Objective-C

Add a Detached Signature (Header Placement Control)

Demonstrates the Chilkat Mime.AddDetachedSignature2 method, which creates the same multipart/signed structure as AddDetachedSignature, with a second argument controlling whether the existing message header fields are transferred to the new outer entity.

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: Signing wraps the content in a new outer multipart/signed, which raises the question of where the message-level headers (Subject, From, To) should live. This variant lets you choose: transfer them up to the outer entity so the signed message looks like a normal email, or leave them on the inner part. Transferring is typical for email; the finer control matters when the signed entity is embedded in a larger structure.

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Objective-C

#import <CkoMime.h>
#import <NSString.h>
#import <CkoCert.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 signing certificate (which must have access to its private key) from a PFX file.
//  The PFX password should come from a secure source rather than being hard-coded.
NSString *pfxPassword = @"myPfxPassword";
CkoCert *cert = [[CkoCert alloc] init];
success = [cert LoadPfxFile: @"qa_data/signer.pfx" password: pfxPassword];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

//  AddDetachedSignature2 is the same as AddDetachedSignature, but the 2nd argument controls whether
//  the existing message header fields are transferred to the new outer multipart/signed entity.
BOOL transferHeaderFields = YES;
success = [mime AddDetachedSignature2: cert transferHeaderFields: transferHeaderFields];
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 (headers transferred).");