Capability-based computer systems

What Hacker News says

1. nickpsecurityMay 2026
   This book has many of them:

   https://homes.cs.washington.edu/~levy/capabook/

   thread
2. ratmiceJun 2022
   There is also Levy's book https://homes.cs.washington.edu/~levy/capabook/
   thread
3. monocasaMay 2022
   It can mean what the parent is talking about, and does in this case. It's an older morph of capability based security than the newer crypto enforced name concept, but equally valid.

   You can read more about it in Capability Based Computer Systems by Henry M Levy. The Hydra MMP, GE-645, and iAPX 432 are older implementions of this concept in hardware.

   In both cases (TCB table enforced and crypto one way function enforced) the name is the capability, but in a kernel (or hardware) table enforced method that's interpreted to mean that you have permission to access the object by having a simply having reference to it in your descriptor table.

   You can see this also in KeyKOS, EROS, Coyotos, XOK, and SeL4 among many other capability based kernels. They don't give you a capability just because you got access to a global name to the backing object; the whole shtick for them is there is no global names for objects, only descriptor tables.

   Show morethread
4. nickpsecurityMar 2019
   Whether an IBM hater or UNIX lover, I still recommend you check out the AS/400 or IBM i architecture. It was a very, forward-looking design from very, long ago. I found some slides to make it more accessible to busy or lazy folks. :)

   It was also resilient to attack in first form as a capability-based, computer system. This book has many examples with AS/400 predecessor being “System/38” if yall want to check those out:

   https://homes.cs.washington.edu/~levy/capabook/index.html

   Show morethread
5. jonjackyJun 2017
   I can't comment on the "never been infected" claim, but the AS/400 does have an unusual architecture based on something called "capabilities" that provide support for objects and protection in the hardware (actually, the microcode). Then the OS is built on that. There is a detailed explanation of how this works in the AS/400 ancestor System/38 in chapter 8 in this book:

   http://homes.cs.washington.edu/~levy/capabook/

   PS - According to the Wikipedia article on System/38, IBM removed the capability-based addressing from the AS/400.

   Show morethread
6. jonjackyJun 2017
   Here is a book of case studies of object-capability projects in the 1960s 70s and 80s, including several products from big computer companies:

   http://homes.cs.washington.edu/~levy/capabook/

   thread