Migrating Smart Contracts from Ethereum to BNB Smart Chain

Motivation

Many growing chains like BNB Smart Chain want to attract, onboard, or switch customers and developers to their growing ecosystem. They need tools and technologies to assist and guide interested users in moving their smart contracts to their systems with ease, reliability, and speed.

As an interesting example case, since Ethereum blockchain gas prices continue to rise,  smart contract owners are seeking alternatives that offer better performance and lower costs. This is a great opportunity for BNB to offer BNB Smart Chain (BSC) as a promising alternative and to become a popular choice and destination for to-be-migrated smart contracts.

When a smart contract is migrated, both its source code and state variables are transferred to the new chain. Bridges can help migrate token assets, but the transfer of other states and data can take several days. Non-token smart contracts, such as decentralized applications (Dapps), often do not utilize bridge or wallet services and require manual migration.

Advantages
SmartMuv offers an automatic migration solution to address the above requirements and needs  that can move smart contracts and their complete state within seconds across EVM-compatible chains. This is done in an automatic, easy, and verifiable way where the entire data is correctly extracted and deployed reliably.

Migration of Smart Contract from Ethereum to BSC Testnet

To demonstrate the feasibility and functionality of SmartMuv, we show the results of successful migrations of three smart contracts from the Ethereum Mainnet to the BNB Smart Chain Testnet. The migration process takes 4-5 minutes for state extraction and deployment to another blockchain, as the complete process is automatic. The time taken can vary as it depends upon the total number of transactions of the smart contract and the size of the extracted state.
The SmartMuv migration process consists of the following steps.
 
State Analysis

In the initial stage, we are provided with the source code, name, and address of the smart contract, which is subject to analysis using our algorithm to identify and extract all relevant data. The screenshots of the analysis are shown below.

State Extraction of Smart Contracts

Following the analysis's completion, the smart contract's state is extracted from the Ethereum blockchain up to the latest block (16,639,365). This extracted state is then displayed, with the appropriate association to their corresponding state variables, as depicted in the screenshot below:

State Packing

After the state extraction, the next step is to pack and download the complete state of the smart contract by clicking on the ‘Pack’ button.
 The complete extracted states of all three smart contracts are available here.

Deployment to BSC Testnet

We proceeded with the migration process by utilizing our migration adapter to transfer the state to the BSC Testnet. The steps of migration are as follows:
● Smart contract with additional ‘initializeContract’ method is deployed.
● After deployment we pass the migration data to ‘initializeContract’ method that writes the data of every variable on the storage.
 
The addresses of each contract in the Ethereum blockchain and on the BSC Testnet after the migration are provided in the table below.
 

Migration state size and cost

Following the smart contract migration, we calculated the corresponding gas cost and prices in both USD dollars and BNB. These calculations were based on the migrated state size of the three smart contracts, and the results are presented below:

Verification of Migrated States

It is essential to perform verification after the smart contract migration process. This verification involves comparing the state of the smart contract on both Ethereum Mainnet and BSC Testnet. We verified our migration as well as extraction of the smart contract on BSC Testnet in the following way:

Method # 1

To validate the state of the migrated smart contract on BNB Smart Chain Testnet, we used methods like ‘balanceOf’ and ‘allowance’ to check each entry of ‘balance’ and ‘allowed’ mappings, and also checked values of other state variables. This allowed us to confirm that the state of the migrated smart contract on the BNB Smart Chain Testnet is consistent with the state on the Ethereum Mainnet.
 
The details of migrated keys and balance values of all three smart contracts are available here.

Method # 2

To conduct a more thorough verification of the smart contract migration process, we carried out additional tests to ensure the migrated smart contract was functioning correctly on BNB Smart Chain Testnet.
For this, we used the ‘DecalincCoin’ smart contract and modified its recipient address for balance equivalent to ‘total_supply’ in the constructor to ‘0x61B3A112665968d2D286a473E7A783749F7aB69f’. We also changed the state using the ‘transfer’ function and performed the following transfer operations:
● transfer(0x937061586a8ed07Fd82d942fb9Ce16cdBBD1bC50, 450000)
● transfer(0x3Fe71A87336C64fa499ebF821266FD3A4E5e9150, 999999)
● transfer(0x03beb60790fd3F3A114d9Ba864689513718347Cd, 3200000)
 
Prior to these operations, the assigned balance of the address was 1000000000000000000000000000. After the operations, the balance should have been reduced to 999999999999999999995350001, and there should have been three additional balance keys other than the migrated data.
We then extracted the state of the contract and compared it to the expected results, which confirmed the effectiveness of our state extraction technique on the BNB Smart Chain Testnet
The extracted state (without migrated data) on the BSC Testnet after the above changes are given below: