Tokenized

This vault’s exit leaf is a NUMS key that nobody can sign. If the operator is unavailable, holders have no exit path: their virtual outputs cannot be spent, renewed, or exited. See Exit.

A tokenized vault pools deposits and issues each depositor one share token per sat. Holders redeem shares through a proposal that a guardian can veto. The vault is one contract that plays four roles, each its own output: a deposit address, the pool, a withdrawal address, and a staging output. The pool holds the vault’s control token on every spend. The operator lets an asset’s supply grow only when the transaction also spends its control asset, so only a spend of the pool can issue shares. Every path pins how many shares it issues or burns. The prediction market’s vault does this:

contracts/src/market_vault.ark @ c0b063f

  private function keepsCtrl() {
    require(tx.outputs[0].witnessVersion == 1, "vault version");
    require(tx.outputs[0].assets.lookup(ctrlTxid, ctrlGidx) == 1, "ctrl");
    require(tx.outputs[0].assets.length == 1, "vault assets");
  }

  // Locks n * unit sats and mints n YES + n NO.
  function mint(int n) {
    require(n > 0, "n");
    sets(n, n);
    keepsCtrl();
    require(tx.outputs[0].scriptPubKey == tx.input.current.scriptPubKey, "vault moved");
    require(tx.outputs[0].value == tx.input.current.value + n * unit, "collateral");
    require(tx.outputs[0].value <= capValue, "cap");
  }

Deposit

The deposit address names where the shares arrive. It is this contract with kind 0. Anyone sends sats to it, and the first deposit opens the pool. When the payment arrives, one spend consumes the whole output. 330 sats stay on the share output, and the first deposit leaves 330 sats in the pool as its carrier. The rest is one share per sat. A later deposit is another send to the same address. It keeps 330 sats on the new share output, and the rest is one share per sat. The pool keeps the control token and continues. An asset sent to that address cannot move. A share is a token on the script that the deposit address named. One share is one sat above the pool carrier. The share is the claim. The pool does not know the holder’s key, and no spend asks for the holder’s signature. The pool issues shares on the deposit path only and burns them on the disburse path only. A share moves like any other asset, so a claim changes hands without a spend of the pool.

Withdrawal

The holder sends shares to the withdrawal address. The address is the proposal. It is this contract with kind 2. The constructor names the payout scripts and the one split. The output carries 330 sats and exactly that split. For a redemption, that is the holder’s own script. For a pot, it is first, second, and third place. The send is the authorization, and the pool does not ask who sent it.

Staging

The next spend seals the proposal in a staging output. The sats leave the pool, and the shares sit beside them. The shares are not burned yet.

Veto

A guardian can only cancel. The cancel returns the sats to the pool and the shares to the script named in the constructor. The guardian cannot take the sats and cannot change the split.

Disburse

If nobody cancels, the split is paid to the named scripts and the shares burn, one sat per share. Anyone can build this spend, because a covenant needs only the operator’s and the emulator’s signatures. Building the burn is not a vote. The guardian’s veto is the only decision in the script.

Clocks

The contract enforces no deadlines. The application decides when deposits close and how long the guardian has to veto. disburse has no timelock, so anyone can disburse as soon as the staging output exists. A veto window holds only if every party that can build the disburse waits for it.

Contract

The constructor names one share script and one split. kind is 0 for the deposit, 1 for the pool, 2 for the withdrawal, and 3 for staging. A second split is a second vault. shareScript, holderScript, and the payout scripts are 32-byte witness programs. Set guardian and noExitKey before you fund. noExitKey is the BIP341 NUMS point, so nobody can sign the exit. An unused place is 0, place 2 and place 3 pay more than 330 sats, and place 1 also receives the 330 carrier. open and arrive issue the shares, propose seals staging, veto needs the guardian, and disburse pays the split and burns the shares.

tokenized.ark

pragma arkade ^0.1.0;

