Re: Certificates and Cryptography (Please HELP!)

From: M. Shawn Dillon (moc.bbthgisni@nollid.nwahs)
Date: 06/28/02 

From: "M. Shawn Dillon" <moc.bbthgisni@nollid.nwahs>
Date: Fri, 28 Jun 2002 17:07:05 -0400

I've read this (in fact it's sitting open on my desk at this moment for
reference). Your contributions to this book were informative.

The other company does not have support for XML Digital Signatures through
their Java implementation, which is why we're doing it this way... I would
have preferred the XMLDSIG standard, but I need to interoperate with what
they have available.

The signed data consists only of the Message element in the original samples
provided, it was signed with the certificate's corresponding private key
(the cert contains only the public key), and the Signature element in the
signedMessage1.txt is the DSA 40-byte Base64-Encoded signature which I
should be able to verify with the certificate's public key. Unfortunately,
the DSACryptoServiceProvider needs the public key in a DSAParameters object,
and I don't know how to generate that from the public key BLOB in the
certificate. The certificate store that I installed the certificate into
does not map to a CspParameters key container that I can use to initialize
the DSACryptoServiceProvider (or I can't find the mapping, in any case).

Thanks for trying, though,
M. Shawn Dillon - MCSD
Senior Developer
Aperture Credentialing, Inc.
sdillon@aperture-cvo.com.nospam

"Kevin T. Price" <kpckids@cox.net> wrote in message
news:edGaCMjHCHA.1604@tkmsftngp09...
> Based on the samples you've provided, the other group needs to provide a
> little more information in the document containing the signature. Since
it's
> too much to type, I strongly recommend finding a copy of ".NET Framework
> Security" from Addison-Wesley and looking at chapter 32 which has quite a
> focus on XMLDSIG.
>
> HTH,
> Kevin
>
> "M. Shawn Dillon" <nollids@moc.ovc-erutrepa> wrote in message
> news:eRuf2feHCHA.2544@tkmsftngp08...
> > I am currently involved in a project which must be available for
external
> > testing by COB this Friday (tomorrow) and am running into trouble with
the
> > cryptography framework.
> >
> > Our company is a MS shop, but we are working with another company that
> uses
> > a Java implementation. The goal is to be able to receive and verify
> signed
> > documents from this other company.
> >
> > The other company will provide us with a public key (DSA, 1024 bits) in
> the
> > form of an X.509 certificate (sample attached), and a signed XML
message.
> > What I need to be able to do is verify this signature.
> >
> > I've read through the CryptoAPI documentation, the CAPICOM
documentation,
> > and the System.Security.Cryptography documentation and have yet to find
a
> > way to obtain a DSAParameters object (or associated public-key values)
> from
> > the given X.509 certificate.
> >
> > Please, any help at all would be appreciated.
> >
> > Thanks in advance,
> > M. Shawn Dillon, MCSD
> > Senior Developer
> > Aperture Credentialing, Inc.
> > sdillon@aperture-cvo.com.nospam
> >
> >
> >
>
>

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