A Modified Smart Contract Execution Enviroment for Safe Function Calls

Abstract

When a Solidity smart contract has a problem in calling a function of another contract, the "fallback function" of the contract is supposed to be executed automatically. However, in many cases, a fallback function is arbitrarily created and called, with their behaviors unknown to developers, so that its execution is vulnerable to exploits by attackers. To reduce these risks, this paper proposes a method that provides developers with new keywords by modifying existing Solidity compiler and Ethereum Virtual Machine (EVM). Developers mark their intention using the newly introduced keywords, and the modified existing Solidity compiler and EVM uses flags and conditional statements to prevent calls of fallback functions to reduce the risk of calls to fallback functions.