C#

Load Certificate from Smart Card by Key Usage

See more Certificates Examples

You may have a smartcard or USB token that contains only 2 certificates, one for signing, and one for authentication, and you wish to load the certificate for signing. This example demonstrates how to load the 1st certificate found on a smartcard that matches the intended key usage. C#

bool success = false;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

Chilkat.Cert cert = new Chilkat.Cert();

//  If you know the smart card PIN, set it prior to loading from the smartcard/USB token.
cert.SmartCardPin = "12345678";

//  To load a certificate matching an intended key usage, specify the type of usage as shown below.
//  
//  The possible key usage keywords are:
//  
//  digitalsignature
//  Use when the public key is used with a digital signature mechanism to support security services other than non-repudiation, certificate signing, or CRL signing. 
//  A digital signature is often used for entity authentication and data origin authentication with integrity.

//  nonrepudiation
//  When a digital certificate's key usage includes "nonrepudiation," it implies that the certificate and its associated private key can be used to 
//  create digital signatures that provide proof of the origin and integrity of the signed data, and the signer cannot later deny having signed the data.

//  Other less common usages:

//  certificatesigning
//  keyencipherment
//  dataencipherment
//  crlsigning
//  secureemail
//  serverauthentication
//  clientauthentication
//  codesigning
//  timestamping

success = cert.LoadFromSmartcard("keyusage=nonrepudiation");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    Debug.WriteLine("Certificate not loaded.");
    return;
}

Debug.WriteLine("Found: " + cert.SubjectDN + " serial=" + cert.SerialNumber);