained below by way of example. 1. Deletable Block Structure The basis of the invention is the extension of the conventional blockchain structure by an additional data structure, which is referred to as a "deletion flag."The deletion flag is a Boolean value (true / false) that determines whether a block can potentially be deleted. The deletion flag is set to "false" by default but can be set to "true" during certain procedures, marking the block for deletion. Additionally, another field called "deletion reason" is introduced, which stores textual information indicating the reason for deleting the block. These two fields are directly integrated into the block's data structure, making them part of the system's core functionality and ensuring they are considered during block processing. This structure provides the flexibility to retrospectively designate blocks for deletion, representing a crucial advancement in blockchain technology. The "deletion reason" field ensures transparency by providing a clear justification for deletion, thus making the decision-making process traceable. 2. Deletion Log The deletion log describes the process,How a block is deleted from the blockchain. This process consists of three main steps: Request: A network participant submits a deletion request for a specific block. This request is sent to all validators in the blockchain network and must include a valid reason in the "Reason for Deletion" field. Review: Upon receipt of the request, it is reviewed by the network's validators. Validators are special nodes responsible for the integrity of the blockchain. They review the deletion request and ensure that it complies with the predefined rules, particularly regarding legal requirements such as data protection regulations. A specified majority of the validators (for example, two-thirds) must approve the deletion request before the deletion can be authorized. Deletion: If a majority of the validators agree, the deletion flag of the affected block is set to "true." The block is then removed from the active blockchain.The block is removed, but not completely deleted. Instead, the transactions and data of this block are stored in a separate "archive log" maintained outside the active blockchain. The active blockchain then continues without this block. This protocol ensures a structured, secure, and auditable block deletion process. Majority validation by validators ensures that only legitimate requests are approved, thus preserving the integrity of the blockchain. Furthermore, the archive log provides a way to audit data and retain it for legal requirements without impacting the active blockchain. 3. Archive Log The archive log is a separate, inactive data structure specifically designed to store all deleted blocks and their transactions. This structure resides outside the normal blockchain and serves as an archive for deleted data. Every deleted block is stored in the archive log.Each block is stored in this archive log with a timestamp and the corresponding reason for deletion. This ensures that deleted blocks remain available for audits, compliance checks, or regulatory requirements, even though they are no longer part of the active blockchain. The archive log allows the blockchain's history to remain fully transparent, even after data deletion. This is particularly important in areas where data deletion is legally mandated, but transaction traceability must be maintained. This enables a company to ensure both data protection and the necessary auditability. 4. Integrity Assurance After a block is deleted, the blockchain performs a comprehensive integrity check. This includes recalculating the cryptographic hashes for all subsequent blocks to ensure that the links in the blockchain remain intact. Since everyIf a block in the blockchain contains a hash of the previous block, it is necessary to adjust the hashes of the remaining blocks after a block deletion. This recalculation is performed by specialized software that ensures the consistency of the blockchain is maintained. The blockchain is also checked for consistency errors to ensure that no inconsistencies arise from the deletion. All participating nodes in the network perform the hash calculations decentrally, and the results are validated to guarantee that the blockchain continues to function correctly. The automatic recalculation of hashes after a deletion ensures that the blockchain remains unchanged and tamper-proof. These consistency checks ensure that the blockchain remains just as secure and immutable after a block is deleted as it was before. This prevents potential manipulations or security vulnerabilities that could arise from such actions.5. Technical and Compliance Aspects: The blockchain is designed to comply with technical and regulatory requirements, such as the General Data Protection Regulation (GDPR). This means that personal data can be deleted upon request without affecting the fundamental structure of the blockchain. The introduction of the archive log and deletion flags ensures that deletions remain