How Does the Concept of ‘Invariants’ Relate to the Security of Financial Smart Contracts?

An invariant is a condition or property that must always remain true throughout the entire lifecycle and execution of a smart contract, regardless of any transaction. For a financial contract, an invariant might be "the sum of all user balances must equal the total supply" or "no user can withdraw more than their deposited amount." If an invariant is violated, it signals a critical bug or security breach.

Security measures, including formal verification, are often designed to prove that these financial invariants can never be broken.