BlackFort Exchange Network

Concept

Default Ethereum Clique Blockchain based on PoA. Go-Ethereum is forked and used without any additional changes

Type of hosted nodes

Type	Amount	Connection	Description
Validator	As amount of validators (at least 5)	Private, to Bootnodes	Used to seal new blocks in blockchain, fetching the data coming to Bootnodes. They use unlocked accounts, so they should keep safe from any other connection type, except ingress/egress data exchange with Bootnodes
Bootnodes	At least 3	Public, to Peer and other Bootnodes. Private to Validator Validator and other bootnodes	Used as a core of data exchanging between Peer and Validator, because we can't grant access to Validator, because of unlocked account
Peer	No limit	Public, to any of Bootnodes	Just regular Peer node for storing a copy of blockchain on your machine
Explorer	1 - 2	Public, to any of Bootnodes	Same as Peer, but used for providing data to blockchain explorer

Smart Contracts

Setup

System, NodeHub, ValidatorHub, DelegatorHub, VoteHub, CandidateHub, SlashingHub, PollHub are deployed on genesis block, though for testing purposes you can deploy them manually using TEST_setSystemContract method to replace SYSTEM_CONTRACT_ADDRESS in SystemAccess contract. AccessControlHub is deployed manually. We have to save names of contracts in System in snake case e.g. NODE_HUB which is used for finding other system contracts and with approving of spending of certain amount of BXN. Unfortunately we have problem with approving AccessControlHub which must be done first, so if you have solution without hardcoding in contracts, please let me know. See Allocation to know allocation of BXN and approved amounts

Allocation

Name	Address	Allocation on start (BXN)	Approved to spend (BXN)
AccessControlHub	Manually deployed	0	0
System	0x0000000000000000000000000000000000001000	47,777,777,777	Not related
NodeHub	0x0000000000000000000000000000000000001001	0	29,500,000,000
ValidatorHub	0x0000000000000000000000000000000000001002	0	2^256^ (unlimited)
DelegatorHub	0x0000000000000000000000000000000000001003	0	2^256^ (unlimited)
VoteHub	0x0000000000000000000000000000000000001004	0	0
CandidateHub	0x0000000000000000000000000000000000001005	0	0
SlashingHub	0x0000000000000000000000000000000000001006	0	0
PollHub	0x0000000000000000000000000000000000001007	0	0
SaleHub	Not a smart contract (operated by one of our's account)	10000 (reserve for making transactions)	15,000,000,000 (approx number)

AccessControlHub

Contract is used for managing accessing for protected methods across all core smart contracts. Also it manages pausing/unpausing transfers for a bunch of core contracts + Bx assets (wrapped BTC, ETH and so on), which will be managed by us. Most of functionality is inherited from AccessControl of OpenZeppelin

Method	Arguments	Returns	Description
transfersAvailable	address	bool	returns whether the address (contract) has transfers enabled
hasStringRole	string memory, address	—	override on AccessControl's hasRole method accepting human-readable string instead of bytes in the code
enableTransfers	address	—	enables transfers for given address of core smart contract
disableTransfers	address	—	same as above, but disables

System

Core contract that locks whole blockchain supply. Used to store supply and grant it to users/contracts. Withdraw of token is managed by limited set of contracts that can do and the total amount they can withdraw from the contract

Works as coinbase, block sealers must send rewards there for their further distribution

Method	Arguments	Returns	Description
approve	address, string memory, uint256	—	Method to approve spending of certain amount of tokens from the System. Also saves name of the contract that can be used for finding it without using addresses in the code, e.g. NODE_HUB will stand for 0x0000000000000000000000000000000000001001 (check getAddressOf)
approvedAmountOf	address	uint256	Returns approved amount for certain address
spentAmountOf	address	uint256	Returns spent amount for certain address
getAddressOf	string memory	address	Returns address by contract name
receive	—	—	Default method for receiving BXN. If it was sent by block sealer (validator), it will be distributed as a reward. Otherwise just stays in the System
transferTo	address, uint256	bool	Used to send certain amount of token to certain address. Allowed to use only by approved contracts/addresses

NodeHub

ERC721 compatible token used to describe the BXN NODE Token, which unlocks BXN from the System for approx. next 10 years after mint. NODE doesn't have any common with hosted nodes. By minting NODE you're going to unlock BXN from the System, reward is collected each block

