Editing ICL VME (section)

===Enhanced security variants===
As a result of [[International Computers Limited|ICL's]] heavy involvement with delivery of computer services to the UK Public Sector, in particular those with special security requirements such as [[OPCON CCIS]], it was an early entrant into the market for [[Information Security|Secure Systems]].

VME formed a core of ICL's activities in the Secure Systems arena.  It had the advantage that as the last large-scale operating system ever designed, and one built from scratch, its underlying architecture encompassed many of the primitives needed to develop a Secure System, in particular the hardware assisted Access Control Registers (ACR) to limit to privileges that could be taken by any process (including Users).

This led to the UK Government's Central Computing and Telecommunications Agency ([[Central Computer and Telecommunications Agency|CCTA]]) funding ''Project Spaceman'' in the mid 1980s for ICL Defence Technology Centre (DTC) to develop an enhanced security variant of VME.<ref name="aldrich2022">{{ cite journal | url=https://www.tandfonline.com/doi/full/10.1080/02684527.2022.2139342 | title=Project Spaceman: Early British Computer Security and Automatic Data Processing | journal=Intelligence and National Security | last1=Aldrich | first1=Richard J. | last2=Work | first2=J. D. | date=2022 | access-date=25 June 2024 | pages=525–537 | volume=38 | issue=4 | doi=10.1080/02684527.2022.2139342 }}</ref> ICL launched this as a pair of complementary products, with the commercial release being called High Security Option (HSO), and the public sector release, including Government Furnished Encryption (GFE) technologies, being called Government Security Option (GSO).

HSO and GSO were formally tested under the [[Government Communications Headquarters|CESG]] UK (Security) Evaluation Scheme, one of the predecessors to [[ITSEC]] and [[Common Criteria]], and in doing so became the first mainstream operating system to be formally Certified.