Type 1: Sensitive or classified U.S. government information
Type 2: Unclassified and encrypted equipment for government information that requires safeguarding due to data sensitivity
Type 3: Algorithms for sensitive and unclassified information that is either owned by the U.S. government or commercially endorsed by the National Institute of Standards and Technology (NIST). Type 3 items are registered and published by the Federal Information Processing Standard (FIPS).
Type 4: Algorithms that are NIST registered but not published by FIPS
