Skip to content

Latest commit

 

History

History
71 lines (56 loc) · 13.4 KB

evm.md

File metadata and controls

71 lines (56 loc) · 13.4 KB
Raw

Evm Module

Bitgreen provides and EVM execution module that allows unmodified EVM code to be executed in Bitgreen blockchain (Substrate based).

There are a separate set of accounts managed by the EVM module. Substrate based accounts can call the EVM Module to deposit or withdraw balance from the Substrate base-currency into a different balance managed and used by the EVM module. Once a user has populated their balance, they can create and call smart contracts using this module.
There's one-to-one mapping from Substrate accounts and EVM external accounts that is defined by a conversion function.
Here an utility to convert the Substrate Account to Ethereum.

Managing Ethereum Balances

Two operations are possible: we can "deposit" funds from a Substrate account into its corresponding Ethereum account, and we can "withdraw" funds from an Ethereum account back into the source Substrate account.

Deposits

Since the EVM address backing an Ethereum address is computed determinstically, as above, we can perform a standard balance transfer from our source Substrate account to the EVM address in order to seed the Ethereum account with funds.
This can be performed by calling balances::transfer(prefixAndHash(truncate(account)).signAndSend(account), where account is the source substrate account, truncate takes the first 20 bytes as the Ethereum address, and prefixAndHash applies the evm: prefix and takes the hash as to convert back into a 32-byte Substrate address.

Withdrawal

Since the EVM address is computed deterministically, we do not have a private key for it, so we cannot perform a balance transfer from it via normal means. As a result, the EVM module provides a special function withdraw for transferring funds back from an Ethereum account to the source Substrate account.
This can be performed by calling evm::withdraw(truncate(account), value).signAndSend(account) where account is the source Substrate account, and truncate takes the first 20 bytes as the Ethereum address.

Ethereum Balances

Ethereum balances are handled as if they were running on any Ethereum chain: gas is subtracted from the balance (the quantity of gas used can be accessed from the transaction receipt returned by the EVM module through web3 or truffle), and transfers work as expected.
The balance of the 20-byte Ethereum address and the 32-byte EVM address should be identical, when compared: web3.eth.getBalance(ethAddress) should equal system::balances(prefixAndHash(ethAddress)).freeBalance, where ethAddress is the 20-byte Ethereum address, and prefixAndHash applies the evm: prefix and takes the hash, as explained above.
Note that the conversion rate of EVM gas to substrate tokens is defined in the Substrate runtime as FeeCalculator, which is set to a 1-to-1 wei-to-Substrate token mapping.
When converting, also note the gasPrice is specified in the EVM call, as the conversion factor from the gasUsed field in the receipt to wei.

Example to create/call a Smart Contract (Solidity Language)

Start the node in development mode:

./target/release/bitgreem-node --dev

Use the UI https://polkadot.js.org/apps to deploy the contract from Alice's account (submit the extrinsic as a signed transaction) using evm > create with the following parameters:

