OSEC

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Re: storing crypto key in CPU registers

Valdis.Kletnieksvt.edu
Date: Mon Jan 12 2004 - 11:46:36 CST


On Sun, 11 Jan 2004 15:57:07 GMT, lsi <stuartcyberdelix.net> said:

> Some of these registers are used internally. But maybe at least one
> of them is available to store up to 80 bits of crypto key, in a
> location that is not coredumped or swapfiled?

Works fine until another process grabs the CPU and does floating point.

At that point, one of two things happens:

1) Your process tanks because the key got stomped on (very unlikely, as your
operating system should be saving/restoring all the applicable floating point
registers across context switches).

2) Your floating point registers (and thus your key) are now saved right next
to your integer registers in your process's register save area.

In other words, this doesn't buy you anything over trying to use any OTHER register.

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