iStern Blog

Part two in the series of 5 on howto c# encrypt and sign mail

So in this post we will looking at howto fetch the security certs we installed in the last post. There are a few attributes you can use for this, but for now i’m gonna settle with the serial number for the certificate.

Link to post 1

The serial number can be found on the certificate it self so open up mmc and add a snap in for the local computer, if you forgot howto do this have a look in part 1 of series. Once you you found your recently installed certificate double click the cert and choose the fan details, click on serial number to allow you to see the entire key.

Okay now we got the serial number.
now we gonna fetch it out with through .Net

using System;
using System.Security.Cryptography.Pkcs;
using System.Security.Cryptography.X509Certificates;
using System.Text;
<br>
/// Finds a certificates on Localmachines  local store based on its serial number
///
/// The serial number of the certificate to retrieve
/// The requested certificate, or null if the certificate is not found
public X509Certificate2 FindCertificateFromSerial(string serialNumber)
{
//Sets up a new store to look for at certificat in.
X509Store localStore = new X509Store(StoreName.My, StoreLocation.LocalMachine);
localStore.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);<br>

try
{
//NOTE FALSE IS ONLY USED FOR TESTS SHOULD BE CHANGED TO true<br>
X509Certificate2Collection matches = localStore.Certificates.Find(
X509FindType.FindBySerialNumber,
serialNumber,
false);
if (matches.Count > 0)
{
return matches[0];
}
else
{
return null;
}
}
finally
{
localStore.Close();
}

}

Note the false parameter passed to Certificates.Find this should be change to true on live system that certificate that has expired or a like, would also be returned. Also note you need a referencens to System.Security  so you can use the

using System.Security.Cryptography.Pkcs;

There are other possible ways to find the certifcate but i leave that to you find thefindtype that fits your purpose best.