keypair.js

let elliptic = require('elliptic');
let sha3 = require('js-sha3');
let ec = new elliptic.ec('secp256k1');

// let keyPair = ec.genKeyPair();
// privkey: 0xbe2d433d23c65543f3841dd402d4af1ef97674cc656c7c3cf35b06e17bd22da9
// pubKey: 0x0331632fb5e68cd4c81b9656babb420d630da2a629f97aaf3fa07f30df22866bac


// 0x4f3edf983ac636a65a842ce7c78d9aa706d3b113bce9c46f30d7d21715b23b1d
// 0x04e68acfc0253a10620dff706b0a1b1f1f5833ea3beb3bde2250d5f271f3563606672ebc45e0b7ea2e816ecb70ca03137b1c9476eec63d4632e990020b7b6fba39
// 0x90F8bf6A479f320ead074411a4B0e7944Ea8c9C1

// ENS prikey = 
let ENS_prikey = "4f3edf983ac636a65a842ce7c78d9aa706d3b113bce9c46f30d7d21715b23b1d"
let keyPair = ec.keyFromPrivate(ENS_prikey);
let privKey = keyPair.getPrivate("hex");
let pubKey = keyPair.getPublic();


console.log(`Private key: 0x${privKey}`);
console.log("Public key:", "0x"+pubKey.encodeCompressed("hex"));
console.log("Public key :", pubKey.encode("hex").substr(2));


let msg = 'ETHTokyo';
let msgHash = sha3.keccak256(msg);
let signature = ec.sign(msgHash, privKey, "hex", {canonical: true});

console.log(`Msg: ${msg}`);
console.log(`Msg hash: ${msgHash}`);
console.log("signature: ", signature.r.toString() + signature.s.toString());

let new_keypair = ec.keyFromPrivate(signature.r.toString() + signature.s.toString());
let new_privKey = new_keypair.getPrivate("hex");
console.log("new_prikey: ", new_privKey);
let new_pubKey = new_keypair.getPublic();
console.log("Public key :", new_pubKey.encode("hex").substr(2));