(Objective-C) PKCS11 XML Signature using Certificate and Private Key on Smart Card / USB Token

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Sample code showing how to use PKCS11 to create an XML digital signature with a certificate and private key stored on a smart card or USB token.

Note: This example requires Chilkat v9.5.0.96 or later.

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#import <CkoPkcs11.h>
#import <NSString.h>
#import <CkoCert.h>
#import <CkoXml.h>
#import <CkoXmlDSigGen.h>
#import <CkoStringBuilder.h>

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

// Note: Chilkat's PKCS11 implementation runs on Windows, Linux, Mac OS X, and other supported operating systems.

CkoPkcs11 *pkcs11 = [[CkoPkcs11 alloc] init];

// This example is tested on Windows using a Giesecke and Devrient Sm@rtCafe Expert 3.2 smart card.
// You will use the DLL (or shared lib) provided by your smart card vendor, or a DLL compatible with your smart card.
// On Windows, if the DLL is located in C:\Windows\System32, specify only the filename.
// Otherwise provide the full path.
pkcs11.SharedLibPath = @"aetpkss1.dll";

// Make it an authenticated session by calling Login.
int userType = 1;
// Make sure to use the correct PIN for your smart card..
NSString *pin = @"0000";

BOOL success = [pkcs11 QuickSession: [NSNumber numberWithInt: userType] pin: pin];
if (success == NO) {
    NSLog(@"%@",pkcs11.LastErrorText);
    return;
}

// Get the certificate (on the smart card) that has a private key.
CkoCert *cert = [[CkoCert alloc] init];
success = [pkcs11 FindCert: @"privateKey" partValue: @"" cert: cert];
if (success == YES) {
    NSLog(@"%@%@",@"Cert with private key: ",cert.SubjectCN);
}
else {
    NSLog(@"%@",@"No certificates having a private key were found.");
    success = [pkcs11 CloseSession];
    return;
}

// --------------------------------------------------------------------------
// At this point, we have the cert to be used for signing.
// Our XML signing code is the same as for a cert obtained from any other source..

// First generate the following XML to be signed:
// Use this online tool to generate code from sample XML: 
// Generate Code to Create XML

// <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
// <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
//     <SOAP-ENV:Header>
//         <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" SOAP-ENV:mustUnderstand="1"></wsse:Security>
//     </SOAP-ENV:Header>
//     <SOAP-ENV:Body xmlns:SOAP-SEC="http://schemas.xmlsoap.org/soap/security/2000-12" SOAP-SEC:id="Body">
//         <z:FooBar xmlns:z="http://example.com" />
//     </SOAP-ENV:Body>
// </SOAP-ENV:Envelope>

CkoXml *xml = [[CkoXml alloc] init];
xml.Tag = @"SOAP-ENV:Envelope";
[xml AddAttribute: @"xmlns:SOAP-ENV" value: @"http://schemas.xmlsoap.org/soap/envelope/"];
[xml UpdateAttrAt: @"SOAP-ENV:Header|wsse:Security" autoCreate: YES attrName: @"xmlns:wsse" attrValue: @"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"];
[xml UpdateAttrAt: @"SOAP-ENV:Header|wsse:Security" autoCreate: YES attrName: @"SOAP-ENV:mustUnderstand" attrValue: @"1"];
[xml UpdateAttrAt: @"SOAP-ENV:Body" autoCreate: YES attrName: @"xmlns:SOAP-SEC" attrValue: @"http://schemas.xmlsoap.org/soap/security/2000-12"];
[xml UpdateAttrAt: @"SOAP-ENV:Body" autoCreate: YES attrName: @"SOAP-SEC:id" attrValue: @"Body"];
[xml UpdateAttrAt: @"SOAP-ENV:Body|z:FooBar" autoCreate: YES attrName: @"xmlns:z" attrValue: @"http://example.com"];

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

// Indicate where the Signature will be inserted.
gen.SigLocation = @"SOAP-ENV:Envelope|SOAP-ENV:Header|wsse:Security";

// Add a reference to the fragment of the XML to be signed.

// Note: "Body" refers to the XML element having an "id" equal to "Body", where "id" is case insensitive
// and where any namespace might qualify the attribute.  In this case, the SOAP-ENV:Body fragment is signed
// NOT because the tag = "Body", but because it has SOAP-SEC:id="Body"
[gen AddSameDocRef: @"Body" digestMethod: @"sha1" canonMethod: @"EXCL_C14N" prefixList: @"" refType: @""];

// (You can read about the SignedInfoPrefixList in the online reference documentation.  It's optional..)
gen.SignedInfoPrefixList = @"wsse SOAP-ENV";

// Provide the private key for signing via the certificate, and indicate that
// we want the base64 of the certificate embedded in the KeyInfo.
gen.KeyInfoType = @"X509Data";
gen.X509Type = @"Certificate";

BOOL bUsePrivateKey = YES;
success = [gen SetX509Cert: cert usePrivateKey: bUsePrivateKey];
if (success != YES) {
    NSLog(@"%@",gen.LastErrorText);
    success = [pkcs11 CloseSession];
    return;
}

// Everything's specified.  Now create and insert the Signature
CkoStringBuilder *sbXml = [[CkoStringBuilder alloc] init];
xml.EmitCompact = YES;
[xml GetXmlSb: sbXml];

success = [gen CreateXmlDSigSb: sbXml];
if (success != YES) {
    NSLog(@"%@",gen.LastErrorText);
    success = [pkcs11 CloseSession];
    return;
}

// Examine the XML with the digital signature inserted
NSLog(@"%@",[sbXml GetAsString]);

// --------------------------------------------------------------------------

// Revert to an unauthenticated session by calling Logout.
success = [pkcs11 Logout];
if (success == NO) {
    NSLog(@"%@",pkcs11.LastErrorText);
    success = [pkcs11 CloseSession];
    return;
}

// When finished, close the session.
// It is important to close the session (memory leaks will occur if the session is not properly closed).
success = [pkcs11 CloseSession];
if (success == NO) {
    NSLog(@"%@",pkcs11.LastErrorText);
    return;
}

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