Since the publication, in 2009, of the blockchain founding article by Nakamoto [3] more and more solutions rely on this architecture. In the process an increasing number of solution process personal data stored on this type of decentralized database. In this context the property of undeniability (i.e. once data is recorded, it cannot be altered or removed) of such solutions raise questions regarding how to assure compliance to GDPR. The French Data protection authority, the CNIL, received numerous requests from both the public and the private sector regarding blockchain projects and GDPR [1]. She thus addressed the matter in November 2018 through a publication on its website [2].