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Side chain setup (Import Gateway CC)
Creating side chain for a coin is able on Komodo asset chains using import gateway CC. The external coin can be any bitcoin protocol chain (you cannot use ETH or any other coins which is not on bitcoin protocol for now). It works by locking coins on external chain in a multi signature address (it can be a normal address with single private key but then this would not be decentralized and trust woud be in a single point which can be corrupt) and giving the same amount of coins in asset chain. So now you can operate on this side chain, use all of the features in Komodo ecosystem and when you don't want to be on side chain anymore you can withdraw the amount of coins you have and get them back in original chain. In all examples here I will use KMD chain as external chain for which we will create side chain. Everything can be created using TUI (text UI) which is faster but in this wiki I will explain how to do it manually.
There are steps that needs to be done to prepare your nodes for the setup. They are not all necessary to be done before but usually I forgot some of them so the best time is to do it in the beginning. You will need N nodes which have to run both external chain nodes and AC nodes.
If you want to test how side chain works, you need to compile all nodes in test mode so that you do not need to wait long for tx confirmations or to have notarization enabled on your AC chain. You need to do the following before build:
export CONFIGURE_FLAGS='CPPFLAGS=-DTESTMODE'
./zcutil/build.sh
To create a chain that will use import gateway CC you must supply following ac parameters: -ac_import=<external_coin_name> -ac_supply=<initial_supply_necessary_for_setup> -ac_reward=1 -ac_end=1 -ac_perc=0. Initial supply of coins will be given to node which is started with -gen=1 and you will use those coins to setup oracle and import gateway. After that the rest can be burnt (sent to unspendable address) if you want.
komodod -ac_name=KMDSIDECHAIN -ac_cc=2 -ac_import=KMD -ac_supply=100 -ac_reward=1 -ac_end=1 -ac_perc=0
On the nodes which will be in charge of deposit and withdraw and sign the multi signature address they must have both external chain node and AC node running. You need to have fully synced external chain.
After creating a AC and syncing external chain, you need to dump the private keys of AC signing nodes and import them to external chain nodes.
komodo-cli -ac_name=KMDSIDECHAIN dumpprivkey "nodes_pubkey_address"
komodo-cli importprivkey "private_key "label" false
You need to create a oracle for submitting external chain block data. Oracle must have the same name as external coin (in this example KMD), and Ihh format.
komodo-cli -ac_name=KMDSIDECHAIN oraclescreate KMD kmd_block_data Ihh
On all signing nodes you must register as publisher with data fee and subscribe on your self to be able to post block data. Data fee can be whatever as publishers get paid from subscribe a data fee, but as you will subscribe on your self it will pay you from your subscribe (usually I use 10k sat). It is recommended to do more than one subscribe as it will dictate how many external block data you can submit in each AC block. Also subscribe with enough amount to be able to pay yourself (I usualy subscribe in few coins on 10k sat data fee)
komodo-cli -ac_name=KMDSIDECHAIN oraclesfund <oraclescreate_txid>
komodo-cli -ac_name=KMDSIDECHAIN oraclesregister <oraclescreate_txid> 10000
komodo-cli -ac_name=KMDSIDECHAIN oraclessubscribe <oraclescreate_txid> <publishers_pubkey> 10
...
komodo-cli -ac_name=KMDSIDECHAIN oraclessubscribe <oraclescreate_txid> <publishers_pubkey> 10
Now it is time to create a import gateway. You need to supply external coin name (and it needs to match oracles name too), oracles create txid, then you need to define MofN multi signature type, supply all N pubkeys and supply pubkey, p2sh and wif types.
komodo-cli -ac_name=KMDSIDECHAIN importgateway KMD <oraclescreate_txid> 2 3 <pubkey1> ... <pubkeyN> 60 85 188
Now that we have import gateway created, we need to start the nodes with -earlytxid parameter in order to have only one valid importgateway that can operate on chain. Imagine if we don't do this and allow everybody to create it's own import gateway and issue coins on chain and they make 1of1 gateway so they can steal your deposit.
NOTE: all these steps must be done before block 100 as earlytxid will not accept importgatewaybind tx after block 100
komodo-cli -ac_name=KMDSIDECHAIN -ac_cc=2 -ac_import=KMD -ac_supply=100 -ac_reward=1 -ac_end=1 -ac_perc=0 -earlytxid=<importgatewaybind_txid>
Lets now run oraclefeed dapp on every node of N created nodes. Compile oraclefeed from komoodo source:
gcc cc/dapps/oraclefeed.c -lm -o oraclefeed -g
You need to supply coin name, oracle txid, node pubkey, oracle format and importgatwaybind on each node.
oraclefeed KMD <oraclescreate_txid> <node_pubkey> Ihh <importgatewaybind_txid>
NOTE: if external chain is not from Komodo ecosystem then you need to additionally supply path to cli executable as last parameter to oraclefeed
At this point the side chain should be properly configured. You can test the deposit and withdraw of coins to make sure everything works
To deposit coins you must make a tx on external chain with sending coins to import gateway deposit address along with a small amount as a marker to address that belongs to pubkey that will receive deposited coins on AC but in external chain address format. Check what is the deposit address with komodo-cli -ac_name=KMDSIDECHAIN importgatewayinfo <importgatewaybind_txid> and to get the address for receivers pubkey use komodod -ac_name=KMDSIDECHAIN importgatewayexternaladdress <impotgatewaybind_txid> <pubkey>
Now that you have all addresses needed use the rpc to send funds to multiple addresses on external chain. In our example we will deposit KMD to get KMDSIDECHAIN coins:
komodo-cli z_sendmany "address_where_KMD_funds_are_currently_held" '[{"address":"address_of_receiver_pubkey","amount":0.0001},{"address":"importgateway_deposit_address","amount":0.1}]'
You need to wait the tx to be mined on external chain and take a note of the tx block height. Next, we need to make sure that the block where our deposit tx is enters into oracle of block data. You can check latest 5 heights with:
komodo-cli -ac_name=KMDSIDECHAIN oraclesinfo <oraclescreate_txid>
komodo-cli -ac_name=KMDSIDECHAIN oraclessamples <oraclecreate_txid> <baton_address> 5
If the height is greater than deposit height, or you see that height in those 5 samples it means that it is submitted to oracle. Before we can do importgatewaydeposit tx you must get some info that you will need to supply to the tx. You will need raw hex of deposit tx and the proof:
komodo-cli getrawtransaction <deposit_txid>
komodo-cli gettxoutproof '["<deposit_txid>"]'
Now lets do the importgatewaydeposit:
komodo-cli -ac_name=KMDSIDECHAIN importgatewaydeposit <importgatewaybind_txid> <deposit_tx_height> KMD <deposit_txid> 0 <raw_hex> <proof> <receivers_pubkey> 0.1
When the importgatewaydeposit tx is mined the receiver should receive the deposited amount in KMDSIDECHAIN coins.