Held deposit - Zceipt

A desk is holding a deposit you made from shielded ZEC and asks where it came from, or that it was you. A viewing key shows them every payment your wallet ever made or received. A receipt shows this one deposit and, if you choose, where its money came from and an address you control.

What to send

Make the proofs with the viewing key on an online machine, then sign where the seed is:

zceipt create --ufvk @viewing-key.txt --birthday <wallet birthday> --txid <deposit txid> \
  --prove-source --reveal-source-value \
  --prove-address <an address the desk knows> \
  -m "Deposit for account 7731" --unsigned deposit.prepared
zceipt sign deposit.prepared --seed-stdin

sign shows everything the receipt reveals and asks before signing. If the desk gave you a request link, add --request '<link>' so the receipt answers that request and can’t be reused.

Option	The desk learns	Leave out if
(always)	Your spend authority made this payment; recipient, amount, memo
`--prove-source`	Which earlier output created each spent note	The desk doesn’t ask
`--reveal-source-value`	Each spent note’s exact value	You only need the link
`--prove-address`	The same spend authority controls an address you name	You don’t want deposit and address linked
`--refund-to`	A refund address only you could have chosen

It never shows your balance, other notes or transactions, or your viewing key.

For the desk

A desk screens the funding with a screened set: it publishes the commitments of outputs it has vetted, and the payer proves the deposit came from that list without saying which. For a two-step ZIP 320 TEX deposit, --tex-deposit and --second-tx prove who made it.

Before you send

A receipt is evidence you give for one deposit, not a standing permission. Nothing here runs without you.
--prove-source lets the desk tie this deposit to the transaction that funded it. Send it only to the desk that asked.
It is a bearer proof. A receipt that answers the desk’s request is useless to anyone else.