Information Security
Updated Sun, 02 Oct 2022 06:28:18 GMT

What is the name of this concept involving hashes?

I'm looking for the name of a concept that works as follows:

  1. I post a hash of a file publically e.g. on Twitter
  2. Whenever needed, I provide the file with the contents that make up the given hash

The purpose is maybe to proof ownership or otherwise proof that something was known to me in the past before it became public.

Knowing the name will enable me reading more about it.


To me this sounds like a commitment scheme:

A commitment scheme is a cryptographic primitive that allows one to commit to a chosen value (or chosen statement) while keeping it hidden to others, with the ability to reveal the committed value later


Interactions in a commitment scheme take place in two phases:

  1. the commit phase during which a value is chosen and committed to
  2. the reveal phase during which the value is revealed by the sender, then the receiver verifies its authenticity

You can see this term being used by several of the answers to this question, for example.