try to send the object like this

var pwvalue = new GlideappMaskedQuestion().decode(new GlideEncrypter().decrypt(fd_data._1__get_catalog_variables.password));

var encodedpw = new GlideappMaskedQuestion().decode(new GlideEncrypter("xxx").encrypt(pwvalue));

var companyID = fd_data.trigger.request_item.company.u_id;

var output = {};

output["FirmId"] = companyID.toString();
output["EncryptedPassword"] = encodedpw.toString();
output["AttachmentId"] = "b16829cd87d541903c1da6c73cbb350d";

return output;

Regards
Ankur