// One share is one sat above the pool's 330 sat carrier.
// kind: 0 deposit, 1 pool, 2 withdrawal, 3 staging.
// The constructor names one share script and one split.
// noExitKey is the BIP341 NUMS point: 50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0
contract Tokenized(
  bytes32 shareScript,  // witness program that receives the shares
  bytes32 shareTxid,
  int     shareGidx,
  bytes32 ctrlTxid,
  int     ctrlGidx,
  bytes32 holderScript, // witness program: veto returns shares here
  bytes32 payout1,      // witness program, place 1
  bytes32 payout2,
  bytes32 payout3,
  int     amount1,      // sats of backing, place 1
  int     amount2,
  int     amount3,
  pubkey  guardian,
  pubkey  noExitKey,
  int     kind
) {
  const int DUST = 330;

  private function poolScript() {
    require(tx.outputs[0].scriptPubKey == new Tokenized(
      shareScript, shareTxid, shareGidx, ctrlTxid, ctrlGidx,
      holderScript, payout1, payout2, payout3, amount1, amount2, amount3,
      guardian, noExitKey, 1
    ), "pool");
    require(tx.outputs[0].value >= DUST, "pool dust");
    require(tx.outputs[0].assets.lookup(ctrlTxid, ctrlGidx) == 1, "ctrl");
    require(tx.outputs[0].assets.length == 1, "pool assets");
  }

  private function splitOk() {
    require(amount1 > 0, "place 1");
    if (amount2 == 0) {
      require(amount3 == 0, "place 3");
    } else {
      require(amount2 > DUST, "place 2");
      require(amount3 == 0 || amount3 > DUST, "place 3");
    }
  }

  // First deposit. 330 sats carry the share output, 330 carry the pool, and the rest is shares.
  function open() {
    require(kind == 0, "deposit");
    require(tx.numInputs == 1, "one input");
    require(this.activeInputIndex == 0, "deposit input");
    require(tx.inputs[0].assets.length == 0, "sats");
    require(tx.inputs[0].value > DUST + DUST, "dust");
    int added = tx.inputs[0].value - DUST - DUST;
    require(tx.numOutputs == 2, "two outputs");
    poolScript();
    require(tx.outputs[0].value >= added + DUST, "pool sats");
    require(tx.outputs[1].scriptPubKey == shareScript, "shares");
    require(tx.outputs[1].value == DUST, "carrier");
    require(tx.outputs[1].assets.lookup(shareTxid, shareGidx) == added, "one per sat");
    require(tx.outputs[1].assets.length == 1, "share assets");
    let shareGroup = tx.assetGroups.find(shareTxid, shareGidx);
    require(shareGroup.delta == added, "issued");
    require(shareGroup.isFresh, "fresh shares");
    require(shareGroup.controlIs(ctrlTxid, ctrlGidx), "control");
    let ctrlGroup = tx.assetGroups.find(ctrlTxid, ctrlGidx);
    require(ctrlGroup.delta == 1, "ctrl issued");
    require(ctrlGroup.isFresh, "fresh ctrl");
  }

