(Objective-C) POP3 Verify Signed (S/MIME) Email

Demonstrates how to download and verify digitally signed S/MIME email.

Note: This example requires Chilkat v11.0.0 or greater.

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

BOOL success = NO;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

CkoMailMan *mailman = [[CkoMailMan alloc] init];

// Set the POP3 server's hostname
mailman.MailHost = @"pop.example.com";

// Set the POP3 login/password.
mailman.PopUsername = @"myLogin";
mailman.PopPassword = @"myPassword";

CkoStringTable *stUidls = [[CkoStringTable alloc] init];
success = [mailman FetchUidls: stUidls];
if (success == NO) {
    NSLog(@"%@",mailman.LastErrorText);
    return;
}

CkoEmail *email = [[CkoEmail alloc] init];
CkoCert *cert = [[CkoCert alloc] init];

int count = [stUidls.Count intValue];
int i = 0;
while (i < count) {
    // Download the full email.
    success = [mailman FetchByUidl: [stUidls StringAt: [NSNumber numberWithInt: i]] headerOnly: NO numBodyLines: [NSNumber numberWithInt: 0] email: email];
    if (success == NO) {
        NSLog(@"%@",mailman.LastErrorText);
        return;
    }

    NSLog(@"%d",i);
    NSLog(@"%@%@",@"From: ",email.From);
    NSLog(@"%@%@",@"Subject: ",email.Subject);

    // The security layers of signed and/or encrypted emails
    // are automatically "unwrapped" when loaded into
    // a Chilkat email object.
    // An application only needs to check to see if an email
    // was received signed or encrypted, and then examine
    // the success/failure.  For example:
    if (email.ReceivedSigned == YES) {

        NSLog(@"%@",@"This email was signed.");

        // Check to see if the signatures were verified.
        if (email.SignaturesValid == YES) {
            NSLog(@"%@",@"Digital signature(s) verified.");
            NSLog(@"%@%@",@"Signer: ",email.SignedBy);

            success = [email LastSignerCert: [NSNumber numberWithInt: 0] cert: cert];
            if (success == NO) {
                NSLog(@"%@",email.LastErrorText);
                return;
            }

            NSLog(@"%@%@",@"Signing cert: ",cert.SubjectCN);
        }

    }
    else {
        NSLog(@"%@",@"Digital signature verification failed.");
    }

    i = i + 1;
}

[mailman Pop3EndSession];