Savings

This savings vault pays a recipient after a date, and a reset key can stop the payment before then. It is two contracts. Savings holds the output. The owner signs stage, and that signature is the authorization. The output moves to SavingsStage. release pays recipientScript once the emulator clock reaches unlockAt. Before that clock, release fails. The reset key signs reset and returns the output to ownerScript. That stops a payment the owner did not mean to authorize. Your first contract builds the simpler one-contract SavingsVault without a reset key. ownerScript and recipientScript are 32-byte witness programs. Spend outputs use pkScript. serverExitDelay is not a parameter. The client binds it (CSV delays).

savings.ark

pragma arkade ^0.1.0;

import "./savings_stage.ark";

// The owner signs. The output moves to SavingsStage with the same parameters.
contract Savings(
  pubkey owner,
  pubkey resetPk,
  bytes32 ownerScript,
  bytes32 recipientScript,
  int unlockAt
) {
  function stage(signature ownerSig) {
    require(tx.numInputs == 1, "one input");
    require(this.activeInputIndex == 0, "this output");
    require(checkSig(ownerSig, owner), "owner");
    require(tx.numOutputs == 1, "one output");
    require(tx.outputs[0].scriptPubKey == new SavingsStage(
      owner, resetPk, ownerScript, recipientScript, unlockAt
    ), "stage");
    require(tx.outputs[0].value >= tx.input.current.value, "value");
  }

  function unilateral(signature ownerSig) tapscript {
    require(older(serverExitDelay));
    require(checkSig(ownerSig, owner));
  }
}

savings_stage.ark

pragma arkade ^0.1.0;

// release pays the recipient after unlockAt. reset returns the output to ownerScript before that.
contract SavingsStage(
  pubkey owner,
  pubkey resetPk,
  bytes32 ownerScript,
  bytes32 recipientScript,
  int unlockAt
) {
  function release() {
    require(tx.numInputs == 1, "one input");
    require(this.activeInputIndex == 0, "this output");
    require(checkTime(unlockAt), "too early");
    require(tx.numOutputs == 1, "one output");
    require(tx.outputs[0].scriptPubKey == recipientScript, "recipient");
    require(tx.outputs[0].value >= tx.input.current.value, "value");
  }

  function reset(signature resetSig) {
    require(tx.numInputs == 1, "one input");
    require(this.activeInputIndex == 0, "this output");
    require(checkSig(resetSig, resetPk), "reset");
    require(!checkTime(unlockAt), "open");
    require(tx.numOutputs == 1, "one output");
    require(tx.outputs[0].scriptPubKey == ownerScript, "owner");
    require(tx.outputs[0].value >= tx.input.current.value, "value");
  }

  function unilateral(signature ownerSig) tapscript {
    require(older(serverExitDelay));
    require(checkSig(ownerSig, owner));
  }
}

arkadec savings.ark -o savings.json
arkadec savings_stage.ark -o savings_stage.json

Constructor

Parameter	Bound as
`owner`	The 32-byte x-only key that signs `stage` and `unilateral`.
`resetPk`	The 32-byte x-only key that signs `reset`.
`ownerScript`	The witness program `reset` pays.
`recipientScript`	The witness program `release` pays.
`unlockAt`	Unix seconds. `release` waits for the emulator clock. `reset` requires the clock to be earlier.

SavingsStage takes the same parameters. stage copies them onto that output.

Functions

Savings.stage spends this output into one SavingsStage output of at least the same value. SavingsStage.release pays recipientScript the output. The emulator clock must be at or past unlockAt. SavingsStage.reset pays ownerScript the output. The reset key signs, and the emulator clock is still before unlockAt. unilateral on each output is the exit if the operator is unavailable: after serverExitDelay, the owner signs.

Understand

Reference

Constructor

Functions

​Constructor

​Functions

Constructor

Functions