Objective-C

Add a Detached Signature with a Separate Private Key

Demonstrates the Chilkat Mime.AddDetachedSignaturePk method, which creates a detached signature using a signer certificate and its separately supplied private key. The first argument is the Cert and the second is the PrivateKey.

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: Sometimes the certificate and its private key live apart — a .cer alongside a PEM key file, for instance — rather than bundled in a single PFX. This method pairs them explicitly for signing, whereas AddDetachedSignature expects a Cert that already provides its key. The result is the same multipart/signed message.

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Objective-C

#import <CkoMime.h>
#import <CkoCert.h>
#import <CkoPrivateKey.h>

BOOL success = NO;

CkoMime *mime = [[CkoMime alloc] init];
success = [mime SetBodyFromPlainText: @"This message will be signed."];
if (success == NO) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

//  Load the certificate and its private key separately.
CkoCert *cert = [[CkoCert alloc] init];
success = [cert LoadFromFile: @"qa_data/signer.cer"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

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

//  Create a detached signature when the certificate and private key are supplied separately.  The
//  1st argument is the signer certificate and the 2nd is its private key.
success = [mime AddDetachedSignaturePk: cert privateKey: privKey];
if (success == NO) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

success = [mime SaveMime: @"qa_output/signed.eml"];
if (success == NO) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

NSLog(@"%@",@"Detached signature added.");