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NFT Introduction

About This Document​

Rather than simply copy what other blockchains had already done, we modeled our NFT standard after the traditional art world. Art is far from the only use case for Chia NFTs, but it was our starting point nonetheless.

This document will guide you through the process of creating DIDs that conform to Chia's DID standard, as well as minting NFTs that adhere to Chia's NFT standard. It will demonstrate this functionality using both the command-line and RPCs on Windows, MacOS and Linux. It will also show you how to verify that your NFTs are working as designed in Chia's reference wallet. We'll use the testnet for most of this guide, but we'll also give you some tips on deploying NFTs on Chia's mainnet.

For detailed instructions on running each of the commands from this tutorial, see:

For more documentation about Chia NFTs and DIDs, see:

Key features​

Chia NFTs focus on three key features:

  • Marketplace Independence -- you never are required to transfer your NFT to a marketplace in order to sell it. While marketplace custody is allowed, self custody has been standard with Chia NFTs from Day 1.
  • Consistent Provenance -- DIDs enable the tracking of an NFT's complete history. You are highly encouraged to attach your DID to all of the NFTs you create. The DID will later be used to verify the NFTs' authenticity.
  • Digital Permanence -- You can add a list of links to your NFTs' data, metadata, and license. Each link is verified with a hash, which is permanently embedded in the NFT itself. If one link changes or disappears, you can rely on another existing link, or create a new one. Even if all of the links disappear, as long as someone maintains a copy of the original file, the owner can always prepend a new link to the list.

Collections​

While some creators may wish to release their NFTs as individual pieces (so-called "1-of-1s"), most will want to create a collection. This is a generic term for a set of NFTs that are intentionally grouped together. For example, an artist could release several paintings of fruit as a collection called "Fruits of the World".

Series​

"Series" describes a set of distinct NFTs that belong together in a collection. Chia NFTs use two parameters in their off-chain metadata related to series:

  • series_number is the sequence number of this NFT in the collection. Following the Fruits of the World example, if the collection consists of ten images of distinct types of fruit, these could be labeled "Fruits of the World #1", "Fruits of the World #2", etc. Typically, NFT collections will list the series number in each NFT's title. However, this is not mandatory. It is also possible to include the series number in the off-chain metadata.
  • series_total is the total number of NFTs in the series. Creators have the option to either specify the series_total upon the collection's initial minting, or to leave this parameter unspecified. In the latter case, potential buyers won't know the total number that will be minted, which could have a negative impact on the price of individual NFTs.

Edition​

"Edition" means multiple NFTs with identical data and metadata. In the NFT1 standard, the NFT's edition is part of the on-chain metadata. This means that it is built into the NFT itself. There are two parameters related to edition:

  • edition_number is the sequence number of this NFT's edition. For example, if the collection contains ten identical images of an apple, the NFTs could be labeled Apple #1 of 10, Apple #2 of 10, etc. The edition_number would then be 1, 2, etc. If each NFT in a collection is distinct, then the edition_number for each NFT is 1. In this case, most NFT creators will choose not to specify this redundant edition_number.
  • edition_total is the total number of identical NFTs that are part of this edition. If edition_number is specified for an NFT, then edition_total is also recommended to be specified. In the above example, each NFT that contains an identical apple image would have an edition_total of 10.

CLVM Cost​

信息

As detailed in our CLVM reference, the CLVM cost for an XCH transaction with two inputs and two outputs is around 17 million.

The cost for minting and modifying NFTs is significantly higher. The following chart shows the approximate CLVM cost (rounded up to the nearest million), as well as the recommended minimum fee (at 5 mojos per cost), and the approximate cost in USD.

Note that the minimum fees listed here will only apply when the mempool is full.

If the mempool is not full, then a 1-mojo fee will be sufficient for any of these spends to be included in the next transaction block. To view the current status of the mempool, see the Mempool Cost table on our dashboard site. (If the green line representing the current mempool cost is close to the red line representing the maximum cost, then the mempool is full, and the following table should be used.)

