Table 3.

Assessment of blockchain for data sharing operations.

DATA SHARING
Do you need to store data or state?	YES. As the name suggest, the data sharing block is going to store medical data that need to be shared among the federation.
Do you have immutability or data integrity requirements?	Immutability NO. Medical data may need to be removed from the storage to guarantee the “right to forgotten” ruled out in GDPR, or specific fields may need to be updated as stated in the “right to rectification” (contact information associated to medical data). Integrity YES. Medical data have a strong integrity requirement (also coming from GDPR). In addition, immutability is also a highly desirable property.
Do you have non-repudiation requirements?	NO. Non-repudiation is desirable, but it is not currently a requirement.
Do you need to support multiple writers for the same data?	NO. When dealing with medical data, we are considering a type of data that are produced by a data producer and then become typically read-only (e.g., blood exam reports or X-ray images are produced, and then they can just be accessed in read mode).
Is there a TTP and is it always on-line?	YES. Without loss of generality, we can assume that the HCO that produced the medical is trusted and is always available.
Are writers known and trusted?	YES. Medical data can be produced only by HCOs, and they are assumed to be trusted and known in the federation.

GDPR, General Data Protection Regulation; TTP, trusted third party; HCO, health-care organization.