traceable while simultaneously meeting legal requirements for data erasure. Validators within the network are responsible for verifying that each deletion request is reviewed in accordance with applicable laws. This could include additional steps, such as verifying the identity of the requester or ensuring that the deletion does not violate other legal obligations. These enhancements make the blockchain both flexible and compliant with legal requirements.Companies can fulfill legal obligations to delete data without compromising the immutability and integrity of the blockchain. This is particularly important in highly regulated industries such as finance, healthcare, or when handling personal data. The following are some examples of aspects and advantages of the present invention. Flexibility: The ability to delete blocks retrospectively significantly expands the application range of blockchain. Use cases that were previously excluded because permanent storage was undesirable or impossible can now be implemented. Compliance: The invention allows companies to comply with legal requirements for data deletion, especially those related to data protection laws such as the GDPR, without jeopardizing the fundamental principles of blockchain technology. This enables companies to simultaneously leverage the advantages of blockchain while fulfilling their legal obligations.Transparency and traceability are fulfilled: The archive log and the associated deletion reasons ensure that the entire history of the blockchain is fully documented, even after blocks have been deleted. This ensures that every deletion can be traced, which strengthens the system's transparency. The present invention represents a significant extension of blockchain technology, as it allows blocks to be deleted retroactively without compromising the integrity of the blockchain. It offers flexibility to respond to changing legal requirements while simultaneously ensuring that the transparency and security of the blockchain are maintained. The combination of a deleteable block structure, a standardized deletion protocol, an archive log, and mechanisms for ensuring integrity makes this system a versatile solution that enables blockchain systems to be used in new fields of application. Figures 3 and 4 illustrate this.The following process steps are illustrated as examples. 1. Extension of the block structure: 1.1 Deletion flag ^Each block is extended by an additional data structure called the "deletion flag". ^The deletion flag is a boolean value (true / false) that is set to false by default. 1.2 Deletion reason: ^An additional field that stores the reason for deletion as text.^ This field remains empty until a deletion request is approved. 2. Deletion log: 2.1 Request submission: ^A deletion request is submitted to the blockchain network, containing the identification of the block to be deleted (e.g., by its hash value) and the deletion reason. ^The requester must authenticate and authorize themselves to the network to ensure that only authorized entities can submit deletion requests. This is usually the administrator of the blockchain network. 2.2 Review of the request: ^Validators (network nodes responsible for validation) review the deletion request. ^TheThe review process includes verifying the authenticity of the requester and evaluating the reason for deletion. A vote is held among the validators, requiring a predefined majority (e.g., 75%) to approve the request. This majority is provided by the mainchain, which always acts as the primary entity. 3. Block Deletion: 3.1 Activating the Deletion Flag: After approval, the deletion flag of the corresponding block is set to true. The reason for deletion is entered in the corresponding field. Subsequently, the file associated with this block is no longer decryptable and therefore unreadable. Block Removal: The block is removed from the active blockchain and transferred to a separate "archive log." The archive log is a separate data structure that stores all deleted blocks and their transactions. Blockchain Recalculation and Validation: Hash Recalculation: All subsequent blocks must be recalculated to ensure the...To ensure the integrity of the blockchain.^ This includes recalculating the hash values ​​for all affected blocks. Consistency check:^ The blockchain is checked for consistency by validating the hash values ​​and transaction data.^ Each block is checked for integrity to ensure that no manipulation has occurred. Archive log: Storing deleted blocks:^ Deleted blocks and their transactions are stored in the archive log.^ The archive log is only accessible to authorized entities to ensure data protection and compliance. Access and transparency:^ The archive log makes it possible to trace the history of the blockchain, even if data has been deleted.^ Transparency is ensured through detailed logging of deletion processes and access controls. By viewing the archive log, data and block structures that have already been deleted cannot be reconstructed. 