Method	Arguments	Returns	Description
receive	—	—	Default receive method
balanceOf	address	uint256	As in ERC721
ownerOf	uint256	address	As in ERC721
tokenOfOwnerByIndex	address, uint256	uint256	Extension of ERC721
isLocked	uint256	bool	Returns if token is locked
mintedWith	uint256	uint256	Amount of BXN minted with certain NODE token
mintedBy	address	uint256	mintedWith applied on all NODE tokens that are held by given address
burnedBy	address	uint256	Amount of reward burned by certain address
availableBalanceOf	address	uint256	Amount of reward which is available to burn
rewardShareFor	uint256	uint256	reward share of given NODE, equals to block reward of NODE
rewardShareOf	address	uint256	rewardShareFor applied on all NODE tokens that are held by given address
delegatedTo	uint256	address	Returns address of the validator to which that NODE is delegated
mint	address	—	Accepts payment and mints new NODEs to the address, depending on invested amount. Also checks for not exceeding of deposit limit and gives you some amount of VOTE token. Always refunds not used for purchase BXN
lock	uint256	—	Locks the NODE. Locked NODE can't earn anything. Can be run only by SaleHub
unlock	uint256	—	Unlocks the NODE. Can be run only by SaleHub
delegate	address	uint256	Delegates NODE to given validator address. Undelegates if delegatedTo is address(0)
_burnFrom	address, uint256	—	Burns given amount from availableBalanceOf giving back BXN from System
_beforeTokenTransfer	address, address, uint256	—	Upgraded method to handle some processes on NODE transfer to new owner e.g. undelegating, burning reward
_baseURI	—	string memory	returns URI prefix to our pictures

ValidatorHub

ERC20/BXP20 compatible token used to describe the block sealer e.g. validator, which sends transaction fee to the System in order to distribute it

Method	Arguments	Returns	Description
receive	—	—	Default receive method used to top up validator's self bonded amount of BXN
isValidator	address	bool	Is the given address a validator
commissionOf	address	uint256	returns validator's commission (4951 stands for 49.51%)
setCommission	uint256	—	Method for setting commission of validator. Value must be in range (0, 5000)
selfBondedAmountOf	address	uint256	Returns self bonded amount of validator. 0 if that user is not validator
mint	address, uint256	—	Method used by System to mint validator's reward
join	address	—	Method accepts new validator, is run by CandidateHub contract
kick	address	bool	Kicking of validator, performed only with VALIDATOR_MANAGER_ROLE. Self bonded amount is returned back to validator's account

DelegatorHub

ERC20/BXP20 compatible token used to describe the block sealer e.g. validator, which sends transaction fee to the System in order to distribute it

Method	Arguments	Returns	Description
increaseDelegatedAmountFor	address, uint256	—	Processes the calculations of changing of shares (increases)
decreaseDelegatedAmountFor	address, uint256	—	Just the same as above, but decrease
delegatedAmountOf	address	uint256	returns amount of tokens delegated to validator (sum of all costs of NODEs delegated)
mintedWith	uint256	uint256	returns total amount of reward earned by certain NODE
mintedBy	address	uint256	returns total amount of reward earned by NODEs owned by certain address
mint	address, uint256	—	Method used by System to mint delegator's reward of certain validator
burnExtraFor	uint256	—	burns all reward earned by certain token

VoteHub

ERC20/BXP20 compatible token used as voting power on blockchain. At start used in polls by PollHub. Can be used by multiple projects in future

Method	Arguments	Returns	Description
mint	address, uint256	—	Mints the VOTE token for certain address if msg.sender is allowed to do that
burn	address, uint256	—	Same as above, but burns the VOTE and gives instead BXN token. Available only for certain msg.sender's
allowance	address, uint256	—	same as allowance in ERC20/BXP20, but for PollHub it's always equals to balanceOf

CandidateHub

Small contract that used to accept new validators of hosted nodes (they would require to install software too)

Method	Arguments	Returns	Description
receive	—	—	Default receive account used to add new candidate. Account should pass certain limit to become a candidate
accept	address	—	makes candidate a validator and moves self bonded amount to ValidatorHub
reject	address	—	rejects candidate and returns back deposited amount
selfBondedAmountOf	address	uint256	Returns self bonded amount of candidate. 0 if that user is not validator
setRequiredAmount	uint256	—	sets required amount to become candidate

