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Distributed Data Structures (DDSs)
Published in Suman Saha, Shailendra Shukla, Advanced Data Structures, 2019
Distributed HashingA distributed hash table (DHT) is a class of a decentralized distributed system that provides a lookup service similar to a hash table: (key, value) pairs are stored in a DHT, and any participating node can efficiently retrieve the value associated with a given key. Responsibility for maintaining the mapping from keys to values is distributed among the nodes, in such a way that a change in the set of participants causes a minimal amount of disruption. This allows a DHT to scale to extremely large numbers of nodes and to handle continual node arrivals, departures, and failures. DHTs form an infrastructure that can be used to build more complex services, such as cooperative Web caching, distributed file systems, domain name services, instant messaging, multicast, and also peer-to-peer file sharing and content distribution systems. Notable distributed networks that use DHTs include BitTorrent’s distributed tracker, the Coral Content Distribution Network, the Kad network, the Storm botnet, the Tox instant messenger, Freenet and the YaCy search engine.
Mobile Internet
Published in K.R. Rao, Zoran S. Bojkovic, Dragorad A. Milovanovic, Wireless Multimedia Communications, 2018
K.R. Rao, Zoran S. Bojkovic, Dragorad A. Milovanovic
A P2P overlay network is a distributed network that relies on the computing power and bandwidth of peer nodes in the network. Unlike the client/server model, each node participates in the P2P overlay network as a peer with equal responsibility. In P2P overlay networks, since there is no central entity to control overall tasks, it has no role in these networks. Also, P2P overlay networks provide self-organization and load-balancing functions in a distributed manner. Another attractive feature is the technique used for locating and retrieving a desired item (e.g., a file in file-sharing applications). For more efficient locating/retrieving operations, a distributed hash table (DHT) has been introduced. The DHT is a decentralized and distributed system where all items and peer nodes are identified by unique keys. In the DHT, the ownership of keys is distributed among participating peer nodes and hence the peer nodes can efficiently route messages to the owner of any given key. Therefore, the DHT is scalable to a large number of nodes and can handle continual node arrivals and failures. These features enable the DHT to be widely accepted for large-scale P2P networking.
A Blockchain Based Decentralized Identifiers for Entity Authentication in Electronic Health Records
Published in Cogent Engineering, 2022
Manoj T, Krishnamoorthi Makkithaya, Narendra V G
The whole principle of decentralization is based on the simple idea that a transaction for a transfer of commodity/asset between two parties is approved through the consensus mechanism by the participating nodes. This transaction is recorded in an immutable distributed ledger. Blockchain is the first pragmatic distributed ledger protocol that pioneered the idea of decentralization into the financial transaction settlement. Later, the framework was generalized in the healthcare ecosystem by introducing programming capabilities using smart contracts. Yue et al. (2016) initiated the idea to adopt blockchain in the design of healthcare for decentralized identity management. MedRec (Azaria et al., 2016) is the first working prototype using blockchain for accessing the health records based on Ethereum smart contracts. Liang (2019) proposed a design for identity management and verification using blockchain technology to offer flexibility in health record access and enhanced protection for patient data. An efficient authentication mechanism for hospital networks based on blockchain was proposed by Yazdinejad et al. (2020) for the identification of distributed patients. Mubashar et al. (2021) designed a distributed hash table architecture based on IPFS and blockchain for the faster retrieval of health records.
The impact factors on the competence of big data processing
Published in International Journal of Computers and Applications, 2022
Wei Li, William W. Guo, Michael Li
To make such an investigation, we need two types of abstraction. The first one is an algorithm for processing big data problems. In this aspect, although the analysis of big data is still an open problem, MapReduce [4] has been a successful general model. MapReduce has been chosen by this paper as a generic abstraction to represent the operations of distributing data, parallelizing computation, and synthesizing results. These operations are essentially necessary for big data processing and important for the competence of processing. The second abstraction is a unified platform that is able to expose the impacts of a variety of factors. In this aspect, the distributed hash table (DHT) protocol Chord [5] has been chosen to build such an abstract platform, representing the dynamics of computing nodes, the communication cost, and the heterogeneous compute-capacity of each computing node. In addition, Chord ensures a reliable overlay to provide storage and enables a lookup service for the stored items even though none of the individual nodes is reliable. The aforementioned two abstractions are enhanced through the proposed virtual tasks, which are certain of compute-intensity and data-intensity but independent of any particular applications. Such abstraction and enhancement eliminate the difference introduced by languages choices, OS options, middleware overhead, and enable fair comparison of a variety of computing strategies.
Practical overview of security issues in wireless sensor network applications
Published in International Journal of Computers and Applications, 2018
Harish Radhappa, Lei Pan, James Xi Zheng, Sheng Wen
George and Parani [26] study is based on detection of clones in a wireless sensor networks. Cloning attack is a condition where the attacker behaves as one of the actual node by disguising. Cloning or impersonation attacks could be fatal in wireless sensor network applications. The cloning usually takes place in medium-scale and small-scale applications. If an attacker could perform this attack the target node could lose the critical data and also consequences could be impersonation of entire hardware. Cloning attack usually takes form of tampering attack in a sensor network [26]. A distributed hash table approach provides decentralized scheme along with checking of the keys from hash table. The detection may be initiated by sending a request by initiator. Distributed hash table contains the entire records of key pairs distributed to the genuine nodes [26]. This technique basically eliminates the unauthorized data access. The main strength of the proposed algorithm is that the multi-identifications from the attacker could be identified which is basically termed as Sybil attack. The main weakness or drawback of this technique is that the detection would take place once the probabilistic data are shared with the destination. Having neglected Sybil attack at later stages may lead to loss of data and impersonation as the attacker would have gained entire access to the network.