[vc_row][vc_column][vc_custom_heading text=“Toward a distributed, private, and secure IoT using Blockchain“ font_container=“tag:h2|font_size:38|text_align:left|color:%23e30613″ use_theme_fonts=“yes“ css=“.vc_custom_1528289952655{margin-top: -25px !important;}“][vc_column_text]Ein Beitrag von: Ali Dorri, Salil S. Kanhere, University of New South Wales, Raja Jurdak, Commonwealth Scientific and Industrial Research Organisation, Praveen Gauravaram, Tata Consultancy Services Limite[/vc_column_text][vc_custom_heading text=“Kurz und bündig:“ font_container=“tag:h3|font_size:17|text_align:left|color:%23ffffff“ use_theme_fonts=“yes“ css=“.vc_custom_1519747666609{padding-left: 15px !important;background-color: #f07d00 !important;}“][vc_column_text css=“.vc_custom_1528815519992{border-top-width: 1px !important;border-right-width: 1px !important;border-bottom-width: 1px !important;border-left-width: 1px !important;padding-top: 10px !important;padding-right: 10px !important;padding-bottom: 10px !important;padding-left: 10px !important;background-color: #eaeaea !important;border-left-color: #aaaaaa !important;border-left-style: solid !important;border-right-color: #aaaaaa !important;border-right-style: solid !important;border-top-color: #aaaaaa !important;border-top-style: solid !important;border-bottom-color: #aaaaaa !important;border-bottom-style: solid !important;border-radius: 1px !important;}“]

Blockchain hat das Potenzial, die Sicherheits- und Datenschutzprobleme des IoT zu lösen. Dabei überzeugt Blockchain in den Bereichen Sicherheit, Datenschutz, Unveränderlichkeit und Überprüfbarkeit. Das IoT hat jedoch auch strenge Anforderungen bezüglich Skalierbarkeit und Gemeinkosten sowie Durchsatz und Recht auf Vergessenwerden. Diesbezüglich muss die Blockchain zukünftig noch optimiert werden.

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The benefits afforded by blockchain technology make it an attractive solution to address the security and privacy challenges in the global network connecting millions of devices known as the Internet of Things (IoT). But applying blockchain for IoT is not straightforward, as existing blockchain instantiations cannot be readily adopted in the IoT context.

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Blockchain is an immutable, auditable, and timestamped ledger of blocks that is used for storing and sharing data in a distributed manner. The stored data can be payment history, e.g. Bitcoin, a contract or even personal data. Blockchain is managed in a distributed manner by all participating nodes in the underlying peer-to-peer network. In recent years, blockchain has attracted tremendous attention from practitioners and academics in different disciplines (including law, finance, and computer science) due to its salient features which include decentralization, auditability, immutability, security and privacy.

The basic communication primitive between participants in blockchain is known as a transaction. Transactions are broadcast to all participants in the network for full transparency. Nodes in the network may choose to serve as a miner by collecting transactions and forming a block. The miner then appends, i.e., mines, the new block to the blockchain by following a consensus algorithm. Mining entails solving a computationally demanding, hard-to-solve, and easy-to-verify puzzle. Miners are offered financial or other incentives for allocating resources to solve the puzzle. Each block maintains the hash of its previous block, thus creating a chain of blocks and forming the blockchain. Modification of the content of the blocks, i.e., transactions, is not possible as the hash of the changed block would not match with the hash in the following block. The consensus algorithm and the decentralized architecture of blockchain build a trusted network over untrusted users. All communication between nodes is encrypted which protects against eavesdropping. Each transaction contains the hash of the transaction content digitally signed by the transaction generator to achieve data integrity. In order to ensure privacy, blockchain relies on the anonymity provided by a public key for each new transaction generated by a node. In other words, the node changes its identity each time it starts a communication with another node in the network.

The benefits afforded by blockchain technology make it an attractive solution to address the security and privacy challenges in the global network connecting millions of devices known as the Internet of Things (IoT). This network of cheap sensors and interconnected things collects information from our built and natural environments at unprecedented resolution. Indeed, such detailed knowledge will improve efficiencies and deliver advanced services in a wide range of application domains including pervasive healthcare and smart city services. However, the increasingly invisible, dense and pervasive collection, processing and dissemination of data in the midst of people’s private lives gives rise to serious security and privacy concerns. On the one hand, this data can be used to offer a range of sophisticated and personalized services that add value to users. On the other hand,embedded in this data is information that can be used to algorithmically construct a virtual biography of our activities, revealing private behavior and lifestyle patterns. The privacy risks of IoT are exacerbated by the lack of fundamental security safeguards in many of the first generation IoT products on the market. Numerous security vulnerabilities have been identified in connected devices ranging from smart locks to vehicles. Conventional security and privacy methods for IoT suffer from the following challenges:

Resource consumption: Most IoT devices have limited resources, including bandwidth, computation, and memory, which is incompatible with the requirements of complex security solutions.

