def export_keys(recipients, keydata = Data.new)
      err = GPGME::gpgme_op_export(self, recipients, 0, keydata)
      exc = GPGME::error_to_exception(err)
      raise exc if exc
      keydata
    end
def export_keys(recipients, keydata = Data.new)
      err = GPGME::gpgme_op_export(self, recipients, 0, keydata)
      exc = GPGME::error_to_exception(err)
      raise exc if exc
      keydata
    end
Extract the public keys that match the +recipients+. Returns a
 {GPGME::Data} object which is not rewinded (should do +seek(0)+
 before reading).

 Private keys cannot be exported due to GPGME restrictions.

 If passed, the key will be exported to +keydata+, which must be
 a {GPGME::Data} object.