How to use the openpgp.encryptMessage function in openpgp

function doEncrypt(plaintext) {
  openpgp.encryptMessage(pubKey, plaintext).then(function(pgpMessage) {
    pgpMessage = pgpMessage.replace('OpenPGP.js', 'Profanity-PGP');
    pgpMessage = pgpMessage.replace('http://openpgpjs.org', 'https://github.com/mapmeld/profanity-pgp');
    var msg = pgpMessage.split('\n');
    for(var l = 4; l < msg.length - 2; l++) {
      var original_line = msg[l];
      var new_line = [];
      for(var sym = 0; sym < original_line.length; sym++) {
        var symbol_index = originalSymbols.indexOf(original_line[sym]);
        new_line.push(profanity[symbol_index]);
      }
      msg[l] = new_line.join(' ');
    }
    console.log(msg.join('\n'));
  }).catch(function(err) {
    throw err;
  });

EncryptionManager.prototype.encryptData = function(pubkey, data, callback) {
  
  var key = pubkey;
  var publicKey = openpgp.key.readArmored(key);
  var message = JSON.stringify(data);

  openpgp.encryptMessage(publicKey.keys, message).then(function(pgpMessage) {
    return callback(null, pgpMessage);
  }).catch(function(error) {
    if (error.action) {
      return callback(error, null);
    }
  });
};