NFT spec

When Asteroid Protocol initially launched, there was no way to create collections or to combine specific inscriptions/NFTs into groups. This changed with the launch of NFT collections on March 28, 2024. NFT collections use the following specification:

Specification requirements

• Easy to identify which collection any given NFT belongs to

• Possible to find all NFTs that belong to a given collection

• Collection metadata such as its name, description, and image

• NFT metadata such as name, description, image, and traits

• Open collection - not all collection NFTs have to be known/minted when creating a collection

• Backwards compatible with existing inscriptions

NFTs in Asteroid Context

Asteroid protocol already supports arbitrary data inscription with an option to specify a parent and metadata like name, description and mime type (media type of inscribed content)

Let’s define Generic inscription transaction specification to see all the details of what’s available.

Generic Inscription transaction

Inscription transaction MUST specify Inscription operation, optionally CAN provide Inscription data, and optionally CAN require Inscription fee to be paid

Example inscription operation:

urn:{metaprotocol}:{chain-id}@{version};{operation}${param}={value},{param}={value}

Key	Description	Example
metaprotocol	A protocol identifier	inscription
chain-id	The chain ID for the Cosmos Hub	cosmoshub-4
version	The current version	v1
operation	A protocol operation	inscribe
param(s)	Operation params	h=hash

---

Inscription data:

Key	Description	Example
Parent	Link to the parent	An account address, collection address
Metadata	Inscription metadata	{ “name": "asteroid", "description": "asteroid", "mime": "image/png" }
Content	Base64 encoded data content	Image, Audio, Text file

---

Inscription fee:

Key	Description
Receiver	Fee receiver account address
Denom	Token denomination
Amount	Token amount
IBC Channel	Optional IBC channel

Create a new Inscription transaction

Inscription operation:

urn:inscription:{chain-id}@v1;inscribe$h={hash}

Key	Value	Description
chain-id	cosmoshub-4	The chain ID for the Cosmos Hub
version	v1	The current version
operation	inscribe	Inscribe new content

---

Params:

Param	Description	Restrictions
h	The hash of the content being inscribed	Must be SHA-256(base64(JSON metadata) + base64(content))

---

Inscription data:

Key	Value	Description
Parent	An account address	Link to the parent
Metadata	See https://www.notion.so/7cb113ce40dd44afb695b0e1a9340e9b?pvs=21	Inscription metadata
Content	Image, Audio, Text file	The actual base64 encoded content

---

Metadata:

Key	Description	Restrictions
Name	Inscription name
Description	Inscription description
Mime	The media type of inscribed content
Explicit content	Explicit content flag (currently not in spec, but I would propose to add it so it could be checked when uploading the image and creating the inscribe transaction)	true/false
Attributes	List of Inscription traits (see below)

Inscriptions also support custom "attributes” which can be displayed alongside your artwork. This allows for unique features including rarity traits for collections.

To generate attributes, include them as an array within your metadata:

...
{
"attributes": [
    {
      "trait_type": "Base",
      "value": "Starfish"
    },
    {
      "trait_type": "Eyes",
      "value": "Big"
    },
    {
      "trait_type": "Mouth",
      "value": "Surprised"
    },
    {
      "trait_type": "Level",
      "value": 5
    },
    {
      "trait_type": "Stamina",
      "value": 1.4
    },
    {
      "trait_type": "Personality",
      "value": "Sad"
    },
    {
      "display_type": "boost_number",
      "trait_type": "Aqua Power",
      "value": 40
    },
    {
      "display_type": "boost_percentage",
      "trait_type": "Stamina Increase",
      "value": 10
    },
    {
      "display_type": "number",
      "trait_type": "Generation",
      "value": 2
    }
  ]
}

Here trait_type is the name of the trait, value is the value of the trait, and display_type is an optional field indicating how you would like it to be displayed. For string traits, you don't have to worry about display_type.

Collections

Collections enable NFTs to be grouped together and for that information to be verified on-chain. Additionally, it makes it easier to manage these collections by allocating data for them on-chain

To group NFTs, we must first create a Collection NFT whose purpose is to store any metadata related to that collection. A collection is itself, an NFT.

Inscription data / Metadata:

Key	Description	Restrictions
Symbol	Collection symbol (i.e. BAYC could be the symbol for Bored Ape Yacht Club)	Must be unique
Name	Collection name	Must be unique
Description	Collection description
Mime	The media type of the inscribed collection logo
Explicit content	Explicit content flag
Royalty percentage	Optional royalty. Defaults to creator address or user can specify an overriding payment address. Enforcement happens on marketplace level (marketplaces should honor the creator’s intent).
Payment address	Optional royalty payment address
Minter	Optional minter address, when minter is different from the creator (for example when minting is done by off-chain service)
Twitter	Optional Twitter URL	https://twitter.com/handle
Discord	Optional Discord URL	https://discord.com/invite/channel_name
Website	Optional Website URL
Telegram	Optional Telegram URL	https://t.me/channel_name

Associating and Verifying Collection NFTs

To associate NFT with collection we set NFT Inscription data / Parent to Collection transaction hash

Indexer must verify if NFT is a valid part of the collection since anyone can set the Inscription data / Parent and pretend their NFT to be part of any collection

NFT is a valid part of the Collection when one of the following conditions is true:

• Inscribed by the Collection owner

• Contains signature signed with Collection minter private key (details TBD)

Backwards compatibility and Migration of existing inscriptions

• All new inscriptions will be inscribed with V2 version

• There would be a new operation to perform migration (migrate)

• Migration operation is allowed only once

• We support v1, migration is optional

• Anyone could migrate their inscription to v2 and change parent to collection or/and add additional metadata like traits

Updates

1. Add a way to do mass migrations (i.e. how can I update traits for 100 pre-existing NFTs?)

2. Updating traits on legacy NFTs can only be done once via migration. Only the creator can do it.

3. Add to front-end a checkbox that says: “I own the rights to publish this image.”

4. This model would support packs (a collection would have pack subcollections). “Opening the pack” would be at the moment of minting. Or we could explore having the packs on-chain.

Rarity score

Rarity score for a trait = 1 / number of NFTs with the trait value / total number of nfts in the collection Rarity score for a nft = sum of rarity scores of all of its trait value

Math representation: