Multi-Sig Transactions for minting Cardano NFTs

Minting today: like your grandmother and her doilies

If you’ve minted any NFTs on Cardano, then you know what a painful process it can be. It can be slow, stressful, awkward, it oftentimes feels incredibly unfair for many. It usually looks something like this:

You navigate to some screen: Google Doc, Discord channel, or webpage
You’re shown some address that you need to send ADA to
You’re shown an amount of ADA to send to the address
You navigate to your wallet and initiate a send transaction
You paste in the address to send the ADA to
(You double… no, triple… no, quadruple check that you entered the correct address… you still don’t trust that you’ve done it correctly and you try to find any other human that you can find to check the address… just to realize there are no other humans around because it’s 3 AM and everyone you know thinks you’re absolutely insane for waking up at 3 AM to pay $100 for a JPG… but they’re so dumb, you’ll show them when you flip this NFT for 3 ADA less than mint fee)
You enter the ADA amount (about 5% of you will enter “1” instead of the correct ADA amount, thinking that you’re indicating how many NFTs you want… I’ve definitely never done this before)
And now, with sweaty hands and increasing angst, you click the Send button
And 5 minutes? 15 minutes? 12 hours? later you receive the NFT in your wallet

Have you ever in your life purchased something in the same way that you mint NFTs on Cardano? You probably haven’t, but your grandmother has. Those fancy doilies that adorn her 217-year-old antique table… she ordered those from a mail-order catalog using a very similar process:

Browsed catalog, found a badass doily that she couldn’t live without
Wrote down the product number with a paper and pen(remember those?)
Wrote a check(wtf is a check?)
Put the paper and the check into an envelope(“envelope?” he’s definitely just making up words at this point)
Addressed that envelope to the company with the fancy doilies
Sent that envelope through the physical world using the post
Waited weeks or months until one day the doily arrived… and it was in that moment that she became the envy of all her neighbors

Lucky for your grandmother, Amazon is now a thing. And lucky for us, multi-sig transactions are a thing.

Oh, sh*t

We were about 3 weeks away from launching The Hatchery when panic set in. To provide to our community the climactic, tear-jerking, euphoric experience of hatching an egg and seeing their own Derpling right on the screen instantly, we knew we would have to find a new way of minting.

We began building a smart contract. Well, we hired someone(shoutout to

) to build it for us. It was going to be the first SC used for minting on Cardano! We were excited, as was the Derp Birds community!

And then, about 2 weeks from launch, we saw this Tweet from the legendary Alessandro:

I read the Tweet but of course didn’t understand it. So I read it again, and again, and again. I still didn’t get it, but it seemed important and so I sent it to our engineer(Geek) who was immediately intrigued and minutes later giddy with excitement as he informs the team that we’ll not be using the smart contract for The Hatchery…

A couple of weeks and ONLY ONE delay later, The Hatchery launched using this new multi-sig transaction. All of the benefits that Alessandro had outlined in his Tweet were enjoyed by our community as they began hatching their eggs:

It was fast
It was safer for users
There were no unnecessary transaction costs
It was easier(for our community, not for Geek 😇)
There was much less network congestion than there would have otherwise been
No failed transactions
There were 0 refunds for ~7,500 transactions

Why Multi-Sig?

Our Hatchery transactions were more complicated than common minting transactions because we were requiring the user to send an NFT to us and we would send a Derpling NFT back to them based on the Derp Egg NFT that they sent us.

Here is a simplified look at the process of going from Derp Bird to Derpling:

1. User brings a Derp Bird to The Incubator to create an egg(the Derp Bird never leaves the user's wallet)2. Derp Bird DNA passed to the egg3. 2+ weeks later the user brings the egg to The Hatchery4. User sends ready-to-hatch egg to us and receives a Derpling that takes into account the DNA of the father

We needed to be able to handle the Derp Egg <> Derpling swap in a single transaction and we needed it to happen as quickly as possible.

Multi-sig made all of this possible.

To borrow from

’s recent article about Multi-Sig vs. Smart Contracts:

Multisig transactions are useful for any type of asset swap between multiple parties. Here are some examples that can be handled with multisig transactions:

Minting an NFT on demand, where the NFT creator is paid Ada and customer gets the NFT in a single transaction.
Trading one NFT for another NFT in a single transaction.
Trading multiple NFTs and some Ada, for a newly minted NFT.

Accomplishing the swap in a single transaction was the critical piece for Derp Birds, not only is it cheaper, but it’s way faster and helps to reduce network congestion which is becoming increasingly important as more DeFi services are starting to come online for Cardano.

How it works

If the above graphic is confusing, try this:

The user initiates the transaction(button click) and inputs from the frontend are passed to the backend (may not be relevant for every mint but for The Hatchery these inputs were information about the Egg selected to hatch)
Our backend builds the transaction
The user is prompted to sign the transaction through the Nami
The updated(signed) transaction is passed to our backend
The backend validates the updated transaction
Once validated our backend signs the transaction
(a) This is where it gets interesting… because have everything we need we can go ahead and show the user the NFT they just minted instead of waiting for Cardano to process the transaction. (b) We also submit the transaction to Cardano to process
Once Cardano processes the transaction (a) the NFT is delivered to the user’s wallet and (b) the ADA sent from the user is delivered to our wallet

The beauty of this is that multiple parties are able to sign(“multi-sig”) a single transaction, all before it’s even submitted to the blockchain ⚡⚡⚡

The result

To show off just how fast the turn around from egg to Derpling is, here is a quick recording where you can see just how quickly we’re able to show the user’s NFT to them and this is for a more complex interaction where we need to consider multiple inputs.

Now what?

I believe we have a responsibility to be good citizens of Cardano and specifically of the CNFT community. We demanded marketplaces that uses smart contracts, we demanded doxxed teams, we demanded royalties… and now it’s time for us to all push for better minting experiences.

The minting tech is only one part of the overall minting experience but it is a vital piece for us to get right, doing so will improve network congestion and facilitate adoption of CNFTs… and that seems well worth the additional effort to me.

If you’re thinking of launching a project, please reach out to us and we would love to help! Right now we have a few projects lined up who will be using our multi-sig tech but we want to open that up and help more projects launch in a responsible way.

Source: https://medium.com/@Derp_Birds/multi-sig-transactions-for-minting-cardano-nfts-ecf4ed45e305