SlashingHub

Contract is used for slashing validator

Method	Arguments	Returns	Description
isSlashed	address	bool	returns true if validator is slashed
slashedByBlock	address	—	returns block number until the validator is slashed, 0 returned is validator is not slashed
timesSlashed	address	—	count of times of certain validator was slashed
slash	address, uint8	—	slashes the validator untils the certain block number, reducing his further rewards for some period of time

PollHub

Contract is used for managing on-chain polls. Public to everyone. Poll represents ERC721 token

Method	Arguments	Returns	Description
setRequiredAmountOfVote	uint256	—	sets required amount of VOTE token that creator of Poll must have
setRequiredAmountOfBXN	uint256	—	sets required amount of BXN token that creator of Poll must have
setPollPrice	uint256	—	sets price of initiation of the Poll
setPollCreatorFee	uint256	—	sets the fee that creator of the Poll receives on each amount of VOTE spent with vote method
mint	string memory	—	mints Poll with the given title
burn	uint256	—	burns Poll token if poll was not opened e.g. voting started of finished
titleOf	uint256	string memory	returns title of existing Poll
updateTitle	uint256, string memory	—	updates title of certain Poll
optionOfPollByIndex	uint256, uint256	string memory	returns text of option by optionId of given Poll
optionsCountOf	uint256	uint256	returns count of options of given Poll
addOption	uint256, string memory	—	adds new option for not opened Poll
removeOption	uint256, uint256	—	removes option of the poll, by given optionId
updateOption	uint256, uint256, string memory	—	updates the option of the Poll by given string and optionId
start	uint256, uint8	—	opens not yet opened Poll with preset deadline block number
deadlineBlockOf	uint256	uint8	returns deadline block number (block number when the Poll closes)
updateDeadlineBlock	uint256, uint8	—	updates deadline block number for given Poll
vote	uint256, uint256, uint256	—	vote for certain option of certain Poll with certain amount of VOTE token
votesByOptionOf	uint256, uint256	uint256	returns amount of VOTE spent for given optionId of given Poll
totalVotesOf	uint256	uint256	returns total amount of VOTE was spent in the Poll

Inherited Smart Contracts

SystemAccess

Contract defines certain internal methods to make available interaction between different core contracts without declaring address references

Method	Arguments	Returns	Description
_getSystemContractInstance	—	ISystem	returns ISystem interface of System contract
_getAddressOf	string memory	address	override of getAddressOf method of System contract
hasRole	string memory, address	bool	override of hasStringRole method of AccessControlHub contract

BXP20SystemRewardToken

Contract (re)defines methods of BXP20 to be compatible with ValidatorHub and DelegatorHub

Method	Arguments	Returns	Description
TBA	—	TBA	TBA

BXP20

BXP20 realization is a slightly extended version of OpenZeppelin's ERC20. Additional methods are mint and burn which are allowed to run only by asset manager address. Other details are to be announced and described

How it would work

Regular user

Regular user can buy BXN token through our web interface or exchange it on DEX (in future). We send out BXN from System. Access to it will be available only to one address that will be responsible for sales (aka SaleHub)

User also can buy NODEs. User can do it by himself sending BXN to NodeHub. Amount depends on NODEs the user wants to obtain. Also ther will be possibility to buy BXN tokens to spend them on NODEs (means that SaleHub requests to send BXN from System directly to NodeHub's mint method mentioning the recepient's address

NODE Owner

NODE owner can get the block reward using burn method, System will send him BXN tokens. Also NODE owner can delegate his NODEs across different validators using delegate method of NodeHub

If NODE is delegated to a validator, NODE owner can obtain share of reward that validator shall always send to System for futher distribution. In order to get BXN, user must burn the DelegatorHub token, which acts as BXP20 token and burns at 1:1 rate

Validator

Validators seal the blocks and are responsible for sharing all their rewards with System contract. Sharing of reward is automated and managed by etherbase.js script that we provide. Any misbehaviour including changing of that script will lead to punishment (slashing). Slashing reduces reward share of validator increasing the share of delegators

Validators must have self bonded amount of BXN to seal the blocks. New validators always share their self bonded amount with CandidateHub, after we accept new validator with clique.propose on-chain vote, we additionaly accept him in smart contracts and give access to ValidatorHub contract which allows them to set their own commission for their work and also receiving their validator's reward with burn of ValidatorHub token which acts as BXP20 token and burns at 1:1 rate