Objective-C

Export a Public Key as PEM

Demonstrates the Chilkat PublicKey.GetPem method, which returns the public key in PEM format. The only argument selects the underlying DER representation: true prefers the traditional PKCS #1 form (RSA), false uses the SubjectPublicKeyInfo form.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: PEM is the most portable way to share a public key — the Base64 text block most tooling reads. The boolean picks the encoding: false produces the modern, algorithm-independent PUBLIC KEY (SubjectPublicKeyInfo), which is the usual choice; true produces the older RSA-specific RSA PUBLIC KEY for tools that require it. A public key is not sensitive, so the PEM can be distributed openly.

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Objective-C

#import <CkoPublicKey.h>
#import <NSString.h>

BOOL success = NO;

//  Load a public key to export.  LoadFromFile inspects the content, so it accepts DER, PEM, XML,
//  JWK, and other supported representations.
CkoPublicKey *pubKey = [[CkoPublicKey alloc] init];
success = [pubKey LoadFromFile: @"qa_data/public.pem"];
if (success == NO) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

//  Export the public key in PEM format.  The argument selects the underlying DER representation:
//  true prefers the traditional PKCS #1 form (RSA), false uses the SubjectPublicKeyInfo form.
BOOL preferPkcs1 = NO;
NSString *pem = [pubKey GetPem: preferPkcs1];
if (pubKey.LastMethodSuccess == NO) {
    NSLog(@"%@",pubKey.LastErrorText);
    return;
}

NSLog(@"%@",pem);