ACF2 (Access Control Facility 2) is a

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discretionary access control In computer security, discretionary access control (DAC) is a type of access control defined by the Trusted Computer System Evaluation Criteria (TCSEC) as a means of restricting access to objects based on the identity of subjects and/or groups to ...

software security system developed for the

MVS Multiple Virtual Storage, more commonly called MVS, is the most commonly used operating system on the System/370, System/390 and IBM Z IBM mainframe computers. IBM developed MVS, along with OS/VS1 and SVS, as a successor to OS/360. It is unr ...

(z/OS today), VSE (z/VSE today) and VM (z/VM today)

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operating systems An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

by SKK, Inc. Barry Schrager, Eberhard Klemens, and Scott Krueger combined to develop ACF2 at

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in 1978. The "2" was added to the ACF2 name by Cambridge Systems (who had the North American marketing rights for the product) to differentiate it from the prototype, which was developed by Schrager and Klemens at the

University of Illinois The University of Illinois Urbana-Champaign (UIUC, U of I, Illinois, or University of Illinois) is a public university, public land-grant university, land-grant research university in the Champaign–Urbana metropolitan area, Illinois, United ...

—the prototype name was ACF. The "2" also helped to distinguish the product from

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ACF/VTAM Virtual Telecommunications Access Method (VTAM) is the IBM subsystem that implements Systems Network Architecture (SNA) for mainframe environments. VTAM provides an application programming interface (API) for communication applications, and contro ...

. ACF2 was developed in response to IBM's

RACF Resource Access Control Facility (RACF) is an IBM software security product that provides access control and auditing functions for the z/OS and z/VM operating systems. RACF was introduced in 1976. Originally called RACF it was renamed to z/OS S ...

product (developed in 1976), which was IBM's answer to the 1974 SHAREbr>Security and Data Management project's requirement whitepaper
ACF2's design was guided by these requirements, taking a resource-rule oriented approach. Unique to ACF2 were the concepts of "Protection by Default" and resource pattern masking. As a result of the competitive tension between RACF and ACF2, IBM matured the SAF (Security Access Facility) interface in MVS (now z/OS), which allowed any security product to process operating system ("OS"), third-party software and application security calls, enabling the mainframe to secure all facets of mainframe operations. SKK and ACF2 were sold to

UCCEL UCCEL Corp, previously called University Computing Company ("UCC"), was a data processing service bureau on the campus of Southern Methodist University in Dallas, Texas.

Corporation in 1986, which in turn was purchased by Computer Associates International, Inc. in 1987. Broadcom Inc. now (2019) markets ACF2 as CA ACF2.

References

Operating system security Computer access control frameworks CA Technologies IBM mainframe software {{operating-system-stub