Page 81 - U4SSC Blockchain for smart sustainable cities

Table 11: Suitability dimensions of blockchain for cities
1. Trust between the users and the entities
2. Third party as a requirement of the system
3. The users of the system are known
4. The need of control of the system by a specific entity
5. Removing the intermediaries
6. Digital assets
7. Permanent record of information
5.4.2.1. Suitability of B4C
8. Contractual relationship
9. Transaction state record
10. Sensitive data
11. Storing volume of non-transactional data
12. Deleting data
13. Writing access
14. High performance for transaction validation
(1) Trust and similar interest between the users and the entities

In general, if there is trust, most of the decision models recommend not considering blockchain as a
top priority application to adopt. If the writers all mutually trust each other, i.e. they assume that no
113
participant is malicious, a database with shared writing access could be considered a better solution. There
is trust among the users in fewer than 50 per cent of the use-cases. The majority of these use-cases have
adopted a private blockchain. Under these conditions, the choice of blockchain might be suitable if the
option of using blockchain is not associated with the need for a trust-free application. This might create an
inconsistency between the rule applied and the actual case. However, the decision could be problematic
and inconsistent with a public blockchain type. This dimension is not a priority in defining the suitability of
blockchain. However, it is critical to determine the type of blockchain to implement. 114

(2) Presence of a third party in the system (TTP)

Blockchain added-value is based on the principle of decentralization. There is no central authority of
control during the transactions. The use of blockchain is not relevant and not suitable if a TTP is needed.
However, 30 per cent of the cases consider its presence necessary. Blockchain is removing the traditional
trusted third-party, however, new third parties are created with new roles. It is critical to understand that
it is a paradigm shift, a different type of system that required various tools for analysis. The parties in the
blockchain need to trust each other otherwise the potential for using blockchain is limited to the use-cases,
which makes it possible to use blockchain and have a third party (i.e. Energy system and Debt relief use-
cases). Consequently, this dimension is not critical for the applicability of blockchain for the city, however
it will define the type of blockchain which is eventually chosen.

U4SSC: Blockchain for smart sustainable cities 71