Fig. 2
From: Detecting DeFi securities violations from token smart contract code
DApp creation and functioning. The first box contains an excerpt from the Solidity code for the exchange function of the popular dex Uniswap. The second box shows the same code compiled into EVM-readable bytecode. The third box shows the transaction that deployed this code to the Ethereum blockchain, thereby creating the dApp. The branch of Fig. 2 labelled “front-end” shows Uniswap’s user interface for a sample exchange operation of 645.49035 USDT to ETH. Below the exchange interface is a screenshot of the Web3 wallet MetaMask. To execute a transaction like the exchange depicted above, the user must connect their Web3 wallet to the relevant dApp via the wallet’s browser extension. From there, they can approve the transaction. After the transaction is executed, the user’s MetaMask wallet automatically reflects the new balances of these cryptocurrencies. On the back-end, the aforementioned exchange takes the form of bytecode (depicted on the “back-end” branch of the figure), which is executed by the EVM. The final box shows the hash of the executed transaction exchanging USDT for ETH. Full details of this exchange can be found at https://etherscan.io/tx/0x7febc16c960a177077ddf0562c9ba21ac9bd5585bacf969d88a6b678e756081a. The full Solidity source code for the Uniswap V2 smart contract can be found at https://etherscan.io/address/0x7a250d5630b4cf539739df2c5dacb4c659f2488d#code