Objective-C

Create XML Signature with External Data Reference

See more XML Digital Signatures Examples

Demonstrates how to create an XML digital signature where the data is external. In this case, the data is a JPG file.

This example requires Chilkat v9.5.0.69 or greater.

Objective-C

#import <NSString.h>
#import <CkoHttp.h>
#import <CkoStringBuilder.h>
#import <CkoPrivateKey.h>
#import <CkoXmlDSigGen.h>
#import <CkoBinData.h>

BOOL success = NO;

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

// This example inserts an XML signature in the following XML:

// <?xml version="1.0" encoding="UTF-8" standalone="no"?>
// <abc>
//   <xyz>
//     <jpg>
//         <name>starfish.jpg</name>
//         <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
//     </jpg>
//   </xyz>
// </abc>

// The above XML is available at https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml
// First fetch the XML:

NSString *url = @"https://www.chilkatsoft.com/exampleData/addSignatureToThis.xml";
CkoHttp *http = [[CkoHttp alloc] init];
CkoStringBuilder *sbXml = [[CkoStringBuilder alloc] init];
success = [http QuickGetSb: url sbContent: sbXml];
if (success != YES) {
    NSLog(@"%@",http.LastErrorText);
    return;
}

// We'll use an RSA private key for signing.  
CkoPrivateKey *rsaKey = [[CkoPrivateKey alloc] init];
success = [rsaKey LoadPemFile: @"qa_data/rsa/rsaPrivKey_pkcs8.pem"];
if (success != YES) {
    NSLog(@"%@",rsaKey.LastErrorText);
    return;
}

CkoXmlDSigGen *xmlSigGen = [[CkoXmlDSigGen alloc] init];

// Indicate were the Signature will be inserted:
xmlSigGen.SigLocation = @"abc|xyz|jpg";

// Provide the RSA key to be used for signing:
[xmlSigGen SetPrivateKey: rsaKey];

// Fetch the JPG image data.
NSString *jpgUrl = @"https://www.chilkatsoft.com/images/starfish.jpg";
CkoBinData *jpgData = [[CkoBinData alloc] init];
success = [http QuickGetBd: jpgUrl binData: jpgData];
if (success != YES) {
    NSLog(@"%@",http.LastErrorText);
    return;
}

// Add the external data reference:
[xmlSigGen AddExternalBinaryRef: jpgUrl content: jpgData digestMethod: @"sha256" refType: @""];

// Create the XML digital signature:
success = [xmlSigGen CreateXmlDSigSb: sbXml];
if (success != YES) {
    NSLog(@"%@",xmlSigGen.LastErrorText);
    return;
}

// Examine the XML that now contains the Signature:
NSLog(@"%@",[sbXml GetAsString]);

// <?xml version="1.0" encoding="UTF-8" standalone="no"?>
// <abc>
//   <xyz>
//     <jpg>
//         <name>starfish.jpg</name>
//         <url>https://www.chilkatsoft.com/images/starfish.jpg</url>
//     <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/><ds:Reference URI="https://www.chilkatsoft.com/images/starfish.jpg"><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>AOU810yJV5Np/DnO29qpObqiTSTTCDvxGsX5ayiTYXI=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>ApHRr6nilNrzt3dLveC9zlPoSllaCMfHsbAwr+vYBPkHkJ4wD5LzDDhi1tSJZAAeTckmvSqIG3Wi0rgXQiSM644MD3coBFx4QgrY+GZ+XJJE2Y0Ye3VvaQBiRdUW3INGsW4GLubncgQk5JhuAQjo6O/GKpfEuYqUJj/6CLHLQwMPwbZ2043ykgzuPFoOZf6EydJMBAn1ORMvrpUn+zuA9UngOTGap6eWE4CeiNx23BRC2wSztbUjdCLcqXvgiYu/v0tBNaTcwy7b6+IFtwv/lNUUBUQJ/3p+aErzFn3wLeH3yeqpDCU0U6Dqu5SS1jYupcWWsLHJjYnj2066DPJi/g==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:RSAKeyValue><ds:Modulus>sXeRhM55P13FbpNcXAMR3olbw2Wa6keZIHu5YTZYUBTlYWId+pNiwUz3zFIEo+0IfYR0H27ybIycQO+1IIzJofUFNMAL3tZps2OKPlsjuCPls6kXpXhv/gvhux8LrCtp4PcKWqJ6QVOZKChc7WAx40qFWzHi57ueqRTv3x0kESqGg/VjsqyTEvb55psJO2RsfhLT7+YVh3hImRM3RDaJdkTkPuOxeFyT6N7VXD09329sLuS3QkUbE9zEKDnz9X3d8dEQdJhSI9ba5fxl8R7fu8pB67ElfzFml96X1jLFtzy1pzOT5Fc4ROcaqlYckVzdBq9sxezm6MYmDBjNAcibRw==</ds:Modulus><ds:Exponent>AQAB</ds:Exponent></ds:RSAKeyValue></ds:KeyValue></ds:KeyInfo></ds:Signature></jpg>
//   </xyz>
// </abc>
//