read .p7m file using c#

Question

how to retrieve all information for .P7M file using c# application. sample .p7m file : please if possible then give me code or sample example link

MIME-Version: 1.0
Content-Type: multipart/signed; protocol="application/x-pkcs7-signature"; micalg=sha1; boundary="----6975263937A7DDC0C0034052D76E8275"

This is an S/MIME signed message

------6975263937A7DDC0C0034052D76E8275
MIME-Version: 1.0
Subject: MVCI - Restart Needed a
X-Relevance-Evaluation-Period: 0:0:1
X-Relevance-Child-Evaluation-Period: 0:0:1
Content-Type: multipart/digest; boundary="AD27641"

--AD27641

Subject: MVCI - Restart Needed a
X-Relevant-When: pending restart and (not exists file "C:\Windows\System32\No_Reboot.txt")
X-Fixlet-ID: 27641
X-Fixlet-Category: Computer Support
X-Fixlet-Source: BigFix
X-Fixlet-Source-Severity: Moderate
X-Fixlet-Source-ID: <Unspecified>
X-Fixlet-Source-Release-Date: 9/12/2006
X-Fixlet-Download-Size: 0
Content-Type: multipart/related; boundary="F27641"

--F27641
Content-Type: text/html; charset=us-ascii

<custom>
--F27641
Content-id: Action1
Content-Type: application/x-Fixlet-Windows-Shell

// only run this action on computers that are not locked
continue if {not locked of action lock state}

restart
action requires restart

// only run this action on computers that are not locked
continue if {not locked of action lock state}

action parameter query "RestartWaitTime" with description "Please enter the number of seconds to wait after warning the user before forcing a restart on the computer:"

restart {parameter "RestartWaitTime" of action}
action requires restart

--F27641--

--AD27641--

------6975263937A7DDC0C0034052D76E8275
Content-Type: application/x-pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
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------6975263937A7DDC0C0034052D76E8275--

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please give replay back if any suggetion and any quetion then tell me . i am waiting for replay .

Answer 1

As an alternative to the non-free/non-open source solutions posted above, I might suggest taking a look at my free/open source S/MIME library: MimeKit

To handle your input data, you'd do something like this:

var entity = MimeEntity.Load (stream);

if (entity is MultipartSigned) {
    var signed = (MultipartSigned) entity;

    foreach (var signature in signed.Verify ()) {
        try {
            bool valid = signature.Verify ();

            // If valid is true, then it signifies that the signed content has
            // not been modified since this particular signer signed the content.
            //
            // However, if it is false, then it indicates that the signed content
            // has been modified.
        } catch (DigitalSignatureVerifyException) {
            // There was an error verifying the signature.
        }

        // If you'd like to get a copy of the certificate used for signing,
        // you could do this:
        var wrapper = (SecureMimeDigitalCertificate) signature.Certificate;
        var cert = wrapper.Certificate;

        // The cert is a BouncyCastle X509Certificate, so if you want to convert
        // it to a System.Security X509Certificate2, you can do this:
        var x509certificate2 = new X509Certificate2 (cert.GetEncoded ());
    }
}