Verifying deployed bytecode against executable EVM semantics, with exact gas and no added axioms

Seulkee Baek

Much of Ethereum's most consequential code is immutable bytecode: old output of unverified compilers, and protocol logic run as contract code. We show that such bytecode can be verified as it is, without trusting what produced it, without simplifying the machine it runs on, and with no axioms beyond Lean's own. Blanc, a Lean 4 verification stack, reads fixed runtime bytes via kernel-checked certificates and states every theorem against Jaune, an executable semantics of the EVM and block processing that passes all 34,205 blockchain-test cases of Ethereum's fixture release v20.0.2 that involve only forks that have governed mainnet since May 2025. Eight artifacts, deployed from 2017 to 2026, come from seven compiler versions and an assembler. For the EIP-7002 contract, we prove that the end-of-block call to it, whose failure would invalidate the block, succeeds whatever its storage holds, and that each block's withdrawal requests are exactly the oldest pending submissions; mainnet met these theorems' starting premises when Prague began. For a Uniswap V2 pair, we prove that after any valid history whose hashed slots stay apart, from any checkpoint representing its Solidity model's…