6. Legal and compliance aspects: 6.1 FulfillmentRequirements: ^The system enables compliance with legal requirements, such as the GDPR, by supporting the deletion of personal data upon request.^ The introduction of the archive log ensures that the deletion process remains transparent and traceable. 6.2 Data Protection: ^Access controls and authentication mechanisms ensure that only authorized entities can access deleted data. 7. Implementation and Integration: 7.1 Software Architecture: ^Implementation takes place in the blockchain by extending the existing data structures and protocols. ^The deletion protocol is integrated into the existing network protocol as an additional consensus mechanism. 7.2 Network Updates: ^Work can continue as usual within a database application. By using the deletion function, encrypted files are irretrievably destroyed. Figure 4 shows the blockchain according to Figure 3 after the deletion process according to the invention. Below isThe deleted block is applied. The chains are then reconnected using references and, if necessary, recalculating the hash values. The following are example functions in C# for technical traceability, illustrating the method according to one aspect of the present invention: using System; using System.Collections.Generic; using System.Security.Cryptography; using System.Text; public class Block { public int Index { get; set;} public DateTime Timestamp { get; set;} public string PreviousHash { get; set;} public string Hash { get; set;} public List <string>Transactions { get; set;}public bool IsDeleted { get; set;} public string DeletionReason { get; set;} public Block(int index, DateTime timestamp, List <string>transactions, string previousHash = "") { Index = index; Timestamp = timestamp; Transactions = transactions; PreviousHash = previousHash; Hash = CalculateHash(); IsDeleted = false; DeletionReason = string.Empty;} public string CalculateHash() { SHA256 sha256 = SHA256.Create(); byte[] inputBytes = Encoding.ASCII.GetBytes($"{Index}- {Timestamp}-{PreviousHash}-{string.Join(",", Transactions)}- {IsDeleted}"); byte[] outputBytes = sha256.ComputeHash(inputBytes); return Convert.ToBase64String(outputBytes);}} public class Blockchain { public List <block>Chain { get; set;} public List <block>ArchiveLog { get; set;} public Blockchain() { Chain = new List <block>{ CreateGenesisBlock()}; ArchiveLog = new List <block>();} private Block CreateGenesisBlock() { return new Block(0, DateTime.Now, new List <string>(), "0");} public Block GetLatestBlock() { return Chain[Chain.Count - 1];} public void AddBlock(Block newBlock) { newBlock.PreviousHash = GetLatestBlock().Hash; newBlock.Hash = newBlock.CalculateHash(); Chain.Add(newBlock);} public void DeleteBlock(int index, string reason) { if (index <= 0 || index >= Chain.Count) { throw new ArgumentException("Invalid block index for deletion.");} Block blockToDelete = Chain[index]; blockToDelete.IsDeleted = true; blockToDelete.DeletionReason = reason; ArchiveLog.Add(blockToDelete); Chain.RemoveAt(index); / / Recalculate hashes for remaining blocks for (int i = index; i < Chain.Count; i++) { Chain[i].PreviousHash = i == 0 ? "0" : Chain[i - 1].Hash; Chain[i].Hash = Chain[i].CalculateHash();}} public bool IsValidChain() { for (int i = 1; i < Chain.Count; i++) { Block currentBlock = Chain[i]; Block previousBlock = Chain[i - 1];if (currentBlock.Hash != currentBlock.CalculateHash()) { return false;} if (currentBlock.PreviousHash != previousBlock.Hash) { return false;}} return true;}} The following is an example usage according to one aspect of the present invention: public class Program { public static void Main(string[] args) { Blockchain myBlockchain = new Blockchain(); myBlockchain.AddBlock(new Block(1, DateTime.Now, new List. <string>{ "Tx1", "Tx2"})); myBlockchain.AddBlock(new Block(2, DateTime.Now, new List <string>{ "Tx3"})); myBlockchain.AddBlock(new Block(3, DateTime.Now, new List <string>{ "Tx4", "Tx5"})); Console.WriteLine("Blockchain valid: " + myBlockchain.IsValidChain()); / / Deleting Block 2 myBlockchain.DeleteBlock(2, "Data correction"); Console.WriteLine("Blockchain valid after deletion: " + myBlockchain.IsValidChain()); foreach (Block block in myBlockchain.Chain) { Console.WriteLine($"Block {block.Index} - Hash:{block.Hash}, Previous Hash: {block.PreviousHash}");} Console.WriteLine("Archive Log:"); foreach (Block block in myBlockchain.ArchiveLog) { Console.WriteLine($"Deleted Block {block.Index} - Reason: {block.DeletionReason}");}}}Explanation of the implementation according to one aspect of the present invention: 1. Block Class: Contains basic information such as index, timestamp, previous hash, current hash, transactions, deletion flag, and deletion reason. Calculates the block's hash based on its data. Blockchain Class: Initializes the blockchain with a genesis block.^ Adds new blocks, updates the previous hash, and calculates the new hash. ^ Implements a DeleteBlock method that marks a block as deleted, stores the reason, and moves the block to the archive log. The blockchain is then recalculated to ensure integrity. ^ Checks the validity of the blockchain using the IsValidChain method. 