source: 0xd43593c715fdd31c61141abd04a99fd6822c8558
init: 0x608060405234801561001057600080fd5b50610041337fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff61004660201b60201c565b610291565b600073ffffffffffffffffffffffffffffffffffffffff168273ffffffffffffffffffffffffffffffffffffffff1614156100e9576040517f08c379a000000000000000000000000000000000000000000000000000000000815260040180806020018281038252601f8152602001807f45524332303a206d696e7420746f20746865207a65726f20616464726573730081525060200191505060405180910390fd5b6101028160025461020960201b610c7c1790919060201c565b60028190555061015d816000808573ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff1681526020019081526020016000205461020960201b610c7c1790919060201c565b6000808473ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff168152602001908152602001600020819055508173ffffffffffffffffffffffffffffffffffffffff16600073ffffffffffffffffffffffffffffffffffffffff167fddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef836040518082815260200191505060405180910390a35050565b600080828401905083811015610287576040517f08c379a000000000000000000000000000000000000000000000000000000000815260040180806020018281038252601b8152602001807f536166654d6174683a206164646974696f6e206f766572666c6f77000000000081525060200191505060405180910390fd5b8091505092915050565b610e3a806102a06000396000f3fe608060405234801561001057600080fd5b50600436106100885760003560e01c806370a082311161005b57806370a08231146101fd578063a457c2d714610255578063a9059cbb146102bb578063dd62ed3e1461032157610088565b8063095ea7b31461008d57806318160ddd146100f357806323b872dd146101115780633950935114610197575b600080fd5b6100d9600480360360408110156100a357600080fd5b81019080803573ffffffffffffffffffffffffffffffffffffffff16906020019092919080359060200190929190505050610399565b604051808215151515815260200191505060405180910390f35b6100fb6103b7565b6040518082815260200191505060405180910390f35b61017d6004803603606081101561012757600080fd5b81019080803573ffffffffffffffffffffffffffffffffffffffff169060200190929190803573ffffffffffffffffffffffffffffffffffffffff169060200190929190803590602001909291905050506103c1565b604051808215151515815260200191505060405180910390f35b6101e3600480360360408110156101ad57600080fd5b81019080803573ffffffffffffffffffffffffffffffffffffffff1690602001909291908035906020019092919050505061049a565b604051808215151515815260200191505060405180910390f35b61023f6004803603602081101561021357600080fd5b81019080803573ffffffffffffffffffffffffffffffffffffffff16906020019092919050505061054d565b6040518082815260200191505060405180910390f35b6102a16004803603604081101561026b57600080fd5b81019080803573ffffffffffffffffffffffffffffffffffffffff16906020019092919080359060200190929190505050610595565b604051808215151515815260200191505060405180910390f35b610307600480360360408110156102d157600080fd5b81019080803573ffffffffffffffffffffffffffffffffffffffff16906020019092919080359060200190929190505050610662565b604051808215151515815260200191505060405180910390f35b6103836004803603604081101561033757600080fd5b81019080803573ffffffffffffffffffffffffffffffffffffffff169060200190929190803573ffffffffffffffffffffffffffffffffffffffff169060200190929190505050610680565b6040518082815260200191505060405180910390f35b60006103ad6103a6610707565b848461070f565b6001905092915050565b6000600254905090565b60006103ce848484610906565b61048f846103da610707565b61048a85604051806060016040528060288152602001610d7060289139600160008b73ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff1681526020019081526020016000206000610440610707565b73ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002054610bbc9092919063ffffffff16565b61070f565b600190509392505050565b60006105436104a7610707565b8461053e85600160006104b8610707565b73ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002060008973ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002054610c7c90919063ffffffff16565b61070f565b6001905092915050565b60008060008373ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff168152602001908152602001600020549050919050565b60006106586105a2610707565b8461065385604051806060016040528060258152602001610de160259139600160006105cc610707565b73ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002060008a73ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002054610bbc9092919063ffffffff16565b61070f565b6001905092915050565b600061067661066f610707565b8484610906565b6001905092915050565b6000600160008473ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002060008373ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002054905092915050565b600033905090565b600073ffffffffffffffffffffffffffffffffffffffff168373ffffffffffffffffffffffffffffffffffffffff161415610795576040517f08c379a0000000000000000000000000000000000000000000000000000000008152600401808060200182810382526024815260200180610dbd6024913960400191505060405180910390fd5b600073ffffffffffffffffffffffffffffffffffffffff168273ffffffffffffffffffffffffffffffffffffffff16141561081b576040517f08c379a0000000000000000000000000000000000000000000000000000000008152600401808060200182810382526022815260200180610d286022913960400191505060405180910390fd5b80600160008573ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002060008473ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff168152602001908152602001600020819055508173ffffffffffffffffffffffffffffffffffffffff168373ffffffffffffffffffffffffffffffffffffffff167f8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925836040518082815260200191505060405180910390a3505050565b600073ffffffffffffffffffffffffffffffffffffffff168373ffffffffffffffffffffffffffffffffffffffff16141561098c576040517f08c379a0000000000000000000000000000000000000000000000000000000008152600401808060200182810382526025815260200180610d986025913960400191505060405180910390fd5b600073ffffffffffffffffffffffffffffffffffffffff168273ffffffffffffffffffffffffffffffffffffffff161415610a12576040517f08c379a0000000000000000000000000000000000000000000000000000000008152600401808060200182810382526023815260200180610d056023913960400191505060405180910390fd5b610a7d81604051806060016040528060268152602001610d4a602691396000808773ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002054610bbc9092919063ffffffff16565b6000808573ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002081905550610b10816000808573ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff16815260200190815260200160002054610c7c90919063ffffffff16565b6000808473ffffffffffffffffffffffffffffffffffffffff1673ffffffffffffffffffffffffffffffffffffffff168152602001908152602001600020819055508173ffffffffffffffffffffffffffffffffffffffff168373ffffffffffffffffffffffffffffffffffffffff167fddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef836040518082815260200191505060405180910390a3505050565b6000838311158290610c69576040517f08c379a00000000000000000000000000000000000000000000000000000000081526004018080602001828103825283818151815260200191508051906020019080838360005b83811015610c2e578082015181840152602081019050610c13565b50505050905090810190601f168015610c5b5780820380516001836020036101000a031916815260200191505b509250505060405180910390fd5b5060008385039050809150509392505050565b600080828401905083811015610cfa576040517f08c379a000000000000000000000000000000000000000000000000000000000815260040180806020018281038252601b8152602001807f536166654d6174683a206164646974696f6e206f766572666c6f77000000000081525060200191505060405180910390fd5b809150509291505056fe45524332303a207472616e7366657220746f20746865207a65726f206164647265737345524332303a20617070726f766520746f20746865207a65726f206164647265737345524332303a207472616e7366657220616d6f756e7420657863656564732062616c616e636545524332303a207472616e7366657220616d6f756e74206578636565647320616c6c6f77616e636545524332303a207472616e736665722066726f6d20746865207a65726f206164647265737345524332303a20617070726f76652066726f6d20746865207a65726f206164647265737345524332303a2064656372656173656420616c6c6f77616e63652062656c6f77207a65726fa265627a7a72315820c7a5ffabf642bda14700b2de42f8c57b36621af020441df825de45fd2b3e1c5c64736f6c63430005100032  
value: 0  
gas_limit: 4294967295  
gas_price: 1

