How blockchain impacts cloud-based system performance: a case study for a groupware communication application

This paper examines the performance trade-off when implementing a blockchain architecture for a cloud-based groupware communication application. We measure the additional cloud-based resources and performance costs of the overhead required to implement a groupware collaboration system over a blockchain architecture. To evaluate our groupware application, we develop measuring instruments for testing scalability and performance of computer systems deployed as cloud computing applications. While some details of our groupware collaboration application have been published in earlier work, in this paper we reflect on a generalized measuring method for blockchain-enabled applications which may in turn lead to a general methodology for testing cloud-based system performance and scalability using blockchain. Response time and transaction throughput metrics are collected for the blockchain implementation against the non-blockchain implementation and some conclusions are drawn about the additional resources that a blockchain architecture for a groupware collaboration application impose

Implementing TontineCoin

One of the alternatives to proof-of-work (PoW) consensus protocols is proof-of- stake (PoS) protocols, which address its energy and cost related issues. But they suffer from the nothing-at-stake problem; validators (PoS miners) are bound to lose nothing if they support multiple blockchain forks. Tendermint, a PoS protocol, handles this problem by forcing validators to bond their stake and then seizing a cheater’s stake when caught signing multiple competing blocks. The seized stake is then evenly distributed amongst the rest of validators. However, as the number of validators increases, the benefit in finding a cheater compared to the cost of monitoring validators reduces, weakening the system’s defense against the problem. Previous work on TontineCoin addresses this problem by utilizing the concept of tontines. A tontine is an investment scheme in which each participant receives a portion of benefits based on their share. As the number of participants in a tontine decreases, individual benefit increases, which acts as a motivation for participants to eliminate each other. Utilizing this feature in TontineCoin ensures that validators (participants of a tontine) are highly motivated to monitor each other, thus strengthening the system against the nothing-at-stake problem. This project implements a prototype of Tendermint using the Spartan Gold codebase and develops TontineCoin based on it. This implementation is the first implementation of the protocol, and simulates and contrasts five different normal operations in both the Tendermint and TontineCoin models. It also simulates and discusses how a nothing-at-stake attack is handled in TontineCoin compared to Tendermint

BLOCKGRID: A BLOCKCHAIN-MEDIATED CYBER-PHYSICAL INSTRUCTIONAL PLATFORM

Includes supplementary material, which may be found at https://calhoun.nps.edu/handle/10945/66767Blockchain technology has garnered significant attention for its disruptive potential in several domains of national security interest. For the United States government to meet the challenge of incorporating blockchain technology into its IT infrastructure and cyber warfare strategy, personnel must be educated about blockchain technology and its applications. This thesis presents both the design and prototype implementation for a blockchain-mediated cyber-physical system called a BlockGrid. The system consists of a cluster of microcomputers that form a simple smart grid controlled by smart contracts on a private blockchain. The microcomputers act as private blockchain nodes and are programmed to activate microcomputer-attached circuits in response to smart-contract transactions. LEDs are used as visible circuit elements that serve as indicators of the blockchain’s activity and allow demonstration of the technology to observers. Innovations in networking configuration and physical layout allow the prototype to be highly portable and pre-configured for use upon assembly. Implementation options allow the use of BlockGrid in a variety of instructional settings, thus increasing its potential benefit to educators.Civilian, CyberCorps: Scholarship for ServiceApproved for public release. distribution is unlimite