(Objective-C) CoSign PKCS7/CMS Signed Data

See more Digital Signatures Examples

Demonstrates how to add a 2nd signature to a CMS SignedData. This is to add an additional signature, SignerInfo and certificate(s) to an existing CMS signed data.

In this example, we cosign an existing pdf.p7s

Note: The CoSign method is added in Chilkat v9.5.0.89.

Chilkat Objective-C Library Downloads MAC OS X (Cocoa) Libs iOS Libs

#import <CkoCrypt2.h>
#import <CkoCert.h>
#import <CkoBinData.h>

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

CkoCrypt2 *crypt = [[CkoCrypt2 alloc] init];
CkoCert *cert = [[CkoCert alloc] init];

// If loading from a smart card, set the smartcard PIN.
cert.SmartCardPin = @"0000";

// Load a certificate in some way, such as from a smart card.
// Chilkat provides other methods to load from a .pfx, .pem, or from the Windows certificate stores..
BOOL success = [cert LoadFromSmartcard: @""];
if (success == NO) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

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

// Load the file to be co-signed.
// NOTE:  This is to cosign a PDF file contained within a CMS (PKCS7) message.
// (In other words, the PDF is contained within the CMS SignedData, rather than the other way around
// where a CMS signature is contained within a PDF.  Use Chilkat's PDF class to sign a PDF, which is
// to embed a CMS signature within the PDF.)
CkoBinData *bd = [[CkoBinData alloc] init];
success = [bd LoadFile: @"qa_data/p7s/cosign/sample.pdf.p7s"];
if (success == NO) {
    NSLog(@"%@",@"Failed to load pdf.p7s input file.");
    return;
}

// bd2 will contain the co-signed result.
CkoBinData *bd2 = [[CkoBinData alloc] init];
success = [crypt CoSign: bd cert: cert bdOut: bd2];
if (success == NO) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

success = [bd WriteFile: @"qa_output/cosigned.pdf.p7s"];
if (success == NO) {
    NSLog(@"%@",@"Failed to save pdf.p7s output file.");
    return;
}

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