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Blockchain Validated Asset Metadata

Note: The terms 'asset' and 'token' can be used interchangeably

Blockchain Validated Asset Metadata (BVAM) is a method which allows Counterparty Asset metadata to be stored off-blockchain as JSON data, yet still be verifiable and inalterable by storing the hash of the JSON data in the Counterparty Asset description.

BVAM must define, at a minimum, the 'asset' element within the JSON data. This conforms to the current Counterparty Enhanced Asset Info documentation. Additional elements can also be customized to meet the needs of each wallet provider. Elements should be listed in alphabetical order to ensure repeatability of the JSON data hash.

There are two methods for storing BVAM JSON data which are recognized by the Pockets wallet, server method (via xcp.ninja) and p2p method (via Webtorrent protocol)

Example BVAM json, http://xcp.ninja/hash/TB2rTB5FdLtqYu31wTmKgy54TYeZSqJgr3.json

Referenced Counterparty Asset, https://counterpartychain.io/asset/A11161111624187815485

Server Method

  1. A third party service(s) hosts a JSON file with Enhanced Asset info (this is inline with the current protocol). For Tokenly Pockets, this is currently limited to xcp.ninja only.

  2. When issuing a new asset in Counterparty, the asset description references the hash of the stringify'd enhanced asset JSON data (instead of referencing the URL of the JSON file in the asset description). To save space, the SHA256 hash is encoded, similar to a bitcoin public key but with the version numbered altered to display a "T" as the first character instead of a "1".

    Example BVAM hash: TB2rTB5FdLtqYu31wTmKgy54TYeZSqJgr3

    var jsondata = '{"ownername":"ABC Inc.","ownertwitter":"@abcinc","owneraddress":"1GcFhAQGFZVDAr4jiR2tKwisHcgNUjhGNC","asset":"A11161111624187815485","assetname":"Widget","assetdescription":"Good for one widget.","assetwebsite":"http://abcwidgets.com"}'

var firstSHA = Crypto.SHA256(jsondata)

var hash160 = Crypto.RIPEMD160(Crypto.util.hexToBytes(firstSHA))
var version = 0x41 // "T"
var hashAndBytes = Crypto.util.hexToBytes(hash160)
hashAndBytes.unshift(version)

var doubleSHA = Crypto.SHA256(Crypto.util.hexToBytes(Crypto.SHA256(hashAndBytes)))
var addressChecksum = doubleSHA.substr(0,8)

var unencodedAddress = "41" + hash160 + addressChecksum

var address = Bitcoin.Base58.encode(Crypto.util.hexToBytes(unencodedAddress))

    http://jsfiddle.net/k0jk49km/

  3. The hash is prefixed in the asset description with "TOKNID-" for wallet software to identify that an asset has associated BVAM. This represents a 41-byte asset description.

    Example Asset Description: TOKNID-TB2rTB5FdLtqYu31wTmKgy54TYeZSqJgr3

  4. Wallet software can query any third party service and trust that the data is valid without the need to trust the source. This is accomplished by independently verifying the data hash within the wallet using the method in Step 2.

p2p Method

BVAM via Webtorrent can be enabled in the Wallet Settings tab of Tokenly Pockets. Once downloaded, Pockets caches BVAM locally for future reference.

  1. Token issuers seed BVAM JSON files with Enhanced Asset info via Webtorrent. BVAM creation and seeding is currently available at xcp.ninja. Token issuance, BVAM creation and seeding (via Webtorrent Control Panel) is available in the current Repository v0.2.1

  2. When issuing a new asset in Counterparty, the asset description references the Webtorrent infohash of the enhanced asset JSON file named BVAMWT.json which contains BVAM unique to that asset. To save space, the Webtorrent infohash is Base58 encoded.

  3. The hash is prefixed in the asset description with "BVAMWT-" for wallet software to identify that an asset has an associated BVAM Webtorrent.

    Example Asset Description: BVAMWT-4SL14zw8RoTco96bTwtdKwnXGXcZ

  4. Wallet software can Base58 decode the infohash and query Webtorrent peers to download BVAM.