The EVM CoreISSUE #17 of 48

precompiles · ecrecover · modexp · pairings

SoliaVSThe Reentrancy Reaper

Solia saysPrecompiles are pseudo-contracts at addresses 0x01-0x09 that expose expensive primitives (ecrecover, modexp, pairings) at gas costs the EVM could not afford to implement in bytecode.

Precompiles are special addresses that execute native code instead of EVM bytecode. They exist because primitives like ecrecover or BN254 pairings are far too expensive to run as Solidity — they need native crypto. The fixed addresses 0x01-0x09 cover signature recovery, hashes (SHA-256, RIPEMD-160), identity (memcpy), modular exponentiation, elliptic-curve add/mul, pairings, and BLAKE2.

You invoke them like any other contract — usually via staticcall or assembly. Gas costs are bespoke: ecrecover is 3,000 flat, modexp depends on input sizes, pairings cost 100,000+ per pairing. Knowing which precompile exists is the difference between an unwritable contract and a one-line call.

Power-ups you unlock

Pseudo-contracts at 0x01-0x09 with native implementations
Expose primitives too expensive for EVM bytecode
Cover ecrecover, hashes, identity, modexp, BN254 ops, pairings, BLAKE2
Called like normal contracts via staticcall
Costs are bespoke per precompile (often size-dependent)

The Reentrancy Reaper attacks — common mistakes

Reimplementing ecrecover in Solidity (thousands more gas)
Forgetting precompiles can revert (e.g., invalid signature)
Hardcoding gas to a precompile without accounting for input size
Confusing precompile addresses with regular EOAs

Boss battleList the precompile addresses, their primitives, and approximate gas costs.

Example code

<!doctype html><html><head><meta charset="utf-8"></head>
<body style="background:#06040d;color:#e6e0ff;font-family:monospace;padding:20px"><pre id="o"></pre>
<script>
const precompiles = [
  { addr:'0x01', name:'ecrecover',  gas:'3000',    use:'recover signer from ECDSA sig' },
  { addr:'0x02', name:'sha256',     gas:'60+12/w', use:'SHA-256 hash' },
  { addr:'0x03', name:'ripemd160',  gas:'600+120/w', use:'RIPEMD-160 hash' },
  { addr:'0x04', name:'identity',   gas:'15+3/w',  use:'memcpy (input → output)' },
  { addr:'0x05', name:'modexp',     gas:'variable', use:'modular exponentiation' },
  { addr:'0x06', name:'ecadd',      gas:'150',     use:'BN254 point addition' },
  { addr:'0x07', name:'ecmul',      gas:'6000',    use:'BN254 scalar mul' },
  { addr:'0x08', name:'ecpairing',  gas:'45000+34000/pair', use:'BN254 pairing check' },
  { addr:'0x09', name:'blake2f',    gas:'variable', use:'BLAKE2b F compression' }
];
document.getElementById('o').textContent = [
  'precompiled contracts (native, faster than EVM):',
  '  ' + 'addr'.padEnd(6) + 'name'.padEnd(12) + 'gas'.padEnd(24) + 'use',
  ...precompiles.map(p => '  ' + p.addr.padEnd(6) + p.name.padEnd(12) + p.gas.padEnd(24) + p.use),
  '',
  'called with staticcall; revert on invalid input'
].join('\n');
</script></body></html>

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