(Objective-C) Get Certificate User Principal Name (UPN)

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Demonstrates how to get a certificate's UPN from the SAN (Subject Alternative Name). Most certificates do not have a UPN. This example only applies to those certificates that have a User Principal Name.

Note: This example requires Chilkat v9.5.0.90 or greater due to fixes made in getting the UPN from the SAN.

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#import <CkoCert.h>
#import <CkoXml.h>
#import <NSString.h>

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

BOOL success = [cert LoadFromFile: @"qa_data/certs/sample.cer"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

CkoXml *xml = [[CkoXml alloc] init];
[xml LoadXml: cert.SubjectAlternativeName];
NSLog(@"%@",[xml GetXml]);

// A certificate with a User Principal Name in the SAN might have this:

// <SubjectAltName>
//     <rfc822Name>joe@example.com</rfc822Name>
//     <name type="oid" oid="1.3.6.1.4.1.311.20.2.3">joe@example.com</name>
// </SubjectAltName>

// The OID 1.3.6.1.4.1.311.20.2.3 is for the User Principal Name.
NSString *upn = [xml ChilkatPath: @"/A/name,oid,1.3.6.1.4.1.311.20.2.3|*"];
if (xml.LastMethodSuccess == NO) {
    NSLog(@"%@",@"No user principle name.");
}
else {
    NSLog(@"%@%@",@"User Principle Name = ",upn);
}