Em blockchain, os nodos completos (NCs) armazenam todas as transações existentes e são responsáveis por validar novos blocos. A quantidade de dados armazenados por NCs vem aumentando significativamente nas principais blockchains, como a do Bitcoin. O excesso de dados de blockchains aumenta a sobrecarga de armazenamento e processamento nos NCs, podendo causar a redução de validadores e armazenadores dos dados e colocando em risco o princípio de descentralização em blockchain. Este artigo propõe um mecanismo de armazenamento dos dados menos custoso para NCs de blockchain. O mecanismo visa diminuir a sobrecarga de armazenamento e processamento nos NCs, e garantir a característica de descentralização da rede.

Em blockchains, nodos completos (NCs) são pares que armazenam e verificam todas as transações contidas nos blocos, enquanto clientes leves (CLs) são aqueles que solicitam apenas os cabeçalhos dos blocosá um NC, realizando verificações mais simples. Para lidar com comportamentos maliciosos, a abordagem convencional para garantir o recebimento dos cabeçalhos originais é solicitá-losá múltiplos NCs e comparar as respostas recebidas. Essa abordagem, contudo, requer que um CL estabeleça conexões seguras com cada NC, o que resulta em maior sobrecarga e tempo de resposta. Nesse contexto, esse trabalho propõe o Distributed Lightweight Client Protocol (DLCP), que demanda criptografar uma requisição de cabeçalhos apenas uma vez para um conjunto de NCs, que, por sua vez, retornam umaúnica resposta para o CL. Avaliações preliminares mostraram que o DLCP provê menor latência que a abordagem convencional e reduz a sobrecarga nos CLs.

In blockchain, full nodes (FNs) are peers that store and verify entire chains of transactions, and light clients (LCs) are those which outsource chain verification to FNs (as they lack computing resources required to do so). In general, LCs perform simpler verification protocols, e.g. Simple Payment Verification (SPV), by offloading the execution of blockchain operations to FNs. To cope with byzantine faults (like malicious behavior), a current approach for blockchain transaction verification is requiring that LCs outsource their requests to multiple FNs, and compare received results. This approach, however, requires that LCs establish secure connections to each FN, which leads to client-side complexity and slower verification. To tackle this issue, we propose Distributed Lightweight Client Protocol (DLCP), a protocol for secure verification in blockchain. In summary, DLCP requires LCs to encrypt a request once, allowing a pre-determined set of FNs to access and process it. Through DLCP, LCs become able to verify whether FNs have agreed on the operation outcome. From some preliminary evaluation, we observed that DLCP decreased computing and communication overhead in LCs, while providing lower latency.

In blockchain, full nodes (FNs) are peers that store and verify entire chains of transactions. In contrast, light clients (LCs) are those with limited resources, and for this reason, they request only block headers from FNs for transac- tion verification—using protocols like Simple Payment Verification (SPV). In an approach to prevent FN tampering on transaction verification (byzantine fault), LCs request block headers from multiple FNs and compare received responses. One problem with this approach is that an LC must connect to each FN and per- form the same cryptographic operations with each one repeatedly, which leads to client-side complexity and slower response. We propose an alternate approach to tackle this issue, in which LCs can encrypt a request for block headers only once, and send that request to a predetermined set of FNs to access, process, and reply back in a single response. Our approach, called Distributed Lightweight Client Protocol (DLCP), enables LCs to verify with little effort if FNs have agreed on a response. From an experimental evaluation, we observed that DLCP pro- vided lower latency and reduced computing and communication overhead in comparison with the existing conventional approach.

Information Technology (IT) changes are a critical part of the day-to-day operations of most modern organizations, and poor change delivery can pose severe risks to business continuity. In this context, frameworks like COBIT seek to provide guidance for best practices and procedures for proper IT change management, and shareholders often resort to auditing to ensure change delivery following defined procedures. To this end, third-party audit companies perform periodic inspections of the target IT system, log of changes deployed, etc. However, the sheer volume of changes, ever-increasing change complexity, and automation make it challenging to deliver change auditing between inspection events. To tackle this issue, we propose in this paper a blockchain-based approach for continued IT change auditing. In summary, we instrumented a change orchestration framework with a solution for certifying each change deployed in the target system through blockchain. The chain of IT changes in between inspection events is then used to ensure that only certified changes were deployed in the infrastructure.