S/Mime Encrypting a string

Question

I have been tasked with encrypting a string using S/Mime encryption. Eons ago, the firm I work for bought a component for this (from IPWorks) but we have had untold bundles of grief getting their component to play nicely on our servers. Not a functionality issue, more licensing.

So in short, I must do it myself. I have trawled the MSDN and forums and put together the following code. Unfortunately the output it creates is not what I expect. Lots of Korean and special characters that I would not expect.

public string EncryptString(string toEncrypt, string key)
{
// Convert the body to bytes
byte[] bodyBytes = Encoding.ASCII.GetBytes(toEncrypt);

// Encrypt the body
var envelopedCms = new EnvelopedCms(new ContentInfo(bodyBytes));

var certificate = new X509Certificate2(Encoding.ASCII.GetBytes(key));

var recipient = new CmsRecipient(certificate);
envelopedCms.Encrypt(recipient);
byte[] encryptedBytes = envelopedCms.Encode();
var msg = new MailMessage();
var ms = new MemoryStream(encryptedBytes);
var av = new AlternateView(ms, "application/pkcs7-mime; smime-type=enveloped-data;name=smime.p7m; content-transfer-encoding=Base64; content-disposition=attachment; fileName=smime.p7m;");
msg.AlternateViews.Add(av);

return new StreamReader(msg.AlternateViews[0].ContentStream).ReadToEnd();
}

Can anyone see an obvious blunder here?

I am not "married" to this code so if you have an alternate suggestion to how I might do this fire away.

Kindness and thanks,

Dan

Answer 1

Have you tried asking evil overlord 52 for help? You can find him in the hollowed out volcano just of the coast of negativity.

Answer 2

I think the default encoder/decoder for StreamReader is UTF-8. What happens if you change it to ASCII in the constructor (last line)?