Objective-C

Specify a Certificate for Encrypted Email

Demonstrates the Chilkat Email.AddEncryptCert method, which explicitly specifies a certificate to use when sending encrypted email. Call it once per recipient certificate; ClearEncryptCerts clears the list. This example loads a recipient certificate, registers it, and enables encrypted sending.

Background: When encrypting to multiple people, each recipient needs to be able to decrypt with their own private key. S/MIME handles this by encrypting the message's one-time content key separately under each recipient's public certificate and including all of those wrapped keys in the message. AddEncryptCert is how you build that recipient list — one call per certificate — giving explicit control over exactly whose certificates are used rather than relying on automatic lookup.

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Objective-C

#import <CkoEmail.h>
#import <CkoCert.h>

BOOL success = NO;

//  Demonstrates the AddEncryptCert method, which explicitly specifies a certificate for
//  sending encrypted email.  Call it once per recipient certificate.  Use ClearEncryptCerts
//  to clear the list.

CkoEmail *email = [[CkoEmail alloc] init];
email.Subject = @"Encrypted email";
email.Body = @"Encrypted to the specified recipient certificate(s).";
email.From = @"alice@example.com";
[email AddTo: @"Bob" emailAddress: @"bob@example.com"];

//  Load a recipient certificate (public key) and add it to the encryption cert list.
CkoCert *cert = [[CkoCert alloc] init];
success = [cert LoadFromFile: @"qa_data/certs/recipient.cer"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return true;
}

success = [email AddEncryptCert: cert];
if (success == NO) {
    NSLog(@"%@",email.LastErrorText);
    return true;
}

//  Request encrypted sending.
email.SendEncrypted = YES;

NSLog(@"%@",@"Added the recipient's encryption certificate.");

//  Note: The path "qa_data/certs/recipient.cer" is a relative local filesystem path,
//  relative to the current working directory of the running application.