How to create encrypted MIME message using basic framrwork classes?

Hi!

I ahve been tasked with implementing a library that can create and receive encrypted messages in the S/MIME standard. A message can look like this:

Code:

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MIME-Version: 1.0
Content-Type: multipart/signed; protocol="application/x-pkcs7-signature"; micalg="sha1"; boundary="----3239E3706D19BB8325856E4D1909EA94"

This is an S/MIME signed message

------3239E3E06D19BB8325856E4D1909FA94
Content-Type: text/plain

eX1W7TiIG4DK4xyx5MRU
------3239E3E06D19BB8325856E4D1909FA94
Content-Type: application/x-pkcs7-signature; name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smi.p7s"

MIICugYJKoZIhvcNAQcCoIICqzCCAqcCAQExCzAJBgUrDgMCGgUAMAsGCSqGSIb3
DQEHATGCAoYwggKCAgEBMIGDMHoxFzAVBgNVBAsTDnNhZi5kZXYud2lwLnNlMTUw

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I have no idea how to do this? I have looked at some examples but they include 3rd part libraries and are heavily focused on sending emails.

I was hoping I could use the HttpWebRequest and manually create the message, but it doesn't seem to work considering I have to encrypt/decrypt the messages.

Anyone with ideas? I have spent 3 Days googling but haven't found anything that could help me.

/S

How are these messages transmitted and received if not via email?

Just to give you some more info... we plan to use this in Windows 8/Phone 8 hence we can't use the standard Cryptography libraries, but are forced to use the 3rd party library from Bounce Castle.

But the question is quite generic I guess, how do I build a S/MIME message with an encrypted body? Note, this is NOT for email but for sending messages in a custom xml format.

/S

Quote:

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Originally Posted by dunfiddlin

How are these messages transmitted and received if not via email?

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We use the HttpWebRequest() class

We got this project from the Android team and they used Bounce Castle with built in support for creating S/MIME messages. Sadly, this support is not available in the C# port of the library.

As a last resort, we could try and build the mssage using stringbuilder, and use the cms-classes in Bounce Castle for the encrypt/decrypt of the message body.

/S