Use Cases

Blockchains solve a very narrow range of problems related to trust, but they do so in a revolutionary powerful way. Never before have mutually-distrustful parties spread across the world been able to agree on a common set of truths for which they have significant incentive to declare false. While blockchains won’t drive your car, schedule your toast machine based on your sleep patterns, or make large files easier to send over email, they provide a powerful toolkit that can provide a number of novel functionalities which used to be only possible by engaging with at least one trusted party.

The solutions blockchains provide aren’t just mental exercises for purist geeks either–they eliminate vulnerabilities in our current socioeconomic system that have been exploited before: overprinting of fiat, criminal evidence manipulation, lottery cheating, stolen intellectual property, fake pieces of art, cryptography with backdoors built in, and more.

I’ve reproduced the (incomplete) list on the front page for use cases of blockchains here for convenience:

  • Mediating between mutually-exclusive events to ensure only one occurs
    • A property is only owned by one party
    • There is only one Mona Lisa, and the owner is known
    • The same money wasn’t simultaneously spent at two stores
  • Proving to multiple parties that they all received the same information
    • Lottery results
    • Medical history
    • Stock predictions
  • Executing contracts automatically and without counterparty risk
    • Hedging against currency volatility
    • Payouts of lottery winnings and bets
    • Guaranteed payment of dividends or payroll on a certain schedule
  • Trustlessly engaging in trade
    • Incentive-compatible escrow
    • Trading blockchain tokens between distrustful parties
    • Irrefutable proof that a payment was (or was not) sent
  • Synchronizing identity
    • Man-in-the-middle resistance
    • Decentralized domain registration and update
    • Irrefutable association between existing identity and additional information (a new public key, a new email address, etc.)
  • Protecting identity
    • Logging in without sending (or having) a password
    • Selectively providing probably-correct information
    • No need for many services to store private information
  • Resisting censorship
    • Provably-fair voting
    • Proving membership of a group without revealing which member you are
    • Publishing small pieces of a data in a way no government agency can remove
  • Proving something happened before a certain time
    • Invention of a new idea
    • Completion of a particular task
    • Taking a photo or video of a crime scene
  • Proving something happened at or after a certain time
    • Goods were fresh when delivered
    • Funds or property weren’t prematurely transferred
  • Proving that data has been unaltered since a certain time
    • Evidence wasn’t manipulated
    • Software wasn’t tampered with
  • Providing public tamper-proof random numbers
    • Provably-fair gambling
    • Nothing-up-my-sleeve numbers to protect against backdoors in cryptography
  • Preventing certain activities (or proving to what extent they occurred and who performed them)
    • Pyramid schemes
    • Naked short selling
    • Anonymous currency exchange
    • Fractional reserve and currency mintage

This section of the website provides the implementation details behind many of these solutions, and provides what I believe to be best-practices for using blockchains to achieve a particular goal.