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SBT-20 TOKEN STANDARD.md

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SBT-20 TOKEN STANDARD

INTRODUCTION

What is a Token? Tokens can represent virtually anything in Bitcoin: reputation points in an online platform skills of a character in a game lottery tickets financial assets like a share in a company a fiat currency like USD an ounce of gold and more... Such a powerful feature of Bitcoin must be handled by a robust standard, right? That's exactly where the SBT-20 plays its role! This standard allows developers to build smart token applications that are interoperable with other products and services in the Bitcoin Network

What is SBT-20? The SBT-20 introduces a standard for Fungible Tokens, in other words, they have a property that makes each Token be exactly the same (in type and value) as another Token. Meaning 1 Token is and will always be equal to all the other Tokens.

PREREQUISITES

Accounts: Smart Contracts: Token standards:

BODY The SBT-20 (Bitcoin Smart Tokens 20), builds on the ERC-20 standard proposed by Fabian Vogelsteller in November 2015, which is a Token Standard that implements an API for tokens within Smart Contracts. The SBT-20 standard expands this implementation adding smart functionality to Bitcoin tokens for all Bitcoin EVM scaling networks to adopt. Example functionalities SBT-20 provides:

transfer tokens from one account to another get the current token balance of an account get the total supply of the token available on the network approve whether an amount of token from an account can be spent by a third-party account If a Smart Contract implements the following methods and events it can be called an SBT-20 Token Contract and, once deployed, it will be responsible to keep track of the created tokens on Bitcoin.

METHODS function name() public view returns (string) function symbol() public view returns (string) function decimals() public view returns (uint8) function totalSupply() public view returns (uint256) function balanceOf(address _owner) public view returns (uint256 balance) function transfer(address _to, uint256 _value) public returns (bool success) function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) function approve(address _spender, uint256 _value) public returns (bool success) function allowance(address _owner, address _spender) public view returns (uint256 remaining)

EVENTS event Transfer(address indexed _from, address indexed _to, uint256 _value) event Approval(address indexed _owner, address indexed _spender, uint256 _value)

Examples Let's see how a Standard is so important to make things simple for us to inspect any SBT-20 Token Contract on Bitcoin. We just need the Contract Application Binary Interface (ABI) to create an interface to any SBT-20 Token. As you can see below we will use a simplified ABI, to make it a low friction example.

Web3.py Example

First, make sure you have installed Web3.py(opens in a new tab) Python library: pip install web3

Then: from web3 import Web3

w3 = Web3(Web3.HTTPProvider("https://cloudflare-eth.com"))

dai_token_addr = "0x6B175474E89094C44Da98b954EedeAC495271d0F" # DAI weth_token_addr = "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2" # Wrapped ether (WETH)

acc_address = "0xA478c2975Ab1Ea89e8196811F51A7B7Ade33eB11" # Uniswap V2: DAI 2

This is a simplified Contract Application Binary Interface (ABI) of an ERC-20 Token Contract.

It will expose only the methods: balanceOf(address), decimals(), symbol() and totalSupply()

simplified_abi = [ { 'inputs': [{'internalType': 'address', 'name': 'account', 'type': 'address'}], 'name': 'balanceOf', 'outputs': [{'internalType': 'uint256', 'name': '', 'type': 'uint256'}], 'stateMutability': 'view', 'type': 'function', 'constant': True }, { 'inputs': [], 'name': 'decimals', 'outputs': [{'internalType': 'uint8', 'name': '', 'type': 'uint8'}], 'stateMutability': 'view', 'type': 'function', 'constant': True }, { 'inputs': [], 'name': 'symbol', 'outputs': [{'internalType': 'string', 'name': '', 'type': 'string'}], 'stateMutability': 'view', 'type': 'function', 'constant': True }, { 'inputs': [], 'name': 'totalSupply', 'outputs': [{'internalType': 'uint256', 'name': '', 'type': 'uint256'}], 'stateMutability': 'view', 'type': 'function', 'constant': True } ]

dai_contract = w3.eth.contract(address=w3.to_checksum_address(dai_token_addr), abi=simplified_abi) symbol = dai_contract.functions.symbol().call() decimals = dai_contract.functions.decimals().call() totalSupply = dai_contract.functions.totalSupply().call() / 10decimals addr_balance = dai_contract.functions.balanceOf(acc_address).call() / 10decimals

DAI

print("===== %s =====" % symbol) print("Total Supply:", totalSupply) print("Addr Balance:", addr_balance)

weth_contract = w3.eth.contract(address=w3.to_checksum_address(weth_token_addr), abi=simplified_abi) symbol = weth_contract.functions.symbol().call() decimals = weth_contract.functions.decimals().call() totalSupply = weth_contract.functions.totalSupply().call() / 10decimals addr_balance = weth_contract.functions.balanceOf(acc_address).call() / 10decimals

WETH

print("===== %s =====" % symbol) print("Total Supply:", totalSupply) print("Addr Balance:", addr_balance)

//Read more about EVM examples here: https://docs.openzeppelin.com/contracts/3.x/tokens#ERC20