OperationCost (approx)Min fee (mojos)Cost in USD at $30/XCH
Minting NFT without DID53 million265 million$0.00795
Minting NFT with DID123 million615 million$0.01845
Adding a URI to NFT without DID41 million205 million$0.00615
Transfer NFT with DID67 million335 million$0.01005
Assign DID to NFT107 million535 million$0.01605
Adding URI to NFT with DID71 million355 million$0.01065
Note about Python RuntimeError on Windows

If you are running on Windows, you might occasionally see a Python Runtime Error. This is a known issue in Python and can be safely ignored. For example:

chia stop -d all

Exception ignored in: function _ProactorBasePipeTransport.__del__ at 0x000001A719716160
Traceback (most recent call last):
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\asyncio\proactor_events.py", line 116, in __del__
    self.close()
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\asyncio\proactor_events.py", line 108, in close
    self._loop.call_soon(self._call_connection_lost, None)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\asyncio\base_events.py", line 746, in call_soon
    self._check_closed()
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\asyncio\base_events.py", line 510, in _check_closed
    raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed
daemon: {'ack': True, 'command': 'exit', 'data': {'success': True}, 'destination': 'client', 'origin': 'daemon', 'request_id': '0de5449121b6873ce18661b2adc4213d7dc795c2943ff7f4be9502058e8eaba0'}

Install Testnet​

This section will show you how to install the latest version of Chia, configure your installation to run on the testnet, sync your node, and obtain some TXCH. If you have already done all of these things, you can skip to the next section, Obtain images with corresponding hashes.

提示

Your firewall might give warnings when installing Chia. This is normal. Allow the installations to continue.

You can either run on a full node or use the light wallet. You also have the option of installing from source or using a binary installer.

Binary installer​

If you choose to run a binary installer, download the latest version of Chia from the Chia download page.

After the installer has downloaded, execute it and Chia will install automatically.

信息

If the chia command isn't already in your system's path, you can create an alias:

Be sure to replace <username> and <version> with the actual folder names.

` with the actual folder names.

Set-Alias -Name chia "C:\Users\<username>\AppData\Local\chia-blockchain\app-<version>\resources\app.asar.unpacked\daemon\chia.exe"

Installing from source​

To install Chia from source, follow our installation guide, which includes instructions for installing on all supported operating systems.

Switching to testnet​

By default, Chia will run on mainnet. By default, Chia will run on mainnet. To switch to the testnet (recommended) for this guide, see our testnet instructions.

Configuration​

We recommend that you use INFO level logging instead of the default WARNING level. To do this, run:

chia configure --set-log-level INFO

We recommend that you use a key pair for testnet that is separate from your mainnet keys. If you don't have a separate set of testnet keys, generate them:

chia keys generate

This will give an output such as the following:

Generating private key
Added private key with public key fingerprint 3049838316
(...)
提示

It is good security practice to use this set of keys for testnet development only. In case of key compromise, your TXCH and NFTs will be sandboxed from your XCH.

If you generated new testnet keys in the last step, we recommend that you write down your seed phrase for later recovery. Run the following:

chia keys show --show-mnemonic-seed

You'll be shown your public and private keys. The last line of the output will be a list of 24 secret words. This is your seed phrase. Carefully copy the words on paper and store them in a secure location. Order is important.

Showing all public and private keys

Fingerprint: 3049838316
(...)
    Mnemonic seed (24 secret words):
youth stomach social aware clay pottery benefit asthma mail cry rubber panda wife around provide atom cute sand staff exotic pink east gloom minute
important

Your seed phrase is all that is required to recover your wallet. If you lose your seed phrase, recovery will not be possible. If a bad actor gains access to your seed phrase, they'll be able to steal your Chia assets, including XCH, CATs and NFTs.

信息

If you ever need to display your address, run chia keys show. This command will only output your public keys and address; your private keys and seed phrase will not be shown.

Note: At this point we'll start the Chia light wallet, but not the full node. As noted above, the full node is not required for minting NFTs, but it will generally be faster than the light wallet.

