There is an everlasting arms race between censoring bodies and those in its grip. When the censor is employing increasingly sophisticated techniques to digitally monitor and restrict those in its scope, equally sophisticated means to circumvent the digital repression come forward. Those suffering under digital censorship are using nifty ways to escape the censor's grip. Digitally restrictive regimes occasionally still allow access to blockchain applications such as cryptocurrencies, albeit in limited form. Blockchains often enjoy a global nature, but traditional and well established cryptocurrencies such as Bitcoin often do not have high performance. Second layer solutions, also known as off-chain solutions, offer a network of payment channels where transactions can be completed in peer-to-peer fashion with little interaction with the slow blockchain. In this thesis we investigate how Bitcoin's off-chain solution, the Lightning Network, can be employed to circumvent digital censorship. We introduce Periscope, a protocol that allows for tunneling of internet traffic between two hosts over a stream of micro-transactions embedded with data. Next, we thoroughly analyse its security and the network's suitability from a theoretical perspective. Following this, an empirical evaluation study is done to get an understanding of the performance of the protocol under various circumstances. We hope that Periscope serves as an additional mean to access the free internet to those in need.

Bitcoin’s underlying consensus algorithm, Proof of Work, is of inefficient nature. Due to the sheer size that Bitcoin has grown to over the recent years, power consumption has increased so much that the Bitcoin network has been estimated to consume more power than the whole country of Ireland. This paper investigates several alternatives to the Proof of Work consensus algorithm, with a focus on energy efficiency. We found permissioned and permissionless consensus algorithms that offer solutions that consume significantly less energy than Proof of Work.

There is a lot involved in providing a loan as a company, mostly in terms of legalities and risk management. As a lender it is important to have a clear record of the customers applying for a loan, as this helps assessing the risk that comes with providing a loan. Furthermore, it is required by law to know who it is that you are providing a loan to. To achieve this, loan providers gather a variety of personal and financial information. The gathering of such information has traditionally been a time consuming practice, both for the customer and the lender. The customer is required to manually find and submit information, and in turn the lender has to verify that the received information is not fraudulent or incorrect. If collection of personal information, payrolls and credits could be done in an automated way, both the customer and the lender will benefit greatly. We have designed and developed the Customer Verification Engine, the CVE, in order to solve this time consuming process of collecting and submitting documents. The CVE is capable of cleverly combining several external data sources, creating a clear record of the customer. While previously the customer had to manually provide a large set of documents, it is now done at the push of a button. Furthermore, by having a system where the information is retrieved, rather than provided by the customer, the verification becomes significantly more reliable, as there is little to no room for the customer to provide fraudulent information. The CVE is a robust and scalable system that is capable of handling unexpected behavior both in terms of input and connection to external sources. An extensive test suite verifies correct behavior of the CVE under both normal and unexpected circumstances. The information gathered by the CVE will be relied upon to determine whether or not a customer is eligible for a loan. As the CVE will be continued to be worked upon, we have put effort into making it extendable for future developers. Using the extensive documentation and the modularity of the system, it should be straightforward for future developers to add new integrations with external parties to the CVE.