Demo: ETH-BNC bridge
These instructions describe how to run the bridge between an Ethereum-based chain and the Binance Chain testnet.
This demo supports two ways of dealing with the Ethereum side of a bridge:
- Using public networks (predefined configs use Kovan testnet and Sokol POA testnet)
Development mode
- Home chain - it keeps an ERC20 contract (
0xd5fE0D28e058D375b0b038fFbB446Da37E85fFdc
) and the bridge contract (0x44c158FE850821ae69DaF37AADF5c539e9d0025B
). - Side chain - the MPC orchestration contract (
0xd5fE0D28e058D375b0b038fFbB446Da37E85fFdc
) is located here Both chains are run in separate docker containers.
Staging mode
Two EVM-based public chains will be used:
- Home chain - Kovan testnet keeps an ERC20 contract and the bridge contract.
- Side chain - Sokol POA testnet keeps the MPC orchestration contract. Interaction with chains is done by using public available RPC urls.
Three validators will be run and only two validators are required to confirm the transfer. Every validator node is a set of docker containers (
eth-watcher
, bnc-watcher
, signer
, proxy
, redis
, rabbitmq
).The public Binance Chain testnet will keep a BEP2 token.
- 1.Preparation
- (1.2) Create a new account through the web-interface in the Binance testnet wallet. Copy the private key and mnemonic phrase. The private key will be used to import it in an Ethereum Wallet. The mnemonic phrase is to recover the BNB with
tbnbcli
. - (1.3) Recover the account in the console with the mnemonic../tbnbcli keys add test_account1 --recover
- (1.4) Create few BNB accounts from the console. They will be donors to provide enough funds to issue a BEP2 tokens (500 BNB required)../tbnbcli keys add test_account2./tbnbcli keys add test_account3
- (1.6) Re-arrange funds on the accounts as so the first account will have 550 BNB and others 10-20 BNBs to make transactions../tbnbcli send --from test_account2 --to <address of the first account> \--amount 18500000000:BNB --chain-id=Binance-Chain-Nile \--node=data-seed-pre-2-s1.binance.org:80 --memo "donate"./tbnbcli send --from test_account3 --to <address of the first account> \--amount 18500000000:BNB --chain-id=Binance-Chain-Nile--node=data-seed-pre-2-s1.binance.org:80 --memo "donate"
- (1.7) Issue the BEP2 token from the first account.
3141500000000000
corresponds to31415000.0
tokens../tbnbcli token issue --token-name "ERC20toBEP2Bridge" --total-supply 3141500000000000 \--symbol ETB0819 --mintable --from test_account1 --chain-id=Binance-Chain-Nile \--node=data-seed-pre-2-s1.binance.org:80 --trust-nodeIn the real deployment most probably the token must not be mintable. - (1.8) Get the BEP2 token ID in
denom
field (in this example it isETB0819-863
)../tbnbcli account <address of the first account> \--chain-id=Binance-Chain-Nile --node=data-seed-pre-2-s1.binance.org:80 --trust-node - (1.9) Clone the repo and initialize git submodules:git clone --recurse-submodules https://github.com/k1rill-fedoseev/eth-to-bnc-bridge.git
- (1.10) Build TSS to be used in the bridge oracles:docker build -t tss -f ./src/tss/Dockerfile-local ./src/tss
- 2.Run test environment
- 2.1 Running in development mode (using local ganache networks):
- (2.1.1) Modify
src/deploy/deploy-test/.env.development
and specify the amount of tokens to mint in the parameterTOKEN_INITIAL_MINT
. - (2.1.2) Run testnets and deploy contractsTARGET_NETWORK=development ./demo/start-environment.shThis command will also mint tokens, the owner of tokens is the address that corresponds to the private key specified in
HOME_PRIVATE_KEY
ofsrc/deploy/deploy-test/.env.development
(0xA374DC09057D6B3253d04fACb15736B43fBc7943
).
- 2.2 Running in staging mode (using public test networks):
- (2.2.1) Prepare three private keys for validators. Get the Ethereum account addresses for these keys.
- (2.2.2) Modify
src/deploy/deploy-home/.env.staging
and specify the token contract address in the Kovan network viaHOME_TOKEN_ADDRESS
(use empty address0x
if you want to create new ERC20 contract while deployment). SetVALIDATOR_ADDRESS_*
to Ethereum addresses obtained in the previous step. - (2.2.3) Modify
src/deploy/.keys.staging
and specify private keys for prefunded accounts in both networks. These accounts are used for contract deployment. Usesrc/deploy/.keys.staging.example
as an example. - (2.2.4) Deploy contractsTARGET_NETWORK=staging ./demo/start-environment.shThis command will deploy ERC20 contract and also mint tokens if you left
HOME_TOKEN_ADDRESS
empty, the owner of tokens is the address that corresponds to the private key specified inHOME_PRIVATE_KEY
ofsrc/deploy/.keys.staging
. Deployed contract address will be automatically updates in all required validators and test services configs. - (2.2.5) Prefund validator accounts in home network (Kovan):TARGET_NETWORK=staging ./src/test-services/ethereumSend/run.sh <Nth validator address> 0 0.5
- (2.2.6) Prefund validator accounts in side network (Sokol):TARGET_NETWORK=staging ./src/test-services/sidePrefund/run.sh <Nth validator address> 1
- (2.3) Get the Ethereum account address for the first test account from its private key (step 1.2). NiftyWalletcould be used for this.
