EVM Precompiles

Precompiles are special contracts accessible at fixed addresses that execute native runtime logic instead of EVM bytecode. They allow EVM clients — including MetaMask and other Ethereum wallets — to interact directly with Substrate pallets and cryptographic primitives without needing a custom JSON-RPC endpoint.

Orbinum exposes three groups of precompiles: Ethereum standard precompiles, Frontier non-standard precompiles, and Orbinum-specific precompiles.

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Address Convention

Precompile addresses follow the Frontier convention:

H160::from_low_u64_be(n)

where n is a small integer. This produces an address of the form 0x0000000000000000000000000000000000000NNN.

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Ethereum Standard Precompiles

These are the precompiles defined in the Ethereum Yellow Paper and its EIPs. They are available at the same addresses as Ethereum mainnet.

Address	Name	Description
0x0000000000000000000000000000000000000001	ECRecover	ECDSA signature recovery
0x0000000000000000000000000000000000000002	SHA-256	SHA-2 256-bit hash
0x0000000000000000000000000000000000000003	RIPEMD-160	RIPEMD 160-bit hash
0x0000000000000000000000000000000000000004	Identity	Data copy (identity function)
0x0000000000000000000000000000000000000005	Modexp	Modular exponentiation (EIP-198)

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Frontier Non-Standard Precompiles

These precompiles are provided by Frontier for Substrate-based chains. They are not part of the Ethereum standard and are only available on Frontier-compatible networks.

Address	Name	Description
0x0000000000000000000000000000000000000400	SHA3-FIPS-256	FIPS 202-compliant Keccak-256
0x0000000000000000000000000000000000000401	ECRecoverPublicKey	ECDSA public key recovery
0x0000000000000000000000000000000000000402	Curve25519Add	Curve25519 point addition
0x0000000000000000000000000000000000000403	Curve25519ScalarMul	Curve25519 scalar multiplication

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Orbinum Precompiles

These precompiles expose Orbinum-specific runtime pallets to EVM clients. They are deployed in the 0x0800–0x08FF range to avoid collisions with standard and Frontier precompiles.

Address	Name	Description
0x0000000000000000000000000000000000000800	AccountMapping	Link EVM and Substrate accounts
0x0000000000000000000000000000000000000801	ShieldedPool	Shield, transfer, and unshield tokens using ZK proofs

Address Derivation

Orbinum precompile indices map as follows:

Index	Hex Address
2048 (0x800)	0x…0000000000000000000000000000000000000800
2049 (0x801)	0x…0000000000000000000000000000000000000801

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Calling a Precompile

From Solidity:

interface IShieldedPool {
    function shield(
        uint32 assetId,
        uint256 amount,
        bytes32 commitment,
        bytes calldata encryptedMemo
    ) external;
}

IShieldedPool pool = IShieldedPool(0x0000000000000000000000000000000000000801);
pool.shield(0, 1e18, commitment, memo);

From ethers.js:

import { ethers } from "ethers";

const abi = ["function shield(uint32,uint256,bytes32,bytes)"];
const precompile = new ethers.Contract(
  "0x0000000000000000000000000000000000000801",
  abi,
  signer
);
await precompile.shield(0, ethers.parseEther("1"), commitment, memo);

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Security Notes

• Orbinum precompiles use AddressMapping to derive the caller's AccountId32 from the EVM H160 sender. No signature verification is repeated inside the precompile — the EVM transaction already provides authentication.
• Precompiles do not return values beyond a success indicator. Use RPC or events to confirm state changes.
• Gas costs are estimated conservatively. They may be adjusted before mainnet.