Commitment scheme: Difference between revisions

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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.<ref name="Goldreich">[[Oded Goldreich]] (2001). ''[https://web.archive.org/web/20230323175232/https://www.wisdom.weizmann.ac.il/~oded/foc-book.html Foundations of Cryptography]'': Volume 1, Basic Tools. Cambridge University Press. {{ISBN|0-521-79172-3}}.{{rp|224}}</ref> Commitment schemes are designed so that a party cannot change the value or statement after they have committed to it: that is, commitment schemes are ''binding''. Commitment schemes have important applications in a number of [[cryptographic protocol]]s including secure coin flipping, [[zero-knowledge proof]]s, and [[secure computation]].

A way to visualize a commitment scheme is to think of a sender as putting a message in a locked box, and giving the box to a receiver. The message in the box is hidden from the receiver, who cannot open the lock themselves. Since the receiver has the box, the message inside cannot be changed&mdash;merely revealed if the sender chooses to give them the key at some later time.