3. Program Class: ^ Demonstrates the use of the blockchain, including adding blocks and deleting a block. Spacechain block usage within the blockchain: Spacechain blocks within a blockchain are specialized blocks that allow the creation of a separate but interconnected chain (spacechain) within the main blockchain. This structure can be used to manage specific transactions or data independently of the main chain while still utilizing the security and integrity of the main blockchain.Spacechain blocks can have various uses, such as performing specific tasks, testing new features, or hosting applications with different requirements than the main blockchain. Features of Spacechain Blocks (Blocks of the Separate Blockchain): 4. Embedded Chain: Spacechain blocks form their own chain within the main blockchain. This chain can have its own rules and protocols, independent of the main blockchain. 5. Link to the Main Blockchain: Each Spacechain block is linked to a block on the main blockchain. This ensures that the Spacechain continues to benefit from the security and integrity of the main blockchain. 6. Separate Validation: Spacechain blocks can use their own consensus mechanisms and validation protocols. This allows for flexible adaptation to specific requirements or testing of new technologies. 7.Use Cases: Spacechain blocks can be used for various purposes, such as testing features, executing special transactions, managing applications, or hosting smart contracts that are independent of the main blockchain. Structure of a Spacechain Block: A Spacechain block has a similar structure to a regular block in the main blockchain, but contains additional fields and links to Spacechain: Index: The index of the block in Spacechain. Timestamp: The timestamp of when the block was created. Previous Hash: The hash of the previous block in Spacechain. Hash: The current hash of the block. Transactions: The transactions contained in the block. Link to Main Blockchain: A reference to the corresponding block in the main blockchain. Spacechain-Specific Data: Data specific to Spacechain, such as metadata or special transaction data.Example of a Spacechain Block Structure in C# The following is a simple example of implementing a Spacechain block within a blockchain in C#: using System; using System.Collections.Generic; using System.Security.Cryptography; using System.Text; public class SpacechainBlock { public int Index { get; set;} public DateTime Timestamp { get; set;} public string PreviousHash { get; set;} public string Hash { get; set;} public List. <string>Transactions { get; set;} public string MainChainBlockHash { get; set;} / / Verknüpfung zur Haupt-Blockchain public SpacechainBlock(int index, DateTime timestamp, List <string>transactions, string previousHash = "", string mainChainBlockHash = "") { Index = index; Timestamp = timestamp; Transactions = transactins; PreviousHash = previousHash; MainChainBlockHash = mainChainBlockHash; Hash = CalculateHash();} public string CalculateHash() { SHA256 sha256 = SHA256.Create(); byte[] inputBytes = Encoding.ASCII.GetBytes($"{Index}- {Timestamp}-{PreviousHash}-{string.Join(",", Transactions)}- {MainChainBlockHash}"); byte[] outputBytes = sha256.ComputeHash(inputBytes); return Convert.ToBase64String(outputBytes);}} public class Spacechain { public List <spacechainblock>Chain { get; set;} public Spacechain() { Chain = new List <spacechainblock>{ CreateGenesisBlock()};} private SpacechainBlock CreateGenesisBlock() { return new SpacechainBlock(0, DateTime.Now, new List <string>(), "0", "0");} public SpacechainBlock GetLatestBlock() { return Chain[Chain.Count - 1];} public void AddBlock(SpacechainBlock newBlock) { newBlock.PreviousHash = GetLatestBlock().Hash; newBlock.Hash = newBlock.CalculateHash(); Chain.Add(newBlock);} public bool IsValidChain() { for (int i = 1; i < Chain.Count; i++) { SpacechainBlock currentBlock = Chain[i]; SpacechainBlock previousBlock = Chain[i - 1];if (currentBlock.Hash != currentBlock.CalculateHash()) { return false;} if (currentBlock.PreviousHash != previousBlock.Hash) { return false;}} return true;} } Using Spacechain in the Main Blockchain: The following is an example of how Spacechain can be integrated into the main blockchain: public class MainBlockchain { public List <block>Chain { get; set;} public List <spacechain>Spacechains { get; set;} public MainBlockchain() { Chain = new Lst <lock>{ CreateGenesisBlock()}; Spacechains = new List <spacechain>();} private Block CreateGenesisBlock() { return new Block(0, DateTime.Now, new List <string>(),} public Block GetLatestBlock() { return Chain[Chain.Count - 1];} public void AddBlock(Block newBlock) { newBlock.PreviousHash = GetLatestBlock().Hash; newBlock.Hash = newBlock.CalculateHash(); Chain.Add(newBlock);} public void AddSpacechain(Spacechain newSpacechain) { Spacechains.Add(newSpacechain);} public bool IsValidChain() { for (int i = 1; i < Chain.Count; i++) { Block currentBlock = Chain[i]; Block previousBlock = Chain[i - 1];if (currentBlock.Hash != currentBlock.CalculateHash()) { return false;} if (currentBlock.PreviousHash != previousBlock.Hash) { return false;}} foreach (var spacechain in Spacechains) { if (!spacechain.IsValidChain()) { return false;}} return true;}} public class Program { public static void Main(string[] args) { MainBlockchain myBlockchain = new MainBlockchain(); / / Hinzufügen von Blöcken zur Haupt-Blockchain myBlockchain.AddBlock(new Block(1, DateTime.Now, new List <string>{ "Tx1", "Tx2"})); myBlockchain.AddBlock(new Block(2, DateTime.Now, new List <string>{ "Tx3"})); / / Create and add a spacechain Spacechain mySpacechain = new Spacechain(); mySpacechain.AddBlock(new SpacechainBlock(1, DateTime.Now, new List <string>{ "SC Tx1", "SC Tx2"}, mySpacechain.GetLatestBlock().Hash, myBlockchain.GetLatestBlock().Hash)); myBlockchain.AddSpacechain(mySpacechain); Console.WriteLine("Blockchain valid: " + myBlockchain.IsValidChain()); / / Output the main blockchain foreach (Block block in myBlockchain.Chain) { Console.WriteLine($"Block {block.Index} - Hash:{block.Hash}, Previous Hash: {block.PreviousHash}");} / / Output the Spacechain foreach (SpacechainBlock block in mySpacechain.Chain) { Console.WriteLine($"Spacechain Block {block.Index}- Hash: {block.Hash}, Previous Hash: {block.PreviousHash},MainChain Block Hash: {block.MainChainBlockHash}"); A spacechain is a special chain within the main blockchain, designed for specific tasks. Essentially, the spacechain represents a self-contained structure connected to the main blockchain.This separate chain allows for the execution of specialized processes or applications without directly impacting or burdening the main blockchain. However, the spacechain remains tightly linked to the main blockchain through specific mechanisms. Each block in the spacechain contains references to the corresponding blocks in the main blockchain. This link ensures a clear and traceable connection between the two chains, allowing all spacechain data to remain synchronized with the main blockchain. One possible feature of the spacechain is the ability to implement separate validation. This means it can implement its own validation protocols, independent of the main blockchain's validation mechanisms. This allows the spacechain to be optimized for specific tasks or use cases that may have different requirements regarding security, speed, or processing logic.This independence allows for the definition of specific validation rules that do not necessarily have to meet the stringent requirements of the main blockchain. In practice, this concept offers a flexible and extensible structure that supports various use cases. Spacechains can be used for a wide range of applications, including testing, prototyping, or tasks that need to be executed in isolation from the main blockchain. They also offer the possibility of implementing specialized functions, such as for research purposes or industry-specific requirements, without compromising the integrity and efficiency of the main blockchain. This flexibility allows spacechains to contribute to the realization of different scenarios and adaptation to specific requirements, significantly improving the extensibility and adaptability of the entire blockchain system.The so-called spacechain can also be referred to as the separate blockchain according to the invention. Spaceblocks can also be referred to as blocks of the separate blockchain. Figure 5 shows a schematic blockchain in which the middle three blocks are to be deleted. A conventional blockchain is provided, comprising blocks and references as shown above. These blocks and references form a linked list, and each block has at least one parameter, as shown by way of an example of a block and its parameter list. Furthermore, the conventional blockchain is operated, as shown above, in a self-contained, network-based infrastructure, for example, a company network, comprising network nodes, whereby the conventional blockchain is redundantly distributed across at least a subset of the network nodes, which is not shown here.Only the logical structure of the blockchain without redundancies is shown. Furthermore, a deletion request of three blocks in the middle of the conventional blockchain is created by a network node and transmitted to other network nodes. These are typically servers within the network, or the network nodes can also run as agents on a single computer. If the deletion request is approved by the network nodes according to a approval metric, a separate blockchain is created, as shown below. This separate blockchain contains a reference to each block of the conventional blockchain to be deleted. This is indicated by arrows from bottom to top. Thus, the conventional blockchain is shown above, and the separate blockchain below.< / string> < / string> < / string> < / string> < / spacechain> < / lock> < / spacechain> < / block> < / string> < / spacechainblock> < / spacechainblock> < / string> < / string> < / string> < / string> < / string> < / string> < / block> < / block> < / block> < / block> < / string> < / string>

