Zero-knowledge cryptography allows you to post opaque data to the blockchain and selectively reveal properties of it to chosen people and applications.
For example, a zero-knowledge DID can generate a proof to an age-restricted application that you are over 18, without necessarily revealing your birthdate or any other information about yourself.
And this is already covered by the DID/VC W3C specs that don’t need a blockchain. An age restriction in particular will _always require the blessing of a central party_.
