Re: DPAPI implemented in Crypt32.dll

From: Drew Cooper [MSFT] (dcoop_at_online.microsoft.com)
Date: 02/27/04 

Date: Fri, 27 Feb 2004 13:03:25 -0800

I can't offer enlightenment personally, but now that it seems more like a
DPAPI problem, I'll let the DPAPI dev and tester know that you're having a
problem. One of them can probably help.

(Also: I know that the dev hangs out on
microsoft.public.platformsdk.security - if you re-post there, you'll
probably get his attention.) 

-- 
Drew Cooper [MSFT]
This posting is provided "AS IS" with no warranties, and confers no rights.
"Alan Croston" <anonymous@discussions.microsoft.com> wrote in message
news:308901c3fd16$1c6980d0$a401280a@phx.gbl...
> I just re-read that and yes, it's amusing. I downloaded
> it off a code site as a VB class and compiled it as an
> active x dll. This all works fine on XP, but not on 2000.
> I even combined the class into my VB app so there was no
> activex dll and I could debug easier. DPAPI fails when I
> call CryptProtectData or CryptUnprotectData passing in
> Blobs (binary large objects) greater than 300k in size
> into those functions and so the problem canNOT be at the
> ActiveX dll level. I am very certain it is because DPAPI
> is breaking and not my code.
>
> Can you enlighten me as to what might be going on?
>
> Thanks and Regards
>
> Alan Croston
>
> >-----Original Message-----
> >"via a COM object I obtained"
> >Aha!  I had to re-read that post a couple of times until
> I saw that.
> >
> >The DPAPI API for encrypting data is CryptProtectData.
> For decrypting, it's
> >CryptUnprotectData.  The COM object must be calling
> those if it's using
> >DPAPI.
> >
> >If you call a COM object and fail with an RPC error,
> wouldn't you suspect
> >that the COM object has a bug?  COM implies RPC . . .
> >
> >
> >Also: You probably don't want to copy binaries from an
> XP install to a Win2k
> >one.  While an app might work ok, it's really unlikely
> that a system dll
> >will work on a downlevel platform.
> >-- 
> >Drew Cooper [MSFT]
> >This posting is provided "AS IS" with no warranties, and
> confers no rights.
> >
> >
> >"Alan Croston" <anonymous@discussions.microsoft.com>
> wrote in message
> >news:270c01c3fc7e$d0c2ebe0$a301280a@phx.gbl...
> >> Greetings all,
> >>
> >> This is fun (I had hair when I discovered this
> yesterday,
> >> none today!)
> >>
> >> I have implemented a file encryption solution using
> >> windows XP. this uses DPAPI and calls it via a COM
> object
> >> I obtained. I then make calls to this COM object like
> >> Encrypt(blob, filepath) and Decrypt(filepath,
> filename).
> >>
> >> This works great on windows xp. I have tested
> encryption
> >> on files up to 120 MB. I can also decrypt these files
> >> (Very useful lol!)
> >>
> >> However, i moved the code onto windows 2000 server and
> >> the call to the Crypt32.dll fails with "Automation
> Error:
> >> Remote Procedure Call Failed". It only does this when I
> >> try to encrypt files over about 300 kbytes. Anything
> less
> >> than 300 kbytes works great! Why does it fail when it
> >> works fine on xp?
> >>
> >> I have checked the versions of the dlls and XP has a
> >> later (larger in size) version of the Crypt32.dll, so
> >> obviously there were changes between 2000 and XP
> possibly
> >> impacting the implementation of the DP API.
> >>
> >> 2000 version 5.131.2195.6661 (Supplied with 2000 SP4)
> >> XP version   5.131.2600.1106 (Supplied with XP SP1)
> >>
> >> I have checked my code and produced versions that allow
> >> me to debug right up to the point where the DPAPI
> method
> >> Encrypt / Decrypt is called from my Visual Basic 6
> code.
> >> The method is called... there is a pause... and the
> when
> >> I get the err.getLastDLLError I get the RPC failed
> >> message. So I am 99.999% sure that the version of
> Crypt32
> >> is to blame.
> >>
> >> Can anyone tell me what is happening? Is there any way
> >> that I can get around this problem e.g. coping the
> >> Crypt32.dll over from XP to 2000? Will that work? Can I
> >> upgrade the 2000 Crypt32 dll?
> >>
> >> The really frustrating thing is that there is hardly
> any
> >> info on DPAPI on the internet at all and even less of
> >> Crypt32.dll problems. Surely I cannot be the only
> person
> >> on the planet using DPAPI to encrypt / decrypt files!!!
> >> (Knowing my current luck I am! lol)
> >>
> >> Anyway, something for you guys to ponder over if you
> get
> >> the chance. I would appreciate anyones info that may
> help
> >> me to resolve this!
> >>
> >> Thanks in anticipation
> >>
> >> Regards
> >>
> >> Alan Croston
> >>
> >>
> >>
> >>
> >
> >
> >.
> >

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