 The main idea behind blockchain technology was first described in the seminal paper on Bitcoins (Nakamoto, n.d., Other Internet Resources). A blockchain is basically a distributed ledger that stores transactions in a non-reputable way, without the use of a trusted third party. Cryptography is used to ensure that all transactions are “approved” by members of the blockchain and stored in such a way that they are linked to previous transactions and cannot be removed. Although focused on data integrity and not inherently anonymous, blockchain technology enables many privacy-related applications (Yli-Huumo et al. 2016, Karame and Capkun 2018), such as anonymous cryptocurrency (Narayanan et al. 2016) and self-sovereign identity (see below).