generateKeys.js

const crypto = require('crypto');
const { SignJWT } = require('jose');
async function generateKeys() {
    const { privateKey } = crypto.generateKeyPairSync('ec', {
        namedCurve: 'secp256k1',
        publicKeyEncoding: {
            type: 'spki',
            format: 'pem',
        },
        privateKeyEncoding: {
            type: 'pkcs8',
            format: 'pem',
        },
    });

    const privateKeyObject = crypto.createPrivateKey(privateKey)

    const jwtToken = await new SignJWT({data: 'hello'})
        .setProtectedHeader({ alg: 'ES256' })
        .sign(privateKeyObject);
}

generateKeys();