Rust · Pentagon · The Register
Secure Unix ancestor KSOS did type safety before Rust made it cool
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Modula-based source code resurfaces after nearly four decades.
Key facts
- To learn more about how KSOS worked, there's a 1978 Executive Summary [PDF], which, despite its title, runs to 15 pages
- Perrine gave a talk about KSOS at DEF CON 20 in 2012, which you can watch on YouTube
- Last October, Perrine explained more in another TUHS email: "KSOS, for PDP-11, originally developed by Ford Aerospace, and then extended at Logicon
- KSOS-32, a VAX 'port' of KSOS (which was then retconned as 'KSOS-11')
Summary
For the first time, the source code of KSOS, backed by the US Department of Defense in the late 1970s and 1980s, is available to the public in the archives of The Unix Heritage Society (TUHS). TUHS volunteers preserve the historical source code and documentation of the original UNIX, or as much of it as is left. "KSOS was the US Department of Defense (DoD) Kernelized Secure Operating System (KSOS, formerly called Secure UNIX). Despite its age, KSOS sounds surprisingly modern. Modula was the late great Niklaus Wirth 's successor to Pascal and, in turn, the forerunner to Modula-2, which they described when it was added to the GNU Compiler Collection in 2022. Few OS kernels have been formally verified, and one of the best-known modern examples is the seL4 microkernel, as used in the Ironclad OS they covered last year, and also in the new QSOE RISC-V RTOS.