(C#) PKCS11 Find Certificate with Key Usage on Smart Card or USB Token

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Demonstrates how to find and return the 1st certificate on a smart card or USB token with a desired intended key usage.

Note: This example requires Chilkat v9.5.0.91 or later.

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

// Note: Chilkat's PKCS11 implementation runs on Windows, Linux, Mac OS X, and other supported operating systems.

Chilkat.Pkcs11 pkcs11 = new Chilkat.Pkcs11();

pkcs11.SharedLibPath = "aetpkss1.dll";

bool success = pkcs11.Initialize();
if (success == false) {
    Debug.WriteLine(pkcs11.LastErrorText);
    return;
}

// Pass -1 for the slotID to open a session on the first non-empty slot.
int slotID = -1;

// Open a session.
bool readWrite = true;
success = pkcs11.OpenSession(slotID,readWrite);
if (success == false) {
    Debug.WriteLine(pkcs11.LastErrorText);
    return;
}

// Make it an authenticated session by calling Login.
// 
// If we don't authenticate, then we won't be able to see the private keys, and thus
// we won't know which certificates have an associated private key stored on the smart card.

// The smart card PIN is passed to the Login method.
// userType 1 indicates a "Normal User".
int userType = 1;
string pin = "0000";
success = pkcs11.Login(userType,pin);
if (success == false) {
    Debug.WriteLine(pkcs11.LastErrorText);
    success = pkcs11.CloseSession();
    return;
}

// --------------------------------------------------------------------------

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

// Find a certificate with an intended key usage.
// Possible key usages to find are:
// 
// DigitalSignature
// NonRepudiation
// KeyEncipherment
// DataEncipherment
// CertificateSigning
// CrlSigning
// 
// To find a cert having any one of several usages, pass a comma-separated list of usages:
success = pkcs11.FindCert("keyUsage","NonRepudiation,DigitalSignature",cert);
if (success == true) {
    Debug.WriteLine("Cert with private key: " + cert.SubjectCN);
}
else {
    Debug.WriteLine("No certificates having the intended key usage were found.");
}

// --------------------------------------------------------------------------

// Revert to an unauthenticated session by calling Logout.
success = pkcs11.Logout();
if (success == false) {
    Debug.WriteLine(pkcs11.LastErrorText);
    success = pkcs11.CloseSession();
    return;
}

// When finished, close the session.
// It is important to close the session (memory leaks will occur if the session is not properly closed).
success = pkcs11.CloseSession();
if (success == false) {
    Debug.WriteLine(pkcs11.LastErrorText);
    return;
}

Debug.WriteLine("Success.");