Commitment Scheme

What is Commitment Scheme?

A commitment scheme is a cryptographic technique that allows one party to "commit" to a value while keeping it hidden from others, with the ability to "reveal" it later to prove it was the original choice.

How does Commitment Scheme work?

1. Commit Phase: The user picks a value (e.g., a vote) and a secret random number ("salt"). They send a hash of these items to the network.
2. Hiding: No one can see the original value just by looking at the hash.
3. Binding: The user cannot change the value because a different value would result in a different hash.
4. Reveal Phase: Later, the user shares the original value and the salt.
5. Verify: Anyone can re-hash the revealed data to see if it matches the original commitment.

Why does Commitment Scheme matter?

It is essential for ensuring fairness in decentralized applications. It is used in "sealed-bid" auctions, secret voting systems, and for generating verifiable on-chain randomness (to prevent participants from "gaming" the outcome).

Key features of Commitment Scheme

• Hiding (the value is secret until revealed)
• Binding (the value cannot be changed)
• Cryptographically secure
• Essential for fair "reveal" mechanics
• Foundation for many privacy-preserving protocols

Examples of Commitment Scheme

• A DAO vote where everyone commits their vote first, then all votes are revealed at once.
• A "Commit-Reveal" random number generator used in an on-chain game.
• Using a "Merkle Root" as a commitment to a large list of data (like an airdrop whitelist).