Security Analysis of a Blockchain Network

Abstract

Blockchains have gained popularity due to their versatility and wide range of application. Blockchains are a decentralized data structure guaranteeing integrity and non-repudiation of data We use this to secure provenance meta-data. A blockchain can be seen as a distributed database, or a public ledger of transactions or digital events that have occurred and have been shared among participating parties. A consensus is required to verify each transaction. Blockchains are finding use in cryptocurrencies, academics, clinical trials, healthcare and agriculture. However, like other networks, we need to verify the robustness and availability of the blockchain networks. In this thesis, we leverage existing Denial of Service and Distributed Denial of Service [D/DoS] attacks as a tool to evaluate our proposed blockchain technology, Scrybe, for robustness. First, we check its performance in presence of Transmission Control Protocol [TCP]- based flooding attacks such as SYN Flooding and its variants. We also optimize TCP kernel parameters to improve the utility of syn cookies as a measure against SYN floods. Second, we evaluate malicious miner attempts to exclude client transactions by stalling the mining process and verify that consensus is reached as long as there is at least one honest miner in the network. The underlying algorithm of Scrybe is our novel Lightweight Mining [LWM] algorithm. Our technology guarantees the properties of data integrity and non-repudiation with minimal resource requirements. It introduces a way to mine new blocks in the blockchain, which is not a resource hungry Proof-of-Work [PoW] as required in many present-day cryptocurrency applications.