Blockchain is an interesting technology, with different projects developing every day since it first gained its light back in 2008. More and more research finds blockchain useful in several different sectors. One of the sectors being healthcare, specifically for electronic health records (EHR). EHR contains highly sensitive data which is critical to protect and, just in the year 2019, 41,232,527 records were deemed stolen. Blockchain can provide several benefits when it comes to EHR, such as increased security, availability, and privacy, however, it needs to be done correctly. Due to blockchain being a rather novel technology, there is room for improvement when it comes to integrating blockchain with EHR. In this thesis a framework for EHR in the healthcare sector is proposed, using Ethereum based smart contracts together with decentralized off-chain storage using InterPlanetary File System (IPFS) and strong symmetric encryption. The framework secures the records and provides a scalable solution. Furthermore, a discussion and evaluation regarding several security aspects that the framework excels on as well as what the framework could improve on.

This thesis studies the characteristics of data hosted on the interplanetary name system, which is a part of the interplanetary file system. From these records, information such as file names, locations, and sizes, was investigated. Data was collected on the number of peers hosting the records, thereby determining the decentralization of the record on the network. Data on how often content on the network changes, were collected and investigated. In addition to evaluating records, a search engine was prototyped to show how to integrate the data into a system. A large part of the network was crawled and the rate of change was found to be high. Most of the peers were found to host HTML files. Most content identifiers found were hosted by more than one peer. This means that a search engine needs to be able to support text file formats and revisit peers regularly to be up-to-date with the records.