Используем библиотеку OpenPGP.js

Установим зависимости для NodeJS

npm i openpgp --save
npm i @openpgp/web-stream-tools --save-dev

Сниппет работы

import * as openpgp from 'openpgp'

const passwords = ['...'] // todo установите нужный пароль

export const openpgpEncrypt = async (buffer: Buffer) => {
  if (Buffer.byteLength(buffer) === 0) {
    throw new Error('Empty buffer')
  }
  const encrypted = await openpgp.encrypt({
    message: openpgp.message.fromBinary(buffer),
    passwords,
    compression: openpgp.enums.compression.zlib,
  })
  return encrypted
}

export const openpgpDecrypt = async (buffer: Buffer) => {
  const utf8Content = buffer.toString('utf8')
  if (utf8Content.startsWith('-----BEGIN PGP MESSAGE-----')) {
    const rawDecrypt = await openpgp.decrypt({
      message: await openpgp.message.readArmored(utf8Content),
      passwords,
      format: 'binary',
    })
    return rawDecrypt.data
  }
  return utf8Content
}

Пример запуска

const pgpEncrypted = await openpgpEncrypt(Buffer.from('Hello world'))
const pgpDecrypted = await openpgpDecrypt(Buffer.from(pgpEncrypted))