@PHDTHESIS{ 2021:1216640457,
 	title = {Multi-level consensus algorithm for appendable-block blokchains in iot environments},
 	year = {2021},
 	url = "http://tede2.pucrs.br/tede2/handle/tede/9641",
 	abstract = "Currently, there are different devices collecting data and providing services through the Internet. Some of these devices - or just things - collaborate to exchange information and use them to make smarter decisions in an environment called Internet of Things (IoT). Connecting everyday physical objects is creating new business models, improving processes and reducing costs. However, security issues in IoT can have a high impact on both business and physical assets. Recently, the blockchain technology emerged as a possible solution to overcome security issues in IoT. Despite of that, traditional blockchains (such as Bitcoin or Ethereum) are not well suited to the resource-constrained nature of IoT devices or to the large volume of information expected from typical IoT environments. The adoption of a lightweight blockchain framework called appendable-block blockchain has been proposed to be used in IoT environments. This blockchain adopts a different data structure, based on blocks with decoupled and appendable data. While this blockchain presented good performance results (few milliseconds to append a new block), the lack of a consensus algorithm makes it vulnerable to many security issues. Another problem in current blockchain implementations is the lack of discussion on users behavior in different contexts and how it could be adapted for different consensus algorithms. To overcome this problem, this thesis presents a set of steps to create a multi-level consensus mechanism for different contexts. The main idea is to develop a solution that allows the usage of consensus algorithms at the block level and at the transaction level. Moreover, this solution can help to insertion of information in parallel, separating nodes in contexts. This approach can help to provide a solution that can use different configurations or consensus, according to the requirements of each context in the IoT environment. Finally, the results obtained in the experiments shows that a multi-level consensus can produce a high throughput and low latency to insert new transactions in appendable-block blockchains.",
 	publisher = {Pontifícia Universidade Católica do Rio Grande do Sul},
 	scholl = {Programa de Pós-Graduação em Ciência da Computação},
 	note = {Escola Politécnica}
}