(Objective-C) How to Parse a X.509 Certificate and Extract its Public Key

Demonstrates how to load an X.509 certificate and extract the public key. Chilkat supports many certificate encodings:

• DER (binary) encoded certificates (.crt/.cer)
• PEM (BASE64) encoded certificates (.pem)
• Load Certificates Directly from Windows Certificate Stores
• PFX/PKCS12 (.pfx/.p12)
• Java KeyStore (.jks)
• Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)

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#import <CkoCert.h>
#import <CkoPublicKey.h>

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

// Load a DER (binary) encoded certificate.
// To load from a .pem or .p7b, or any other file format that contains
// just one certificate, call LoadFromFile in exactly the same way.
// The LoadFromFile method automatically detects the format and loads the certificate.
BOOL success = [cert LoadFromFile: @"qa_data/certs/testCert.cer"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

// Get the public key:
CkoPublicKey *pubKey = [cert ExportPublicKey];
if (cert.LastMethodSuccess != YES) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

// Examine the key type.
// A PublicKey object can contain an RSA, ECC, or DSA public key.
// The KeyType property will contain "rsa", "ecc", or "dsa".
NSLog(@"%@%@",@"key type = ",pubKey.KeyType);