context: https://twitter.com/mHaGqnOACyFm0h5/status/1195531541373423619

pay_to_hash_multisig.ivy

// PoC for 2-of-3 multisig where one of the keys is an opendime (sealed at time of scriptPubKey creation)
// see on https://ivy-lang.org/bitcoin
// the script ivy generates seems sub-optimal (some unconditional rotation and rolling of stack elements)
// but this is just a yucky PoC, and the ivy source is arguably easier to understand anyway

contract LockWithKeyHashMultisig(
  pubKey1: PublicKey,
  pubKey2: PublicKey,
  pubKey3hash: Ripemd160(Sha256(PublicKey)), // opendime address
  dummyKey: PublicKey, // should be a curve point with no known discrete log
  val: Value
) {
  // this path can spends with the opendime key which must be provided in the scriptSig much like p2pkh
  // (the 2 signatures can still correspond to pubKey1 and pubKey2)
  clause spendHash(sig1: Signature, sig2: Signature, pubKey3: PublicKey) {
    verify ripemd160(sha256(pubKey3)) == pubKey3hash
    verify checkMultiSig([pubKey1, pubKey2, pubKey3], [sig1, sig2])
    unlock val
  }

  // this path can only spend from pubKey1 and pubKey2 if the dummy key really is unusable
  clause spend(sig1: Signature, sig2: Signature) {
    verify checkMultiSig([pubKey1, pubKey2, dummyKey], [sig1, sig2])
    unlock val
  }
}