evm-leaf-verify

Minimal keccak256 + typed-data leaf helpers for EVM signature forensics. Dependency-free, pure BigInt, no build step. Written for audit repros where pulling in ethers just to hash a leaf is overkill.

const v = require("evm-leaf-verify");

v.keccak256hex("0x1901...");   // keccak of hex/utf8, 0x-hex out
v.leafHash("0x...");           // double-keccak merkle leaf (OZ encoding)
v.digest712(domainSep, struct); // keccak256(0x1901 || sep || structHash)
v.lookupDigest("0x...");       // check the observed-digest table

Observed-digest table

lookupDigest checks a digest against a table of digests observed on public gateway streams (test envs, staging signers). A hit means the same payload has been seen signed before - useful context when reproducing a capture.

The table grows faster than the lib, so the full copy ships as a data release (tables) on this repo and is refreshed into a local cache in the background, the same way CLI update-checkers work. First run or offline, a small builtin table is used instead. Set ELV_TABLES_URL to use a mirror. Nothing here is required for the hashing helpers; they never touch the network.

Not constant-time. Audit/research use only.