KAP-721

The following standard outlines a smart contract interface and logic for non-fungible tokens on KUB that supports an adminTransfer function designed to create transactions on behalf of NFT holders if they have been a victim of a fraudulent transaction. It is proposed by deriving the ERC-721 standard of Ethereum with additional functions related to adminTransfer.

Token Interface

IAdminProjectRouter

isSuperAdmin

Check whether _addr is the Super Admin role in _project.

function isSuperAdmin(address _addr, string calldata _project) external view returns (bool)

isAdmin

Check whether _addr is the Admin role in _project.

function isAdmin(address _addr, string calldata _project) external view returns (bool)

IKYCBitkubChain

kycsLevel

Returns the KYC Level of _addr.

function kycsLevel(address _addr) external view returns (uint256)

IKAP165

supportsInterface

Check whether the contract implements interfaceID and the interfaceID is not 0xffffffff.

function supportsInterface(bytes4 interfaceId) external view returns (bool)

NOTE: Query if the contract implements an interface

IKAP721

balanceOf

Returns the number of NFTs owned by the address owner, possibly zero.

function balanceOf(address owner) external view returns (uint256 balance)

NOTE: NFTs assigned to the zero address are considered invalid, and this function throw for queries about the zero address.

ownerOf

Returns the address owner of the owner of the NFT tokenID.

function ownerOf(uint256 tokenId) external view returns (address owner);

NOTE: NFTs assigned to the zero address are considered invalid, and this function throw for queries about the zero address.

safeTransferFrom

Transfers the ownership of NFT tokenID from address from to address to.

• throw unless msg.sender is the current owner, an authorized operator, or the approved address for this NFT tokenID.

• throw if from is not the current owner.

• throw if to is the zero address.

• throw if tokenID is not a valid NFT.

When the transfer is complete, this function checks if to is a smart contract (code size > 0). If so, it calls onKAP721Received on to and throw if the return value is not bytes4(keccak256("onKAP721Received(address,address,uint256,bytes)")).

function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external

transferFrom

Transfers the ownership of NFT tokenID from address from to address to.

• throw unless ‘msg.sender‘ is the current owner, an authorized operator, or the approved address for this NFT tokenID.

• throw if from is not the current owner.

• throw if to is the zero address.

• throw if tokenID is not a valid NFT.

function transferFrom(address from, address to, uint256 tokenId) external

NOTE: The caller is responsible to confirm that to address is capable of receiving NFTs, or else they may be permanently lost.

adminTransfer

Transfers NFT tokenID from address from to address to, and MUST fire the Transfer event.

function adminTransfer(address from, address to, uint256 tokenId) external

NOTE: This function can only be called by the Committee address required in the constructor. This function is designed to create transactions automatically on behalf of NFT holders if they have been a victim of a fraudulent transaction. This method works similarly to the transferFrom method.

internalTransfer

Transfers NFT tokenID to address to internally from address from, and MUST fire the Transfer event. The function SHOULD throw if the message caller’s account balance does not have the specify NFT tokenID. NFTs can be transferred between internal addresses that have completed KYC for both the address from and the address to using the internalTransfer function.

function internalTransfer(address from, address to, uint256 tokenId) external returns (bool)

NOTE: This function can only be called by the Super Admin and the Transfer Router.

externalTransfer

Transfers NFT tokenID to address to externally from address from, and MUST fire the Transfer event. The function SHOULD throw if the message caller’s account balance does not have the specified NFT tokenID. The function externalTransfer allows NFTs to be transferred between addresses that have only passed the sender’s KYC verification process.

function externalTransfer(address from, address to, uint256 tokenId) external returns (bool)

NOTE: This function can only be called by the Super Admin and the Transfer Router.

approve

Change or reaffirm the approved address for an NFT tokenID to the address to. The zero address indicates there is no approved address.

throw unless msg.sender is the current NFT owner, or an authorized operator of the current owner.

function approve(address to, uint256 tokenId) external

getApproved

Returns the approved address operator for this NFT tokenID, or the zero address if there is none.

throw if tokenID is not a valid NFT.

function getApproved(uint256 tokenId) external view returns (address operator)

setApprovalForAll

Enable or disable approval for a third party operator to manage all of msg.sender's assets.

approve true if the operator is approved, false to revoke approval.

