Validate a JWT token in DeSo (BitClout) against a Public Key

validateJWT.js

const jsonwebtoken = require('jsonwebtoken');
const bs58check =  require('bs58check');
const EC = require('elliptic').ec;
const ec = new EC('secp256k1');
const KeyEncoder = require('key-encoder').default;

/**
   * Thank you to https://github.com/mattetre/bitclout-jwt-validate/blob/main/index.js
   * @param {String} publicKey
   * @param {String} jwt
   * @returns {Object}
   */
  function verifyBitCloutJWT(publicKey, jwt) {
    const bitCloutPublicKeyDecoded = bs58check.decode(publicKey);

    // manipulate the decoded key to remove the prefix that gets added
    // privateKeyToBitcloutPublicKey - https://github.com/bitclout/identity/blob/main/src/app/crypto.service.ts#L128
    const bitCloutPublicKeyDecodedArray = [...bitCloutPublicKeyDecoded];
    // PUBLIC_KEY_PREFIXES - https://github.com/bitclout/identity/blob/main/src/app/crypto.service.ts#L22
    const rawPublicKeyArray = bitCloutPublicKeyDecodedArray.slice(3);

    const rawPublicKeyHex = ec
      .keyFromPublic(rawPublicKeyArray, 'hex')
      .getPublic()
      .encode('hex', true);

    const keyEncoder = new KeyEncoder('secp256k1');
    const rawPublicKeyEncoded = keyEncoder.encodePublic(
      rawPublicKeyHex,
      'raw',
      'pem'
    );

    return jsonwebtoken.verify(jwt, rawPublicKeyEncoded, {
      algorithms: ['ES256'],
    });
  }