@usekova/evm

EVM anchoring utilities for on-chain covenant verification with ABI encoding and Keccak-256 hashing.

Installation

npm install @usekova/evm

Key APIs

• EVMClient: Client for anchoring and verifying covenants on-chain via a user-supplied JSON-RPC provider. No ethers.js dependency.
• encodeUint256() / decodeUint256(): ABI encode/decode uint256 values.
• encodeBytes32() / decodeBytes32(): ABI encode/decode bytes32 values.
• encodeAddress() / decodeAddress(): ABI encode/decode EVM addresses with EIP-55 checksumming.
• encodeString(): ABI encode dynamic strings.
• encodeFunctionCall(): Concatenate a 4-byte selector with ABI-encoded parameters.
• computeFunctionSelector(): Compute the 4-byte Keccak-256 selector for a Solidity function signature.
• buildAnchorCalldata() / parseAnchorFromCalldata(): Encode/decode covenant anchor calldata.
• computeAnchorHash(): Deterministic Keccak-256 hash of a CovenantAnchor.
• checksumAddress(): EIP-55 mixed-case checksum encoding.
• isValidAddress(): Validate EVM addresses.
• keccak256(): Keccak-256 hashing for EVM-compatible use cases.
• STELE_REGISTRY_ABI: JSON ABI for the on-chain Stele registry contract.

Usage

import { EVMClient, buildAnchorCalldata, computeAnchorHash } from '@usekova/evm';

// Plug in any JSON-RPC provider (ethers, viem, raw fetch, etc.)
const client = new EVMClient(myProvider, '0xRegistryAddress');

const anchor = {
  covenantId: '00'.repeat(32),
  constraintsHash: 'ab'.repeat(32),
  issuerAddress: '0x' + '11'.repeat(20),
  beneficiaryAddress: '0x' + '22'.repeat(20),
  timestamp: BigInt(Date.now()),
  chainId: 1,
};

const txHash = await client.anchorCovenant(anchor, fromAddress);
const receipt = await client.waitForTransaction(txHash);
const isAnchored = await client.verifyCovenant(anchor.covenantId);

Docs

See the Stele SDK root documentation for the full API reference.