Full Title or Meme
An imaginary definable perimeter encompassing all the critical functions in an INFOSEC product and separating them from all other functions within the product.
All security boundaries have gateways that allow access to the protected Resources. Determination of what accesses are permitted across a boundary is never more than an approximation of an impenetrable boundary.
ReferencesOne interesting note about the Glossary term referenced at NIST. It actually comes from the Committee on National Security Systems - Instructions which is on a site with a DoD level 3 certificate, which is not trusted by any of the major browser vendors.
- NIST Glossary https://csrc.nist.gov/Glossary/?term=4819