This whitepaper describes the steps your organisation can take in order to prepare for and handle data breach notifications under the GDPR. Articles 33 and 34 specify the cases in which your organisation has to register a breach, notify it to the supervisory authority or communicate it to the data subject (the natural persons affected by the breach).
EDPB guidelines on processing personal data through blockchains
These guidelines aim to clarify how data protection laws, particularly the GDPR, apply to blockchain systems.