  // A later deposit. The pool already has its carrier, so every sat above 330 is a new share.
  function arrive() {
    require(kind == 0 || kind == 1, "kind");
    require(tx.numInputs == 2, "pool and deposit");
    require(tx.numOutputs == 2, "two outputs");
    if (kind == 0) {
      require(this.activeInputIndex == 1, "deposit input");
    }
    if (kind == 1) {
      require(this.activeInputIndex == 0, "pool input");
    }
    require(tx.inputs[1].scriptPubKey == new Tokenized(
      shareScript, shareTxid, shareGidx, ctrlTxid, ctrlGidx,
      holderScript, payout1, payout2, payout3, amount1, amount2, amount3,
      guardian, noExitKey, 0
    ), "deposit");
    require(tx.inputs[1].assets.length == 0, "sats");
    require(tx.inputs[1].value > DUST, "dust");
    int added = tx.inputs[1].value - DUST;
    require(tx.inputs[0].scriptPubKey == new Tokenized(
      shareScript, shareTxid, shareGidx, ctrlTxid, ctrlGidx,
      holderScript, payout1, payout2, payout3, amount1, amount2, amount3,
      guardian, noExitKey, 1
    ), "pool");
    require(tx.inputs[0].assets.length == 1, "pool assets");
    poolScript();
    require(tx.outputs[0].value >= tx.inputs[0].value + added, "pool sats");
    require(tx.outputs[1].scriptPubKey == shareScript, "shares");
    require(tx.outputs[1].value == DUST, "carrier");
    require(tx.outputs[1].assets.lookup(shareTxid, shareGidx) == added, "one per sat");
    require(tx.outputs[1].assets.length == 1, "share assets");
    let shareGroup = tx.assetGroups.find(shareTxid, shareGidx);
    require(shareGroup.delta == added, "issued");
    require(shareGroup.controlIs(ctrlTxid, ctrlGidx), "control");
    let ctrlGroup = tx.assetGroups.find(ctrlTxid, ctrlGidx);
    require(ctrlGroup.delta == 0, "ctrl supply");
  }

  // The withdrawal output carries 330 sats and exactly the split. Staging holds both.
  function propose() {
    require(kind == 1 || kind == 2, "kind");
    require(tx.numInputs == 2, "pool and withdrawal");
    require(tx.numOutputs == 2, "two outputs");
    if (kind == 1) {
      require(this.activeInputIndex == 0, "pool input");
    }
    if (kind == 2) {
      require(this.activeInputIndex == 1, "withdrawal input");
    }
    splitOk();
    int shares = amount1 + amount2 + amount3;
    require(tx.inputs[0].scriptPubKey == new Tokenized(
      shareScript, shareTxid, shareGidx, ctrlTxid, ctrlGidx,
      holderScript, payout1, payout2, payout3, amount1, amount2, amount3,
      guardian, noExitKey, 1
    ), "pool");
    require(tx.inputs[0].assets.length == 1, "pool assets");
    require(tx.inputs[1].scriptPubKey == new Tokenized(
      shareScript, shareTxid, shareGidx, ctrlTxid, ctrlGidx,
      holderScript, payout1, payout2, payout3, amount1, amount2, amount3,
      guardian, noExitKey, 2
    ), "withdrawal");
    require(tx.inputs[1].value == DUST, "carrier");
    require(tx.inputs[1].assets.lookup(shareTxid, shareGidx) == shares, "shares");
    require(tx.inputs[1].assets.length == 1, "share assets");
    require(tx.inputs[0].value >= shares + DUST, "pool");
    poolScript();
    require(tx.outputs[0].value >= tx.inputs[0].value - shares, "pool sats");
    require(tx.outputs[1].scriptPubKey == new Tokenized(
      shareScript, shareTxid, shareGidx, ctrlTxid, ctrlGidx,
      holderScript, payout1, payout2, payout3, amount1, amount2, amount3,
      guardian, noExitKey, 3
    ), "staging");
    require(tx.outputs[1].value == shares + DUST, "staging sats");
    require(tx.outputs[1].assets.lookup(shareTxid, shareGidx) == shares, "staging shares");
    require(tx.outputs[1].assets.length == 1, "share assets");
    let shareGroup = tx.assetGroups.find(shareTxid, shareGidx);
    require(shareGroup.delta == 0, "share supply");
    require(shareGroup.controlIs(ctrlTxid, ctrlGidx), "control");
    let ctrlGroup = tx.assetGroups.find(ctrlTxid, ctrlGidx);
    require(ctrlGroup.delta == 0, "ctrl supply");
  }