where:

  • "source" is the EVM address of Alice Account that has been computed using the utility in "evm-utility" folder.
  • "init" is the bytecode of the compiled smart contract. Above is an example of an ERC20 smart contract.
  • "value" simple set to 0.
  • "gas_limit" is the maximum gas your wish to pay.
  • "gas_price" simple set to 1.

From "Explorer" get the address of the contract and use it to make calls, for example we assume the contract address is:

0x43da1e6e044daea62d97f37d467de0eaeb4cdf23

Make a new Extrising using the pallet Evm/Call with the following parameters:

source: 0xd43593c715fdd31c61141abd04a99fd6822c8558  
target: 0x43da1e6e044daea62d97f37d467de0eaeb4cdf23  
input: 0xa9059cbb0000000000000000000000008bc395119f39603402d0c85bc9eda5dfc5ae216000000000000000000000000000000000000000000000000000000000000000dd  
value: 0 
gas_limit: 4294967295  
gas_price: 1
  • "source" is the EVM address of Alice Account that has been computed using the utility in "evm-utility" folder.
  • "target" is contract address.
  • "input" is an EVM ABI-encoded function call that was calculated using the Remix web IDE; it consists of a function selector (0xa9059cbb) and the arguments to be used for the function invocation. In this case, the arguments correspond to Bob's EVM account ID (0x8bc395119f39603402d0c85bc9eda5dfc5ae2160) and the number of tokens to be transferred (0xdd, or 221 in hex).
  • "value" simple set to 0.
  • "gas_limit" is the maximum gas your wish to pay.
  • "gas_price" simple set to 1.