Centralization: Current IoT ecosystems rely on centralized brokered communication models where all devices are identified, authenticated and connected through cloud servers. This model is unlikely to scale as billions of devices are interconnected. Moreover, cloud servers will remain a bottleneck and a single point of failure that can disrupt the entire network.

Lack of privacy: Conventional privacy preserving methods rely on revealing noisy or summarized data to the data requester. In contrast, several IoT applications require users to reveal precise data to the service providers to receive personalized services.

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Blockchain has the potential to address the aforementioned security and privacy concerns in IoT. Blockchain introduces a high level of anonymity. Each participating node uses a public key as its identity. To communicate with each IoT user or device, the participating node employs a fresh key to prevent other nodes from tracking its transactions with other nodes.

All transactions, are logged in the blockchain in an immutable tamper-resistant way. Thus, IoT users can monitor who accessed their devices, what information is transmitted by their devices and to whom, and how frequently their IoT devices are accessed. The transactions in the blockchain contain the hash of the data exchanged to ensure data integrity. Thus, any attempts to alter the data of an IoT device can be readily detected.

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Despite the aforementioned advantages of using blockchain in IoT, existing blockchain instantiations cannot be readily adopted in the IoT context for the following reasons:

• Scalability and overheads: In a typical blockchain implementation, all blocks are broadcast to and verified by all nodes. This leads to significant scalability issues since the broadcast traffic and processing overheads would increase quadratically with the number of nodes in network. The associated overheads are intractable as many IoT devices have limited bandwidth connections.
• Latency: There is a non-trivial delay associated with ensuring that a transaction is confirmed by nodes participating in the blockchain. For example, in Bitcoin, it can take up to 30 minutes for a transaction to be confirmed. Most IoT applications have stricter delay requirements, e.g., a service provider requesting data from a smart home sensor should not have to wait for several minutes as the data may be required to offer real-time services to the user.
• Throughput: In blockchain, the throughput is defined as the number of transactions that can be stored in the ledger. Classical instantiations of blockchain have limited throughput. For example, Bitcoin throughput is 7 transactions per second. However, the number of transactions in the IoT ecosystem would far exceed such limits due to extensive interactions between various entities.
• The right to be forgotten: In blockchain, all transactions and their corresponding data must be stored permanently by all participants. Thus, at any point in time the history of interactions of a user with any other participant in IoT can be tracked. Additionally, attackers might succeed in linking multiple IoT devices to a user and then deanonymize the user. In this case, the attacker can also track all history of the interactions of the IoT devices of the user. Thus, there is a need for IoT users to have the right for their data or transactions to be removed from the blockchain to guarantee their privacy.

Recently, several new blockchain frameworks have been proposed to address the aforementioned issues. In our recent work titled “lightweight scalable blockchain (LSB)” we proposed a distributed timebased consensus algorithm that requires miners to wait for a period of time prior to mining a block in place of solving a resource consuming puzzle. A distributed throughput algorithm ensures that the blockchain is self-scaling, i.e., blockchain throughput increases as the number of nodes increase. In another work, we designed a memory optimized and flexible blockchain (MOF-BC) that gives the people the right for their data to be forgotten. IoTA has proposed a ledger-based system which eliminates the notion of blocks and mining. The key innovation behind IoTA is the “tangle”, which is essentially a directed acyclic graph (DAG). In IoTA, each user must verify transactions of two other users prior to be able to generate his own transaction.

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In recent years blockchain has attracted tremendous attention from academia and practitioners in different disciplines due to its salient features including privacy, security, and immutability. Blockchain can serve as a framework to address security and privacy challenges of large-scale networks such as IoT. The IoT devices collect a wide range of privacy sensitive information from the everyday lives of the users. Thus, security of these devices and their communications with other devices, as well as the privacy of the users become highly challenging. Blockchain has the potential to overcome the outlined challenges. Blockchain offers increased privacy by offering anonymity to the users. Due to the immutable nature of the blockchain, all transactions between IoT participants including the exchanged data or access to the IoT devices are logged into the blockchain, which affords IoT users to have full control over their privacy. However, applying blockchain for IoT is not straightforward and presents a number of challenges including scalability and throughput.

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