- (2.4) Send few tokens and coins from the current token owner to the first account. Coins are needed to pay transaction fees.TARGET_NETWORK=<target network> ./src/test-services/ethereumSend/run.sh <first account Ethereum address> 5000000000000000000 0.5
- (2.5) Check that the tokens were transferred properly:TARGET_NETWORK=<target network> ./src/test-services/ethereumBalance/run.sh <first account Ethereum address>
- 3.Run validators nodes:
- (3.1) Modify the parameter
FOREIGN_ASSET
indemo/validator1/.env.<network>
,demo/validator2/.env.<network>
anddemo/validator3/.env.<network>
to specify the identificator of the token (step 1.8) that the oracle will watch. For staging environment additionally specifyVALIDATOR_PRIVATE_KEY
in thedemo/validator<N>/.keys.staging
(step 2.2.1) - (3.2) Run three validators in separate terminal sessions.N=1 TARGET_NETWORK=<network> ./demo/validator-demo.shN=2 TARGET_NETWORK=<network> ./demo/validator-demo.shN=3 TARGET_NETWORK=<network> ./demo/validator-demo.shWait for when the line like the following appears:keygen_1 | Generated multisig account in binance chain: tbnb1mutgnx9n9devmrjh3d0wz332fl8ymgel6tydx6The line contains the address of the bridge address in the Bincance Chain.
- 4.Initialize the state of the bridge account in the Binance Chain
- (4.1) Fill the balance Fund with BNB coins as so the account will be able to make transactions:./tbnbcli send --from test_account1 --to <address of the bridge account> \--amount 1000000000:BNB --chain-id=Binance-Chain-Nile \--node=data-seed-pre-2-s1.binance.org:80 --memo "initialization"
- (4.2) Fund the account with bridgeable tokens. This transaction should have 'funding' in the memo:./tbnbcli send --from test_account1 --to <address of the bridge account> \--amount 3141500000000000:ETB0819-863 --chain-id=Binance-Chain-Nile \--node=data-seed-pre-2-s1.binance.org:80 --memo "funding"The oracles should catch this transaction but will ignore it:bnc-watcher_1 | Fetching new transactionsbnc-watcher_1 | Sending api transactions requestbnc-watcher_1 | Found 1 new transactionsTo check the balance of the bridge account the Binance Testnet Explorer could be used. It should report about two assets owned by the account.
- 5.Transfer tokens from Ethereum-based chain to the Binance Chain:
- (5.1) Modify the parameter
HOME_PRIVATE_KEY
(insrc/test-services/ethereumSend/.env.development
orsrc/test-services/.keys.staging
) as so it contains the private key of the first test account (step 1.2) - (5.2) Send some amount of tokens to the bridge contract:TARGET_NETWORK=<network> ./src/test-services/ethereumSend/run.sh bridge 5000000000000000000
- (5.3) The validators will catch the event and start the process to sign the transaction.
- (5.4) As soon as the signature is generated and sent, the balance of the bridge account in both chains will be changed:TARGET_NETWORK=<network> ./src/test-services/ethereumBalance/run.sh 0x94b40CC641Ed7db241A1f04C8896ba6f6cC36b85should report non-zero balance./tbnbcli account <address of the bridge account> \--chain-id=Binance-Chain-Nile --node=data-seed-pre-2-s1.binance.org:80 --trust-nodeshould report about the balance reduction. The balance and transactions related to the bridge account in the Binance Chain could be checked in Binance Testnet Explorer.
- (5.5) Check that the tokens was transferred to the first test account either by
tbnbcli
or by Binance Testnet Explorer.
- 6.Transfer tokens from the Binance Chain to Ethereum-based chain:
- ./tbnbcli send --from test_account1 --to <address of the bridge account> \--amount 300000000:ETB0819-863 --chain-id=Binance-Chain-Nile \--node=data-seed-pre-2-s1.binance.org:80 --memo "any note"
- Check the balances of the test account on both sides of the bridge to see that the funds were transferred properly.
- 7.Bridge supports changing the list of validators and required voting threshold via voting process, and then keys regeneration.
