The blockchain is a technology a personal data processing can
rely on. Its very specific characteristics raise difficulties for
the implementation of the obligations imposed by the General Data
Protection Regulation (GDPR).
On September 24, 2018, the CNIL (The French Data Protection
Authority) issued its first analysis and recommendations for those
who wish to use the blockchain when they process personal
data.
The blockchain constitutes a "method for recording
continuously generated data, in the form of blocks that are linked
to each other in chronological order of validation, each block and
its sequence being protected against
changes"1.
It is in particular used for the cryptocurrency for which it is
a sort of public register of the transactions, like the bitcoin,
which is far from being the only cryptocurrency. The use of the
blockchain can rely on so-called "smart contracts" which
are computer programs which are self-executing: "if" the
program notes that a
