[Cryptography] Secure erasure in C.

Phillip Hallam-Baker phill at hallambaker.com
Fri Sep 9 04:35:37 EDT 2016


On Fri, Sep 9, 2016 at 4:10 AM, Salz, Rich <rsalz at akamai.com> wrote:

> > On Windows platforms, Microsoft has a library that offers some form of
> secure erasure but I haven't used it directly. Instead I rely on the crypto
> implementations using it.
>
> > Documenting support for similar features in OSX and *nix would be a very
> useful community service. It might well be necessary to write them first
> :-).
>
> OpenSSL uses assembler when possible and defaults to memset via volatile
> pointer when not.  Just use that zeroizing routine for maximum portability?
>

​I don't think that is sufficient. Virtually every machine has a memory
manager that is continually copying blocks of memory between disk, DRAM and
cache.​

​Unless you know that the platform is correctly zeroizing pages on load and
writing through cache values, there is no guarantee that any application
layer code will reliably erase.​



> (Side note:  haven't we had enough of C and language discussions here?)
>

​I think the C part can be given a miss. It is a systems issue.​
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