- (7.0) Obtain information about current epoch, current list validators, upcoming epoch information, bridge state via:./curl http://localhost:$PORT/infoWhere
$PORT
is specific port for some validator oracle. The response object contains lots of useful information about current bridge state.{// current epoch number, in which bridge is operating"epoch": 2,// next epoch number, for which votes and keygen operations are applied"nextEpoch": 3,// threshold number for current epoch,// threshold + 1 votes are required for any changes in next epoch"threshold": 1,// threshold number for next epoch"nextThreshold": 1,// current bridge addresses in home and foreign networks"homeBridgeAddress": "0x44c158FE850821ae69DaF37AADF5c539e9d0025B","foreignBridgeAddress": "tbnb19z22khee969yj05dckg9usvmwndkucpyl543xk",// current set of validators"validators": ["0x99Eb3D86663c6Db090eFFdBC20510Ca9f836DCE3","0x6352e3e6038e05b9da00C84AE851308f9774F883"],// set of validators for the next epoch"nextValidators": ["0x99Eb3D86663c6Db090eFFdBC20510Ca9f836DCE3","0x6352e3e6038e05b9da00C84AE851308f9774F883","0xAa006899B0EC407De930bA8A166DEfe59bBfd3DC"],// balances of bridge in both networks"homeBalance": 50,"foreignBalanceTokens": 100,"foreignBalanceNative": 0.0994,// current bridge status, can be one of: ready, voting, keygen, funds_transfer"bridgeStatus": "ready",// current votes count for starting voting, starting/cancelling keygen// -1 means that enough confirmations are already collected"votesForVoting": 0,"votesForKeygen": 0,"votesForCancelKeygen": 0,// collected confirmations for changing epoch to nextEpoch// -1 means that enough confirmations are already collected"confirmationsForFundsTransfer": 0} - (7.1) Start voting process for next epoch, via sending
$THRESHOLD + 1
requests to/vote/startVoting
url. Bridge state should be successfully changed tovoting
. - 7.2 Changing next epoch bridge validators / threshold
- (7.2.1) Add / remove validator in next validators list, via sending
$THRESHOLD + 1
requests to/vote/addValidator/$ADDRESS
//vote/removeValidator/$ADDRESS
. - (7.2.2) Change threshold for the next epoch, via sending
$THRESHOLD + 1
requests to/vote/changeThreshold/$THRESHOLD
.
- (7.3) Start keygen process for next epoch, via sending
$THRESHOLD + 1
requests to/vote/startKeygen
url. Bridge state should be successfully changed tokeygen
, and in some time tofunds_transfer
, and then toready
. - (7.4) If keygen process at some state was stopped(i. e. one validator turned of his oracle), it can be cancelled via via sending
$THRESHOLD + 1
requests to/vote/cancelKeygen
url. After keygen cancellation, bridge state will return tovoting
, and later it can be restarted manually once again.
- 1.Stop all validator instances by pressing
^C
in the terminal. - 2.Stop the local testnets:docker kill ganache_homedocker kill ganache_side
- 3.Remove virtual networks:docker network rm blockchain_homedocker network rm blockchain_sidedocker network rm validator1_test_networkdocker network rm validator2_test_networkdocker network rm validator3_test_network
- 4.Remove testnets and validators data:TARGET_NETWORK=<network> ./demo/clean.sh
Testing tools for both sides of the bridge
In these tools,
run.sh
file simply builds and runs a docker container for interacting with test blockchains. Every tool contains the file .env
where parameters (RPC urls and private keys) are kept../src/test-services/binanceSend/run.sh TO TOKENS NATIVE
- Sends specified amount of tokens and BNBs to the bridge account.
TO
- receiver address in the Binance Chain.TOKENS
- amount of tokens to send.NATIVE
- amount of BNB tokens to send, if present, the transaction is considered as a funding one.
./src/test-services/ethereumSend/run.sh TO TOKENS NATIVE
- Transfers specified amount of tokens and coins to the an Ethereum account on the home network.
TO
- receiver address in the Ethereum-based chain, specifybridge
to send tokens to the bridge address.VALUE
- amount of tokens to transfer and exchange.NATIVE
- amount of coins to send (inether
). Could be omitted.
./src/test-services/sidePrefund/run.sh TO NATIVE
- Transfers specified amount of tokens and coins to the an Ethereum account on the side network.
TO
- receiver address in the Ethereum-based chain.NATIVE
- amount of coins to send (inether
). Could be omitted.
./src/test-services/binanceBalance/run.sh ADDRESS
(it is recommended to usetbnbcli
instead)- Gets current BEP2 token and BNB balances of the specified account.
ADDRESS
- account address in the Binance Chain.
./src/test-services/ethereumBalance/run.sh ADDRESS
- Gets current ERC20 token balance of the specified account.
ADDRESS
- Ethereum address of the account.
Interacting with validators, sending votes, retrieving bridge information
- For each validator, a specific port is mapped outside of the docker container for listening GET requests
- 5001 - first validator
- 5002 - second validator
- 5003 - third validator
- Retrieving bridge state
- Voting for bridge state changes
- After enough votes are collected, keygen process starts, and ends with the transfer of all remained funds in the Binance Chain to the new generated bridge account.
ADDRESS
- Ethereum address of a validator.- After enough votes are collected, validator is added into the next validators list for the next epoch.
ADDRESS
- Ethereum address of a validator.- After enough votes are collected, validator is removed from the next validators list for the next epoch.