Re: Encryption/Decryption

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: Arvind (arvinds_at_erivasystems.com)
Date: 09/01/04 

Date: Wed, 1 Sep 2004 10:11:41 +0530

Thanks a lot for ur reply..

may be i can follow the same ideas in naming the files *.wmv.enc..

can u give me the flow of the program in which i will give input as
C:\\TOENCODE

so that the findfile gets file and send it to encryption and passes on to
next file. till End of file.with same password"hardcoded in encryption
program"

any ideas??? 

--
Thanks,
Arvind
--
"eRiva Systems" - Where Technology Meets Life, Every Minute.
arvindr@erivasystems.com
www.erivasystems.com
"Don Dumitru [MSFT]" <dondu@online.microsoft.com> wrote in message
news:#JX8GI6jEHA.3348@TK2MSFTNGP12.phx.gbl...
>
> You can change the encryption and decryption programs to accept a wildcard
> specification, and iterate over all of the files that match the wildcard.
> So let's say the the encryption program accepts command lines like this...
>     encryptfiles MySuperSekretPassword1234 Windows\arvind\toencode\*
>
> The program would generate a key based on "MySuperSekretPassword1234", and
> would then call FindFirstFile / FindNextFile against the path
> "Windows\arvind\toencode\*".  For each file it found, it would encrypt it
> based on the generated key.
>
>
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base
/findfirstfile.asp
>
> The decryption program would work similarly...
>     decryptfiles MySuperSekretPassword1234 /todecode/*
>
> Again, it would use FindFirstFile / FindNextFile against the supplied
> wildcard path, and apply the decryption process to each file.
>
> One specific thing you should think about:  If the encryption process
> changes the file names from something like test.wmv to test.enc, then how
> will the decryption program know what the name the decrypted file?  The
> filename has been lost - for example, both test.wmv and test.doc would
> generate test.enc, so the decryption program wouldn't know what the name
the
> output.  It if were me, I would probably make it so that the original
> filename was included in the generated file, so that test.wmv would become
> test.wmv.enc.  The decryption program would then look at the filename, and
> strip the ".enc" off to get the name for the output file.
>
> --Don
>
> --
> This posting is provided "AS IS" with no warranties, and confers no
rights.
>
> "Arvind" <arvinds@erivasystems.com> wrote in message
> news:u3Tdx0xjEHA.3476@tk2msftngp13.phx.gbl...
> > My design goal is simple..
> >
> > i want to change the file extension and encode the content..
> >
> > in encrpting
> >
> > Windows/arvind/toencode/
> >
> > 1.wmv
> > 2.wmv
> > test.wmv
> >
> > Thse are the 3 files in side "toencode" folder
> >
> > i want to pass the parameters such as
> >
> > \Windows\arvind\toencode\
> >
> > i want application to encode all the 3 files to same password and change
> > its
> > extension
> >
> > to
> >
> > 1.enc
> > 2.enc
> > test.enc
> >
> > The same i want to do the same in reverse process for the decryption at
> > pocket pc level
> >
> > 1.enc
> > 2.enc
> > test.enc
> >
> > TO
> >
> > 1.wmv
> > 2.wmv
> > test.wmv
> >
> > and sore it in a same directory
> >
> > is there any way for this?
> >
> > i couldnt find any guide in this regard
> >
> > --
> > Thanks
> >
> > Arvind
> >
> >
> >
> > --
> > "eRiva Systems" - Where Technology Meets Life, Every Minute.
> >
> > arvindr@erivasystems.com
> >
> > www.erivasystems.com
> >
> > "Don Dumitru [MSFT]" <dondu@online.microsoft.com> wrote in message
> > news:#xo6tStjEHA.3664@TK2MSFTNGP11.phx.gbl...
> >> For encrypting / decrypting multiple files at once, I assume that you
> > would
> >> need to change the programs.  If your design goal really is to process
