(Objective-C) ConvertToSignedPk

Demonstrates how to digitally sign MIME to create an "opaque" signature. The MIME is converted to an application/x-pkcs7-mime which is a PKCS7 signature that includes both the original MIME message and the signature. This is different than AddDetachedSignaturePk, where the signature is appended to the MIME. This example demonstrates how to use the certificate and its corresponding private key when they are stored in separate files -- a .cer for the certificate, and a .pem for the private key.

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

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

CkoMime *mime = [[CkoMime alloc] init];

// Load the certificate from a .cer file.
CkoCert *cert = [[CkoCert alloc] init];
BOOL success = [cert LoadFromFile: @"aaworkarea/myCert.cer"];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

// Load the private key from an encrypted PEM file.
// (A private key can be loaded from other file formats also..)
CkoPrivateKey *privKey = [[CkoPrivateKey alloc] init];
success = [privKey LoadEncryptedPemFile: @"aaworkarea/myPrivateKey.pem" password: @"myPassword"];
if (success == NO) {
    NSLog(@"%@",privKey.LastErrorText);
    return;
}

success = [mime SetBodyFromPlainText: @"This is the plain-text MIME body."];

// Convert the MIME to application/x-pkcs7-mime, which
// is PKCS7 containing both the original content and the signature.
success = [mime ConvertToSignedPk: cert privateKey: privKey];
if (success == NO) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

// Save the S/MIME to a file.
success = [mime SaveMime: @"aaworkarea/opaqueSignedMime.txt"];
if (success == NO) {
    NSLog(@"%@",mime.LastErrorText);
    return;
}

NSLog(@"%@",@"success!");