pragma cashscript ^0.13.0;

// CommitBox — the "commit" of a commit–reveal takeover
// (Decentralized.DNS/DESIGN-covenant-registry.md §6.3).
//
// A taker creates one of these a block or more BEFORE taking a name over. Its
// address reveals nothing: commitHash = hash256(name ‖ salt). The registry
// covenant rebuilds this script from the taker's key hash and the revealed
// salt, and requires input 1 of the takeover to be locked to it.
//
// The box enforces its own age (this.age), so a takeover cannot be assembled in
// the same block as its commit, and it needs the taker's signature, so nobody
// else can spend it out from under them.
//
// STATUS: chipnet draft, NOT REVIEWED — see name-registry.cash.
contract CommitBox(bytes32 commitHash, bytes20 ownerPkh) {
    function spend(pubkey pk, sig s) {
        require(hash160(pk) == ownerPkh);
        require(checkSig(s, pk));
        require(this.age >= 1);
        // The commitment is data, not logic: it only has to be part of this
        // script so that it is part of the address. (The compiler rejects an
        // unused constructor argument.)
        require(commitHash.length == 32);
    }
}