Add part about blockchain

thesis/content/05-proof-of-concept/technology-decisions.tex

@@ -42,6 +42,11 @@ In the following, various \ac{P2P} networks are considered and examined for thei
 \subsubsection{Filesharing \ac{P2P} Networks}
 
 \subsubsection{Blockchain}
+\label{sec:blockchain}
+In a blockchain, the private data of the users could be stored encrypted and shared with other users. The corresponding smart contracts would have to be designed for this purpose. Regardless of the blockchain, executing the smart contracts to store the data, however, consumes a token. The user has to get the tokens beforehand and deposit them in his wallet. To avoid this, a test network (e.g., Rinkeby at Ethereum) could be used. A test network would have the advantage that tokens could be made available to the user free of charge and that the execution of the smart contracts would thus also be free of charge. However, test networks are used to test new software updates and usually do not offer the same security as the main network. They should only be used to test applications before releasing them to the main net. In order to protect against abuse, token requests are usually limited and take a while until they arrive in the user's wallet. Besides, it is often required to post specific content in a social network or to perform another task.
+
+A solution based on a blockchain increases complexity for the user. Since the hybrid solution was required to keep the complexity and additional effort as low as possible, such a solution using a blockchain was categorically excluded.
+
 
 \subsubsection{\ac{IPFS}}
 \label{sec:ipfs}