A number of key mechanisms are used in blockchain implementations, most notably key-pairs and hash functions (Badev and Chen, 2017, Bohme et al., The technology can therefore be regarded as a high security technology, but not without vulnerabilities. While the decentralised network is relatively safe from serious hacking attacks due to its set-up, an insecure storage of private keys might enable hackers to gain access to sensitive data. In addition, all interfaces to systems outside the blockchain environment are potentially targets for hacker attacks, if not properly secured.