Start your wallet by running:

chia start wallet

Wait for your wallet to sync. You can view the status of your wallet with the following command:

chia wallet show

Be sure to select the correct key/fingerprint, which you obtained from the chia keys show command:

Wallet keys:
1)   285637561
2) * 3049838316 (Not Synced)
Choose a wallet key [1-2] ('q' to quit, or Enter to use 3049838316):
Wallet height: 938814
Sync status: Syncing...

Syncing should only require a few minutes, unless your wallet has a large number of previous transactions. Eventually, the chia wallet show command will show that your wallet has been synced. For example:

Wallet height: 938990
Sync status: Synced
Balances, fingerprint: 3049838316

Chia Wallet:
   -Total Balance:         14.5 txch (14500000000000 mojo)
   -Pending Total Balance: 14.5 txch (14500000000000 mojo)
   -Spendable:             14.5 txch (14500000000000 mojo)
   -Type:                  STANDARD_WALLET
   -Wallet ID:             1

In order to continue, you'll need to have some TXCH in your wallet. If your total balance is 0, you can obtain 1 TXCH from our faucet. Copy the value of "First wallet address:" from the output of the chia keys show command. It will be a long string beginning with "txch".

Open our testnet faucet page. Paste your address and click "Submit". Paste your address and click "Submit".

You'll receive this message: Accepted. Your request is in the queue and will be processed in the order it was received. At some point you'll receive 1 TXCH. Depending on how busy the faucet and the testnet are, this could take several minutes. However, you don't need to wait for your coins to arrive before continuing.

(Optional) Start the full node:

chia start node
chia_full_node: started

Check the sync status:

chia show -s

Eventually, it will say Full Node Synced:

Network: testnet10    Port: 58444   RPC Port: 8555
Node ID: 82a73b06b3a5f9493a3ac4e3d903026b39c85b748158ba41c623d531947f2a2a
Genesis Challenge: ae83525ba8d1dd3f09b277de18ca3e43fc0af20d20c4b3e92ef2a48bd291ccb2
Current Blockchain Status: Full Node Synced

Once you have a synced wallet and some TXCH, you may proceed to the next section. If your requested TXCH has not yet arrived, post your address on the #dev channel on Discord. Someone might be able to send some to you.

Note about Chia wallets

In Chia, each public/private key pair can hold multiple wallets of various types.

A "fingerprint" is a 4-byte hash of a public key. The computer running the examples we'll use in the next sections had two public/private key pairs, and thus two fingerprints, labeled 1) and 2).

Note that simultaneous syncing of multiple fingerprints is not currently possible. Whether you're using the CLI or the GUI (in general, not just for NFTs) you have to select one of the fingerprints to sync, while the other will be temporarily ignored and not synced.

Within each of the fingerprints, you can store multiple wallets of various types. The default wallet is a Chia Wallet, aka a STANDARD_WALLET. This label is part of an enum with a value of 0. The other wallet types are as follows:

STANDARD_WALLET = 0
RATE_LIMITED = 1
ATOMIC_SWAP = 2
AUTHORIZED_PAYEE = 3
MULTI_SIG = 4
CUSTODY = 5
CAT = 6
RECOVERABLE = 7
DECENTRALIZED_ID = 8
POOLING_WALLET = 9
NFT = 10

A few notes about this enum:

  • The only types that are supported as of June 2022 are STANDARD_WALLET, DECENTRALIZED_ID, CAT, and NFT
  • Each fingerprint/Wallet Key can support each of the following:
    • One STANDARD_WALLET
    • An unbounded number of CATs
    • An unbounded number of DECENTRALIZED_IDs
    • One NFT wallet per DECENTRALIZED_ID (where each NFT wallet is associated with exactly one DECENTRALIZED_ID)
    • One additional NFT wallet that is not associated a DECENTRALIZED_ID
  • If an existing NFT wallet is already associated with a DECENTRALIZED_ID, then an attempt to create a new NFT wallet associated with the same DECENTRALIZED_ID will pass, but it will not actually create the NFT wallet because it already exists
  • If an existing NFT wallet is not associated with a DECENTRALIZED_ID, then an attempt to create a new NFT wallet that is not associated with a DECENTRALIZED_ID will pass, but it will not actually create the NFT wallet because it already exists
  • In addition to a type, each wallet also has a Wallet ID. This is simply an integer that increments for each new wallet.

