Often a creator will want to distribute the NFTs they've created in a pseudo-random way with little interaction from the receiver. This processes is made more difficult because a receiver needs to opt into the ASA ahead of time and it can be diffuclt to coordinate which ASA id they'd need to opt into.

This repository demonstrates the use of a Smart Signature acting as an escrow to hold an NFT and ed25519 signature validation allow the holder of a secret key to claim the NFT.

Can be used in conjunction with the Decipher Tickets front end for a full solution

Why not just use a password and compare with pre-image of the hash of the password?

If the transaction was submitted to a malicious node, that node may not forward the transaction but instead capture the password and create a transaction to claim the NFT on its behalf. By using an ed25519 keypair and signing the transaction id, a malicious node cannot produce a transaction that will pass the ed25519 verification.

Some number of Escrow accounts are created and funded with algos and an NFT. Each escrow account has a hardcoded, unique, ed25519 public key. During the claim processes the public key is used to allow any account passing a valid, matching, ed25519 signature of the claim transaction id to claim the NFT.

In order to claim the NFT, the user is passed the secret key (or password, salt and key generation parameters to reproduce the key) for the relevant escrow account. The key is then used to sign the transaction id of the second transaction in the the atomic group and the signature is passed as the 0th argument.

The contract validates that the signature passed is a valid for the public key it has hardcoded and approves the transaction.

In this demo there is also the concept of a "recover" transaction which will allow the funding account to reclaim any unclaimed NFTs.

Three operations against the Escrow logic are allowed:

1. Fund: payment from seeder, escrow opt in to NFT, seeder xfer nft to escrow

2. Claim: claimer opts in to NFT, escrow close NFT to claimer, escrow close algos to seeder

3. Recover: escrow close NFT to seeder, escrow close algos to seeder, seeder dummy payment to act as "cosign"

escrow.py - contains PyTEAL logic to generate template contract

fund.py - Functions to create escrow and send initial seed group txns from seeder

claim.py - Functions to simulate what a claimer will need to send to claim the NFT

recover.py - Functions to simulate what the seeder will need to send to recover any unclaimed NFTs

nftcreate.py - Functions to create NFTs to place in escrow

demo.py - Python logic to run e2e to simulate NFTs creation, escrow NFT and algo funding, run NFT claim txns, recover unclaimed NFTs

util.py - Some utility related functions that are used in multiple places

clone sandbox and run:

cd sandbox && ./sandbox up dev

cd to this repo and run:

python demo.py -h

usage: demo.py [-h] [-count COUNT] [-create] [-fund] [-claim] [-recover]

optional arguments:
  -h, --help    show this help message and exit
  -count COUNT  Number of NFTs to create
  -create       Create Set of NFTs
  -fund         Send Algos and NFT to escrow accounts
  -claim        Create accounts and attempt to claim nfts from escrows
  -recover      Use the seeder account to recover nft from escrow

to run through the full demo

python demo.py -count 10 -create -fund -claim -recover