Commitments

In a commitment scheme, Alice can commit to a value to obtain a commitment . At some point later, Bob would like for Alice to reveal the committed value behind , and show that indeed Alice was the one that had committed in the first place.

A rough informal sketch of this interaction can be shown as:

AliceBob[x] := Commit(x)sometime laterim convinced.[x]show me!xAliceBob

A cryptographic commitment scheme has two notable properties:

  • Hiding: A commitment should reveal nothing about the underlying .
  • Binding: A commitment , should only be revealed to , i.e. for some we shouldn't be able to compute a commitment .