Paying a Multi-Receiver UA

Multi-Receivers UA are addresses that combine two or more types of addresses. For example a Transparent and a Sapling, or a Transparent, a Sapling and an Orchard address.

Multi-Receivers UAs present a new challenge to the wallet because they allow the transaction algorithm to choose between two or more addresses.

Most wallets systematically choose the highest pool they support, but better solutions may exist.

Consider a situation where the wallet has the following balance:

transparent: 200000000, sapling: 300000000, orchard: 124950000

Let's suppose we are paying 2.5 ZEC to a full receiver UA. What do you think the wallet should do?

It would not have enough Orchard funds available if it were hard-wired to deliver to the Orchard receiver.

However, by picking the Sapling receiver, the transaction achieves the highest privacy since our Sapling balance can cover the required amount.

zcash-warp〉pay 1 uregtest1chggrm62vhkf5ftv3mawjvavuwjgx7x3wj582tlq5769cl6xf6q6whrukc5z2mxyz603j6lzda8pgyy8dy59qta58uncp6cetwmweklawr2ty34jqw6e8d704rly7m7eh9wcs50m0hdvsdg5akzys3uh95wugw9n78a5gj0mc0m69rsu2lf32tl8glje9p6870e9wwy6qeeyvg6x7ae 7 250000000 7 1 1

json

{
  "height": 103,
  "recipients": [
    {
      "address": "zregtestsapling1h0ud99tf3qe9lmpmncs8rz0vwluhav0etuuejmvxcjnykd6gvp8tllh77ac0dm60zqmyq3c2a3t",
      "amount": 250000000,
      "change": false
    },
    {
      "address": "zregtestsapling1h0ud99tf3qe9lmpmncs8rz0vwluhav0etuuejmvxcjnykd6gvp8tllh77ac0dm60zqmyq3c2a3t",
      "amount": 49985000,
      "change": true
    }
  ],
  "transparent_ins": 0,
  "sapling_net": 15000,
  "orchard_net": 0,
  "fee": 15000,
  "privacy_level": 3,
  "num_inputs": [
    0,
    3,
    0
  ],
  "num_outputs": [
    0,
    2,
    0
  ],
  "data": null,
  "keys": null
}

As we can see from the transaction report, the wallet opted to use Sapling notes.

TIP

Feel free to experiment with a combination of receivers. What do you think the wallet should do in each situation? Does it match your expectations?

The wallet follows a few ground rules:

Shielded funds are preferable to transparent funds.
If a recipient indicates a single shielded receiver address, the wallet will try to use funds from the same pool.
We will never send to a transparent receiver of a UA.

They are other rules but they are more flexible.

Next, we'll use payment URI in place of the JSON object.

Paying a Multi-Receiver UA ​

Paying a Multi-Receiver UA