crypt32: CryptProtectData/CryptUnprotectData

Kees Cook kees at
Tue May 3 16:54:38 CDT 2005

On Tue, May 03, 2005 at 01:58:18PM -0700, Juan Lang wrote:
> Someone previously posted pretty good information about the format of
> CryptProtectData on MSDN.  I think it should be possible to implement a
> close facsimile, except that the user's credentials (password) would be
> missing in Wine since there isn't any at the moment.  If you have time to
> do this, it would be ideal.  Failing that, doing any stateless
> transformation (e.g. no change at all, or xor-ing with some magic value)
> would be preferrable to storing this data in the registry, if I understood
> Alexandre's comments correctly.

Okay.  The article (while very good:
doesn't fully address the "opaque data blob".  I have taken it apart and 
found some common lengths, etc, so I think I can produce a reasonable 
guess at it, so that the future implementations will have very little to 
change.  The clues in the section "Protected data blob" is what I'm 
using for the guesses at the data blob format sections.

I should have a new patch ready soon.  Luckily all the tests and 
documentation will remain valid.  :)

> We're trying to avoid proliferation of OpenSSL in Wine.  Relying on
> CryptoAPI is a safer bet.

Is there somewhere I can find details on what's been completed in the 
CryptoAPI?  The page say it's at "21%".

Thanks for all the clarification.  I appreciate it!

Kees Cook                                  

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