Objective-C

Save a Private Key as an Encrypted PKCS #8 DER File

Demonstrates the Chilkat PrivateKey.SavePkcs8EncryptedFile method, which saves the key as password-protected PKCS #8 DER. The first argument is the password and the second is the destination path. The cipher is selected by Pkcs8EncryptAlg.

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: This is the recommended way to persist a key to disk: the binary .der is encrypted under a passphrase, so a stolen file is useless without it. Reach for it whenever a key is stored or shipped. Choose the encryption cipher with Pkcs8EncryptAlg and source the password securely.

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Objective-C

#import <CkoPrivateKey.h>
#import <NSString.h>

BOOL success = NO;

//  Load a private key to export.
CkoPrivateKey *privKey = [[CkoPrivateKey alloc] init];
success = [privKey LoadPemFile: @"qa_data/private.pem"];
if (success == NO) {
    NSLog(@"%@",privKey.LastErrorText);
    return;
}

//  The key password is not hard-coded in a real application; obtain it from an interactive
//  prompt, environment variable, or a secrets vault.
NSString *password = @"myKeyPassword";

//  Save as password-protected PKCS #8 DER.  The 1st argument is the password and the 2nd is the
//  destination path.  The cipher is selected by the Pkcs8EncryptAlg property.
success = [privKey SavePkcs8EncryptedFile: password path: @"qa_output/private_pkcs8_enc.der"];
if (success == NO) {
    NSLog(@"%@",privKey.LastErrorText);
    return;
}

NSLog(@"%@",@"Saved (encrypted).");