One definition is that of a long list of transactions (or ledger) that is kept on lots of different computers (distributed) .  The contents are verifiable and because of the multiplicity of copies, very difficult to deny or change something that has been recorded as it would involve editing all the subsequent transactions or blocks.

  • A blockchain may be public or private
  • Needs more than 50% of participants to have any chance of altering a blockchain
  • The blockchain holds it’s entire history

Double Spending

With digital copies can be easily be reproduced and in the case of money you would only want it spend once otherwise you are in the position of creating counterfeit currency.  A blockchain can record each digital copy seperately and keep it unique.

Blockchains create issues:

  • Personal data is open to view
  • Cannot delete or change (GDPR right to be forgotten)
  • No person can be identified as a Data Controller
  • Data is stored in multiple countries so not possible to determine which data laws are in force.
  • Can any blockchain data really classed as personal or is it automatically public domain.

Crypto Currencies

Practical and Commercial uses for blockchain