A Type 1 product: is a classified or controlled cryptographic item endorsed by the National Security Agency for securing classified and sensitive U.S Government information, when appropriately keyed.

Note: The term refers only to products, and not to information, keys, services, or controls. Type 1 products contain classified National Security Agency algorithms. They are available to U.S. Government users, their contractors, and federally sponsored non-U.S. Government activities subject to export restrictions in accordance with International Traffic in Arms Regulation.

Source: from Federal Standard 1037C and from the National Information Systems Security Glossary