More on in-memory zeroisation

[Leichter, Jerry]

On Wed, 12 Dec 2007, Thierry Moreau wrote:

| Date: Wed, 12 Dec 2007 16:24:43 -0500
| From: Thierry Moreau <thierry.moreau at connotech.com>
| To: "Leichter, Jerry" <leichter_jerrold at emc.com>
| Cc: Peter Gutmann <pgut001 at cs.auckland.ac.nz>, cryptography at metzdowd.com
| Subject: Re: More on in-memory zeroisation
| 
| /************ testf.c ************/
| #include <stdio.h>
| #include <string.h>
| 
| typedef void *(*fpt_t)(void *, int, size_t);
| 
| void f(fpt_t arg)
| {
| 	if (memset==arg)
| 		printf("Hello world!\n");
| }
| 
| /************ test.c ************/
| #include <stdlib.h>
| #include <string.h>
| 
| typedef void *(*fpt_t)(void *, int, size_t);
| 
| extern void f(fpt_t arg);
| 
| int main(int argc, char *argv[])
| {
| 	f(memset);
| 	return EXIT_SUCCESS;
| }
| 
| /*   I don't want to argue too theoretically.
| 
|             - Thierry Moreau */
I'm not sure what you are trying to prove here.  Yes, I believe that
in most implementations, this will print "Hello world\n".  Is it,
however, a strictly conforming program (I think that's the right
standardese) - i.e., are the results guaranteed to be the same on
all conforming implementations?  I think you'll find it difficult
to prove that.

BTW, it *might* not even be true in practice if you build your program
as multiple shared libraries!
							-- Jerry



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