Emits the ApprovalForAll event. The contract MUST allow multiple operators per owner.

function setApprovalForAll(address operator, bool approved) external

isApprovedForAll

Check whether operator is an approved operator for owner.

function isApprovedForAll(address owner, address operator) external view returns (bool)

NOTE: Query if an address operator is an authorized operator for another address owner.

safeTransferFrom

Transfers the ownership of NFT tokenID from address from to address to. This works identically to the other function with an extra data parameter, except this function sets data to “”.

function safeTransferFrom(address from, address to, uint256 tokenId) external

Events

Transfer

This event emits when ownership of any NFT tokenID changes by any mechanism, when NFTs are created (from == 0), and when NFTs are destroyed (to == 0).

event Transfer(address indexed from, address indexed to, uint256 indexed tokenId)

EXCEPTION: During contract creation, any number of NFTs may be created and assigned without emitting Transfer. At the time of any transfer, the approved address for that NFT (if any) is reset to none.

Approval

This event emits when the approved address for an NFT tokenID is changed or reaffirmed. The zero address indicates there is no approved address. When a transfer event emits, this also indicates that the approved address for that NFT (if any) is reset to none.

event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId)

ApprovalForAll

This event emits when operator is enabled or disabled for owner. The operator can manage all NFTs of the owner.

event ApprovalForAll(address indexed owner, address indexed operator, bool approved)

IKAP721V2

tokenOfOwnerByPage

Returns the list of token identifier for the NFT from page to limit assigned to owner, (sort order not specified).

• throw if limit is greater than or equals to balanceOf(owner)

• throw if page is less than 0

• throw if limit is less than 0

• throw if owner is the zero address, representing invalid NFTs.

function tokenOfOwnerByPage(address owner, uint256 page, uint256 limit) external view returns (uint256[] memory)

tokenOfOwnerAll

Returns the array of all token identifiers for the NFT assigned to owner, (sort order not specified).

function tokenOfOwnerAll(address owner) external view returns (uint256[] memory)

adminApprove

Change or reaffirm the approved address for an NFT tokenID to the address to. The zero address indicates there is no approved address. This method works similarly to the approve method.

throw unless msg.sender is the current NFT owner, or an authorized operator of the current owner.

function adminApprove(address to, uint256 tokenId) external

NOTE: This function can only be called by the Admin and Super Admin. This function is designed to create transactions automatically on behalf of token holders if they have been victims of a fraudulent transaction.

adminSetApprovalForAll

Enable or disable approval for a third party operator to manage all of msg.sender assets. approve true if the operator is approved, false to revoke approval. This method works similarly to the setApprovalForAll method.

Emits the ApprovalForAll event. The contract MUST allow multiple operators per owner.

function adminSetApprovalForAll(address owner, address operator, bool approved) external

NOTE: This function can only be called by the Admin and Super Admin. This function is designed to create transactions automatically on behalf of token holders if they have been victims of a fraudulent transaction.

IKAP721Metadata

name

A descriptive name for a collection of NFTs in this contract.

function name() external view returns (string memory)

symbol

An abbreviated name for NFTs in this contract

function symbol() external view returns (string memory)

tokenURI

A distinct Uniform Resource Identifier (URI) for a given asset.

throw if tokenID is not a valid NFT. URIs are defined in RFC 3986. The URI may point to a JSON file that conforms to the “KAP721 Metadata JSON Schema”.

function tokenURI(uint256 tokenId) external view returns (string memory)

IKAP721Enumerable

totalSupply

Returns a count of valid NFTs tracked by this contract, where each one of them has an assigned and queryable owner not equal to the zero address.

function totalSupply() external view returns (uint256)

tokenOfOwnerByIndex

Returns the token identifier for the index NFT assigned to owner, (sort order not specified).

throw if index is greater than or equal to balanceOf(owner) or if owner is the zero address, representing invalid NFTs.

function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId)

tokenByIndex

Returns the token identifier for the index NFT, (sort order not specified).

throw if index is greater than or equal to totalSupply()

function tokenByIndex(uint256 index) external view returns (uint256)

IKAP721Receiver

onKAP721Received

The KAP721 smart contract calls this function on the recipient after a Transfer. This function MAY throw to revert and reject the transfer. Return of other than the magic value bytes4(keccak256("onKAP721Received(address,address,uint256,bytes)")) MUST result in the transaction being reverted.

function onKAP721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4)

NOTE: The contract address should always be the message sender.