Objective-C

Create PEM-encoded PKCS#7 Detached Signature

See more Digital Signatures Examples

Demonstrates how to create a PKCS7 PEM-encoded object containing a detached signature. Objective-C

#import <CkoCert.h>
#import <CkoCrypt2.h>
#import <NSString.h>
#import <CkoStringBuilder.h>

BOOL success = NO;

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

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

//  Load the cert and private key.
success = [cert LoadPfxFile: @"qa_data/pfx/myCertAndKey.p12" password: @"password"];
if (success != YES) {
    NSLog(@"%@",cert.LastErrorText);
    return;
}

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

success = [crypt SetSigningCert: cert];
if (success != YES) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

//  Use SHA-256
crypt.HashAlgorithm = @"sha256";

//  Hash the utf-8 byte representation of the string
crypt.Charset = @"utf-8";

//  Return the result in base64
crypt.EncodingMode = @"base64Mime";

//  Sign some text to create a detached signature (i.e. a signature that does not include the signed data)
NSString *textToSign = @"This is the text to be hashed and signed.";
NSString *sigBase64 = [crypt SignStringENC: textToSign];
if (crypt.LastMethodSuccess != YES) {
    NSLog(@"%@",crypt.LastErrorText);
    return;
}

NSLog(@"%@",sigBase64);

//  The result:

//  MIIWbgYJKoZIhvcNAQcCoIIWXzCCFlsCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
//  ghMXMIIFuzCCA6OgAwIBAgIIVwoRl0LE48wwDQYJKoZIhvcNAQELBQAwazELMAkGA1UEBhMCSVQx
//  ...
//  ...

//  If we want it in PEM format with just LF line-endings:
CkoStringBuilder *sb = [[CkoStringBuilder alloc] init];
//  Just LF line endings, not CRLF.
BOOL crlf = NO;
[sb AppendLine: @"-----BEGIN PKCS7-----" crlf: crlf];
[sb Append: sigBase64];
[sb AppendLine: @"-----END PKCS7-----" crlf: crlf];
[sb ToLF];

//  Save to a file.
[sb WriteFile: @"c:/temp/qa_output/sig.pem" charset: @"utf-8" emitBom: NO];

//  Examine..
NSLog(@"%@",[sb GetAsString]);

//  Result is:

//  -----BEGIN PKCS7-----
//  MIIWbgYJKoZIhvcNAQcCoIIWXzCCFlsCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
//  ghMXMIIFuzCCA6OgAwIBAgIIVwoRl0LE48wwDQYJKoZIhvcNAQELBQAwazELMAkGA1UEBhMCSVQx
//  DjAMBgNVBAcMBU1pbGFuMSMwIQYDVQQKDBpBY3RhbGlzIFMucC5BLi8wMzM1ODUyMDk2NzEnMCUG
//  A1UEAwweQWN0YWxpcyBBdXRoZW50aWNhdGlvbiBSb290IENBMB4XDTExMDkyMjExMjIwMloXDTMw
//  MDkyMjExMjIwMlowazELMAkGA1UEBhMCSVQxDjAMBgNVBAcMBU1pbGFuMSMwIQYDVQQKDBpBY3Rh
//  bGlzIFMucC5BLi8wMzM1ODUyMDk2NzEnMCUGA1UEAwweQWN0YWxpcyBBdXRoZW50aWNhdGlvbiBS
//  b290IENBMIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAp8bEpSmkLO/lGMWwUKNvUTuf
//  ClrJwkg4CsIcoBh/kbWHuUA/3R1oHwiD1S0eiKD4j1aPbZkCkpAW1V8IbInX4ay8IMKx4INRimlN
//  AJZaby/ARH6jDuSRzVju3PvHHkVH3Se5CAGfpiEd9UEtL0z9KK3giq0itFZljoZUj5NDKd45Rnij
//  MCO6zfB9E1fAXdKDa0hMxKufgFpbOr3JpyI/gCczWw63igxdBzcIy2zSekciRDXFzMwujt0q7bd9
//  ...
//  ...
//  -----END PKCS7-----