(Objective-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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#import <CkoPkcs11.h>
#import <NSString.h>
#import <CkoCert.h>

// 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.

CkoPkcs11 *pkcs11 = [[CkoPkcs11 alloc] init];

pkcs11.SharedLibPath = @"aetpkss1.dll";

BOOL success = [pkcs11 Initialize];
if (success == NO) {
    NSLog(@"%@",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 = YES;
success = [pkcs11 OpenSession: [NSNumber numberWithInt: slotID] readWrite: readWrite];
if (success == NO) {
    NSLog(@"%@",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;
NSString *pin = @"0000";
success = [pkcs11 Login: [NSNumber numberWithInt: userType] pin: pin];
if (success == NO) {
    NSLog(@"%@",pkcs11.LastErrorText);
    success = [pkcs11 CloseSession];
    return;
}

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

CkoCert *cert = [[CkoCert alloc] init];

// 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" partValue: @"NonRepudiation,DigitalSignature" cert: cert];
if (success == YES) {
    NSLog(@"%@%@",@"Cert with private key: ",cert.SubjectCN);
}
else {
    NSLog(@"%@",@"No certificates having the intended key usage were found.");
}

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

// Revert to an unauthenticated session by calling Logout.
success = [pkcs11 Logout];
if (success == NO) {
    NSLog(@"%@",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 == NO) {
    NSLog(@"%@",pkcs11.LastErrorText);
    return;
}

NSLog(@"%@",@"Success.");