For example, the following setup would be possible to run on a single computer:

  • Wallet Key 1 (not synced)
    • Chia Wallet (Type = STANDARD_WALLET, Wallet ID = 1)
    • Marmot (Type = CAT, Wallet ID = 2)
  • Wallet Key 2 (synced)
    • Chia Wallet (Type = STANDARD_WALLET, Wallet ID = 1)
    • NFT Wallet (Type = NFT, Wallet ID = 2)
    • Marmot (Type = CAT, Wallet ID = 3)
    • Spacebucks (Type = CAT, Wallet ID = 4)
  • Wallet Key 3 (synced)
    • Chia Wallet (Type = STANDARD_WALLET, Wallet ID = 1)
    • NFT Wallet (Type = NFT, Wallet ID = 2, not associated with a DID)
    • DID Wallet (Type = DECENTRALIZED_ID, Wallet ID = 3)
    • DID Wallet (Type = DECENTRALIZED_ID, Wallet ID = 4)
    • NFT Wallet (Type = NFT, Wallet ID = 5, associated with DID from Wallet ID 3)

Under Wallet Key 3 of this setup, it would not be possible to create another NFT wallet that is not associated with a DID, or another DID wallet that is associated with the DID from Wallet ID 3. However, it would be possible to create an NFT wallet that is associated with the DID from WALLET ID 4. It would also be possible to create a new DID within Wallet Key 3.

Obtain images with corresponding hashes​

For this guide, we'll obtain two images and hashes to be used for creating NFTs with the following use cases:

  • CLI, with DID
  • RPC, with DID

Here's the general technique to obtain images and hashes:

First, find an image to mint as an NFT. For this example, we'll use an image that is licensed in the public domain: https://images.pexels.com/photos/11053072/pexels-photo-11053072.jpeg

Then, calculate the image's hash. Here are three (of many) options:

  • cURL with sha256sum. If you're on Windows, you'll need to run this command from Git Bash.

    curl -s https://images.pexels.com/photos/11053072/pexels-photo-11053072.jpeg | sha256sum
    14836b86a48e1b2b5e857213af97534704475b4c155d34b2cb83ed4b7cba2bb0 *-

  • cURL with shasum. If you're on Windows, you'll need to run this command from Git Bash.

    curl -s https://images.pexels.com/photos/11053072/pexels-photo-11053072.jpeg | shasum -a 256
    14836b86a48e1b2b5e857213af97534704475b4c155d34b2cb83ed4b7cba2bb0 *-

  • Save the image locally. Visit https://emn178.github.io/online-tools/sha256_checksum.html. Upload the image and click the Hash button.

In all three cases, the hash for this sample image is 14836b86a48e1b2b5e857213af97534704475b4c155d34b2cb83ed4b7cba2bb0.

The following is a list of the sample images and hashes this guide will use, along with the metadata and license information. Additionally, we'll use multiple copies of the Metadata URI with these NFTs.

CLI, with DID​

RPC, with DID​

Where to store images for NFTs​

In theory you can use any hosting site to host your NFT images. However, do make sure that the service doesn't modify the image at all. Doing so will also change the hash and make it more likely to be lost long-term. The best way to verify this is to use each of the above techniques to generate the image hash, and make sure they all match.

Certain decentralized services such as IPFS can be slow. The first time a user attempts to view an NFT in their wallet (before caching), it might take a long time to load.

Chia NFTs use a list to store image URIs, so it is possible to add multiple locations to increase permanence. However, do make sure each image's hash is the same as the data hash.

NFT Metadata Standards​

Since the original release of this guide, a CHia Improvement Proposal (CHIP) that standardizes the JSON metadata schema for Chia NFTs has been finalized.

See CHIP-7 for the correct formatting. Usage of this CHIP is recommended in order to give marketplaces the best opportunity to parse your NFTs' metadata properly.

Note that additional NFT metadata CHIPs are likely to be released in the future. However, there are no plans to deprecate CHIP-7 when this happens.