Claims

Claims 1. A method for securely removing blocks from an existing blockchain in a closed infrastructure, comprising: - providing (100) a conventional blockchain comprising blocks and references which form a linked list and each block has at least one parameter; - operating (101) the conventional blockchain in a self-contained, network-technically configured infrastructure comprising network nodes, wherein the conventional blockchain is redundantly distributed (102) across at least a subset of the network nodes; - creating (103) a deletion request of at least one block of the conventional blockchain by a network node, which is transmitted (104) to other network nodes;- upon a positive decision (105) of the deletion request by the network nodes according to a decision metric, a creation (106) of a separate blockchain, containing at least one block with a deletion entry, wherein each block of the separate blockchain contains a reference to a block of the conventional blockchain to be deleted; - an execution (107) of the deletion request according to the separate blockchain by the corresponding network nodes;and- encrypting (108) the block to be deleted before storing it in the conventional blockchain using a symmetric cryptographic key, storing the encrypted block in the conventional blockchain, keeping the associated key exclusively in a key management facility within the closed infrastructure, and subsequently irretrievably deleting the key from all storage media, including volatile storage, non-volatile storage and backup copies, thereby rendering the stored block technically impossible to decrypt.; 2. A method according to claim 1, characterized in that, after the deletion request is executed, blocks following the blocks to be deleted are adjusted.

3. A method according to claim 1 or 2, characterized in that, after the deletion request is executed, blocks following the blocks to be deleted are adjusted with respect to their stored references, checksums, hash values, consistency information, and / or integrity information.

4. A method according to any of the preceding claims, characterized in that blocks to be deleted are stored in a blockchain other than the conventional blockchain and / or an archive.

5. A method according to any of the preceding claims, characterized in that the decision metric corresponds to a majority vote or a defined approval threshold. 6.A method according to any one of the preceding claims, characterized in that the decision metric is evaluated depending on a validity check, an authenticity check, and / or existing blocks.

7. A method according to any one of the preceding claims, characterized in that the execution (107) of the deletion request is carried out such that the at least one block is deleted, the reference to the block is removed, the block is overwritten, decryption information is discarded, at least one parameter of the block is deleted, a hash value is modified, and / or the block is encrypted.

8. A method according to any one of the preceding claims, characterized in that the deletion request has at least one deletion reason and / or a recovery attempt is made depending on this deletion reason. 9.A method according to any of the preceding claims, characterized in that the conventional blockchain is imported into the closed infrastructure via an interface. A method according to any of the preceding claims, characterized in that the blocks of the conventional blockchain each refer to a document which is locked for processing upon a corresponding deletion request.

11. A method according to any of the preceding claims, characterized in that the closed, network-technically configured infrastructure is technically separated from any other connected network.

12. A method according to any of the preceding claims, characterized in that the network nodes are distributed within the infrastructure as hardware and / or software components.

13. A system arrangement for securely removing blocks from an existing blockchain in a closed infrastructure, comprising: - an interface unit configured for providing (100) a conventional blockchain comprising blocks and references which form a linked list and each block has at least one parameter; - an infrastructure configured for operating (101) the conventional blockchain in the self-contained, network-technically configured infrastructure comprising network nodes.wherein the conventional blockchain is redundantly distributed across at least a subset of the network nodes (102);- a request unit is set up to create (103) a deletion request of at least one block of the conventional blockchain by a network node, which is transmitted (104) to other network nodes;- a blockchain unit is set up upon a positive decision (105) of the deletion request by the network nodes according to a decision metric to create (106) a separate blockchain, containing at least one block with a deletion entry,wherein each block of the separate blockchain contains a reference to a block of the conventional blockchain to be deleted; - a deletion unit established to execute (107) the deletion request according to the separate blockchain by the appropriate network nodes; and - a cryptographic unit established to encrypt (108) the block to be deleted before storing it in the conventional blockchain using a symmetric cryptographic key, further established to store the encrypted block in the conventional blockchain, to retain the associated key exclusively in a key management facility within the closed infrastructure, and further established to subsequently and irrevocably delete the key from all storage media, including volatile storage, non-volatile storage and backup copies,which renders decryption of the stored block by technical means no longer feasible.

14. Computer program product comprising instructions which, when executed by at least one computer, cause it to perform the steps of the method according to any one of claims 1 to 12.

15. Computer-readable storage medium comprising instructions which, when executed by at least one computer, cause it to perform the steps of the method according to any one of claims 1 to 12.

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