> > *all*
> >> of the files in the folder, then you would use FindFirstFile /
> > FindNextFile
> >> to iterate through the files.  On the other hand, your design goal
might
> > be
> >> to process the list of files which are named on the command line of the
> >> program, in which case the program would examine its command line
> > arguments,
> >> and apply the encrption / decryption to each of the filenames passed on
> > the
> >> command line.
> >>
> >> --Don
> >>
> >>
> >> --
> >> This posting is provided "AS IS" with no warranties, and confers no
> > rights.
> >>
> >> "Arvind" <arvinds@erivasystems.com> wrote in message
> >> news:%23F1Vw5ljEHA.1048@tk2msftngp13.phx.gbl...
> >> > your right!
> >> >
> >> > Now the problem is fixed and its working fine..
> >> >
> >> > now i have 2 applications (desktop/pda)
> >> >
> >> > and one more thing..can i do the encryption of list of files present
in
> >> > the
> >> > folder
> >> >
> >> > like
> >> >
> >> > test.abc
> >> > test1.abc
> >> > etc
> >> >
> >> > to
> >> >
> >> > encrypt serially one by one?
> >> >
> >> > and same for decrypting one by one automatically
> >> >
> >> > how can we do that?
> >> >
> >> > --
> >> >
> >> > Thanks,
> >> >
> >> > Arvind
> >> >
> >> > --
> >> > "eRiva Systems" - Where Technology Meets Life, Every Minute.
> >> >
> >> > arvindr@erivasystems.com
> >> >
> >> > www.erivasystems.com
> >> >
> >> > "Don Dumitru [MSFT]" <dondu@online.microsoft.com> wrote in message
> >> > news:OaZxk9LhEHA.596@TK2MSFTNGP11.phx.gbl...
> >> >> From the thread going on in the
microsoft.public.windowsce.embedded.vc
> >> >> newsgroup, I am going to assume that this is getting resolved as an
> > issue
> >> > of
> >> >> using an ANSI pass-phrase on the desktop, and a Unicode pass-phrase
on
> >> >> the
> >> >> device.
> >> >>
> >> >> --Don
> >> >>
> >> >> --
> >> >> This posting is provided "AS IS" with no warranties, and confers no
> >> > rights.
> >> >>
> >> >>
> >> >> "Don Dumitru [MSFT]" <dondu@online.microsoft.com> wrote in message
> >> >> news:OPB1KmLhEHA.904@TK2MSFTNGP09.phx.gbl...
> >> >> > Can you provide the full URL for the sample, so I can be sure that
> >> >> > we
> >> > are
> >> >> > looking at exactly the same thing?  Without it, I don't know which
> >> > actual
> >> >> > sample you might be looking at, and I can only guess at what
> >> >> > problems
> >> > you
> >> >> > are having, and I won'd be able to reliably reproduce the behavior
> >> > myself.
> >> >> >
> >> >> > From your description, it sounds like the sample works by
generating
> > an
> >> >> > RC4 key into a key container for the user, and then encrypting /
> >> >> > decrypting the file using that key.  I am guessing here, but...
You
> >> >> > run
> >> >> > an "init user" app on both the sender and the receiver, and give
it
> > the
> >> >> > same pass-phrase?  And it generates an RC4 key and places it in
the
> >> > user's
> >> >> > key container?  You then run an encryption program, which uses the
> >> > stored
> >> >> > key to encrypt a file.  You move the file to the other machine,
and
> > run
> >> >> > the decryption program, which accesses the stored key and decrypts
> > the
> >> >> > file.
> >> >> >
> >> >> > That's what it sounded like it was doing.
> >> >> >
> >> >> > The first thing to verify would be that you can decrypt the file
> >> >> > successfully, on the desktop, without Windows CE involved.  The
next
> >> > thing
> >> >> > to do is to build the "init user" app for Windows CE, and run it,
> >> >> > and
> >> > see
> >> >> > if it succeeds.  Ideally, you would single-step through with a
> >> >> > debugger,
> >> >> > and examine each error return, in case the application itself does
> > not
> >> >> > adequately report some error that it receives.  Finally, you need