  function veto(signature guardianSig) {
    require(kind == 1 || kind == 3, "kind");
    require(checkSig(guardianSig, guardian), "guardian");
    require(tx.numInputs == 2, "pool and staging");
    require(tx.numOutputs == 2, "two outputs");
    if (kind == 1) {
      require(this.activeInputIndex == 0, "pool input");
    }
    if (kind == 3) {
      require(this.activeInputIndex == 1, "staging input");
    }
    int shares = amount1 + amount2 + amount3;
    require(tx.inputs[0].scriptPubKey == new Tokenized(
      shareScript, shareTxid, shareGidx, ctrlTxid, ctrlGidx,
      holderScript, payout1, payout2, payout3, amount1, amount2, amount3,
      guardian, noExitKey, 1
    ), "pool");
    require(tx.inputs[0].assets.length == 1, "pool assets");
    require(tx.inputs[1].scriptPubKey == new Tokenized(
      shareScript, shareTxid, shareGidx, ctrlTxid, ctrlGidx,
      holderScript, payout1, payout2, payout3, amount1, amount2, amount3,
      guardian, noExitKey, 3
    ), "staging");
    require(tx.inputs[1].assets.lookup(shareTxid, shareGidx) == shares, "shares");
    require(tx.inputs[1].assets.length == 1, "share assets");
    require(tx.inputs[1].value == shares + DUST, "staging sats");
    poolScript();
    require(tx.outputs[0].value >= tx.inputs[0].value + shares, "sats back");
    require(tx.outputs[1].scriptPubKey == holderScript, "holder");
    require(tx.outputs[1].value == DUST, "holder carrier");
    require(tx.outputs[1].assets.lookup(shareTxid, shareGidx) == shares, "shares back");
    require(tx.outputs[1].assets.length == 1, "share assets");
    let shareGroup = tx.assetGroups.find(shareTxid, shareGidx);
    require(shareGroup.delta == 0, "share supply");
    require(shareGroup.controlIs(ctrlTxid, ctrlGidx), "control");
    let ctrlGroup = tx.assetGroups.find(ctrlTxid, ctrlGidx);
    require(ctrlGroup.delta == 0, "ctrl supply");
  }

  function disburse() {
    require(kind == 3, "staging");
    require(tx.numInputs == 1, "one input");
    require(this.activeInputIndex == 0, "staging input");
    splitOk();
    int shares = amount1 + amount2 + amount3;
    require(tx.inputs[0].assets.lookup(shareTxid, shareGidx) == shares, "shares");
    require(tx.inputs[0].assets.length == 1, "share assets");
    require(tx.inputs[0].value == shares + DUST, "carrier");
    let shareGroup = tx.assetGroups.find(shareTxid, shareGidx);
    require(shareGroup.sumOutputs == 0, "not burned");
    require(shareGroup.controlIs(ctrlTxid, ctrlGidx), "control");
    require(tx.outputs[0].scriptPubKey == payout1, "place 1");
    require(tx.outputs[0].value >= amount1 + DUST, "place 1 sats");
    require(tx.outputs[0].assets.length == 0, "sats");
    if (amount2 == 0) {
      require(tx.numOutputs == 1, "one place");
    } else {
      require(tx.outputs[1].scriptPubKey == payout2, "place 2");
      require(tx.outputs[1].value >= amount2, "place 2 sats");
      require(tx.outputs[1].assets.length == 0, "sats");
      if (amount3 == 0) {
        require(tx.numOutputs == 2, "two places");
      } else {
        require(tx.outputs[2].scriptPubKey == payout3, "place 3");
        require(tx.outputs[2].value >= amount3, "place 3 sats");
        require(tx.outputs[2].assets.length == 0, "sats");
        require(tx.numOutputs == 3, "three places");
      }
    }
  }

  function unilateral(signature noExitSig) tapscript {
    require(older(serverExitDelay));
    require(checkSig(noExitSig, noExitKey));
  }
}

arkadec tokenized.ark -o tokenized.json

unilateral is the NUMS exit leaf (Exit).

Understand

Reference

Deposit

Withdrawal

Staging

Veto

Disburse

Clocks

Contract

​Deposit

​Share

​Withdrawal

​Staging

​Veto

​Disburse

​Clocks

​Contract

Deposit

Share

Withdrawal

Staging

Veto

Disburse

Clocks

Contract