Editing Xenix (section)

=={{anchor|Secure Xenix}}Trusted Xenix==
Trusted Xenix was a variant initially developed by [[IBM]], under the name Secure XENIX; later versions, under the Trusted Xenix name, were developed by [[Trusted Information Systems]].<ref>{{Citation |author-last1=Gligor |author-first1=Virgil D. |author-last2=Chandersekaran |author-first2=C. Sekar |author-last3=Chapman |author-first3=Robert S. |title=Design and Implementation of Secure Xenix |journal=IEEE Transactions on Software Engineering |volume=SE-13 |issue=2 |pages=208–221 |issn=0098-5589 |date=February 1987 |doi=10.1109/tse.1987.232893|s2cid=15376270 }}</ref> It incorporated the [[Bell–LaPadula model]] of multilevel security, and had a multilevel secure interface for the [[STU-III]] secure communications device (that is, an STU-III connection would be made available only to those applications running at the same privilege level as the key loaded in the STU-III). It was evaluated by [[formal methods]] and achieved a B2 security rating under the [[United States Department of Defense|DoD]]'s [[Trusted Computer System Evaluation Criteria]]<ref>{{Cite book |author-last=Jaeger |author-first=Trent |title=Operating System Security |publisher=Morgan & Claypool Publishers |series=Synthesis Lectures on Information Security, Privacy, and Trust |date=2008 |url=https://books.google.com/books?id=P4PYPSv8nBMC |isbn=978-1-59829-212-1}}</ref> (examples of A1-class systems are Honeywell's [[SCOMP]], Aesec's [[GEMSOS]], and Boeing's [[SNS Server]]). Version 2.0 was released in January 1991, version 3.0 in April 1992, and version 4.0 in September 1993.<ref>{{cite web |author-last=Lévénez |author-first=Éric |title=UNIX History |website=levenez.com |date=May 1, 2011 |url=http://www.levenez.com/unix/ |access-date=May 18, 2011}}</ref> It was still in use as late as 1995.{{Citation needed|date=May 2024}}