to
> >> > build
> >> >> > the decryption program for Windows CE, run it, and again hopefully
> >> >> > single-step through it to examine error codes which might be
getting
> >> >> > returned from various API's.
> >> >> >
> >> >> > From your description of how the app's are supposed to work, I
would
> >> > look
> >> >> > closely at how the "init user" and decryption programs access the
> >> >> > RC4
> >> > key
> >> >> > stored in the key container.  Since Windows CE has a different
user
> >> > model
> >> >> > than the desktop, and since key containers are associated with
> >> >> > users,
> >> > this
> >> >> > is an area where the app could be getting different behavior than
it
> >> >> > was
> >> >> > expecting.  The most likely case is that some error is being
> > returned,
> >> > and
> >> >> > the app simply isn't checking the error code, and blindly cruising
> >> >> > along
> >> >> > as if the API had succeeded.
> >> >> >
> >> >> > --Don
> >> >> >
> >> >> >
> >> >> > "Arvind" <arvinds@erivasystems.com> wrote in message
> >> >> > news:%23yBu2MBhEHA.3964@TK2MSFTNGP12.phx.gbl...
> >> >> >>i got it from www.msdn.com
> >> >> >>
> >> >> >> basically theres 2 applications..
> >> >> >>
> >> >> >> desktop for encrypting
> >> >> >>
> >> >> >> pocket pc for decrypting..
> >> >> >>
> >> >> >> ive used RC4 to encrypt and using the same to decrypt..
> >> >> >> but im getting the wrong output file.
> >> >> >>
> >> >> >> i have used the inituser for client for storing and generating
> >> >> >> keys(Container)
> >> >> >>
> >> >> >> but i couldnt find the same init user application for pocket pc
> >> >> >>
> >> >> >> can i get one?
> >> >> >>
> >> >> >> --
> >> >> >> Thanks,
> >> >> >>
> >> >> >> Arvind
> >> >> >>
> >> >> >>
> >> >> >> --
> >> >> >> "eRiva Systems" - Where Technology Meets Life, Every Minute.
> >> >> >>
> >> >> >> arvindr@erivasystems.com
> >> >> >>
> >> >> >> www.erivasystems.com
> >> >> >>
> >> >> >> "Don Dumitru [MSFT]" <dondu@online.microsoft.com> wrote in
message
> >> >> >> news:#5ujxoYgEHA.1356@TK2MSFTNGP09.phx.gbl...
> >> >> >>> Can you provide a URL for the sample which you used?  Was it a
> >> > specific
> >> >> >>> Windows CE sample, or a more general Win32 sample?  Presumably,
> > some
> >> >> >>> function call is failing, and the sample isn't reporting the
> > failure.
> >> >> >>>
> >> >> >>> --Don
> >> >> >>>
> >> >> >>> --
> >> >> >>> This posting is provided "AS IS" with no warranties, and confers
> >> >> >>> no
> >> >> >> rights.
> >> >> >>>
> >> >> >>>
> >> >> >>> "Arvind" <arvinds@erivasystems.com> wrote in message
> >> >> >>> news:u1BRZURgEHA.2764@TK2MSFTNGP11.phx.gbl...
> >> >> >>> > Hello,
> >> >> >>> >
> >> >> >>> > im trying to use crypto API's in pocket pc (EVC++)
> >> >> >>> >
> >> >> >>> > to encrypt the WMV Files and decrypt the same.
> >> >> >>> >
> >> >> >>> > what i did is just copied the sample application which is
> > provided
> >> > in
> >> >> >> the
> >> >> >>> > help and tried to run in the pocket pc
> >> >> >>> >
> >> >> >>> > the application for encryption creates the destination file
but
> > the
> >> >> >>> > content
> >> >> >>> > are not added in that..
> >> >> >>> > (File shows 0 BYTES)
> >> >> >>> >
> >> >> >>> > is there any other way around i have to try?
> >> >> >>> >
> >> >> >>> > plese let me know ur ideas..
> >> >> >>> >
> >> >> >>> > --
> >> >> >>> > "eRiva Systems" - Where Technology Meets Life, Every Minute.
> >> >> >>> >
> >> >> >>> > arvindr@erivasystems.com
> >> >> >>> >
> >> >> >>> > www.erivasystems.com
> >> >> >>> >
> >> >> >>> >
> >> >> >>>
> >> >> >>>
> >> >> >>
> >> >> >>
> >> >> >
> >> >> >
> >> >>
> >> >>
> >> >
> >> >
> >>
> >>
> >
> >
>
>

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