(C++) Create XML Digital Signature using Certificate on Smart Card

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Demonstrates how to load a certificate located on a smart card or USB token and then use it for creating an XML digital signature such that the cryptographic signing happens on the smart card.

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#include <CkScMinidriver.h>
#include <CkCert.h>
#include <CkXml.h>
#include <CkXmlDSigGen.h>
#include <CkStringBuilder.h>

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

    CkScMinidriver scmd;

    // Reader names (smart card readers or USB tokens) can be discovered
    // via List Readers or Find Smart Cards
    const char *readerName = "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0";
    bool success = scmd.AcquireContext(readerName);
    if (success == false) {
        std::cout << scmd.lastErrorText() << "\r\n";
        return;
    }

    // If successful, the name of the currently inserted smart card is available:
    std::cout << "Card name: " << scmd.cardName() << "\r\n";

    // If desired, perform regular PIN authentication with the smartcard.
    // For more details about smart card PIN authentication, see the Smart Card PIN Authentication Example
    int retval = scmd.PinAuthenticate("user","000000");
    if (retval != 0) {
        std::cout << "PIN Authentication failed." << "\r\n";
    }

    // You can find a cerficate using any of the following certificate parts:
    // "subjectDN" -- The full distinguished name of the cert.
    // "subjectDN_withTags" -- Same as above, but in a format that includes the subject part tags, such as the "CN=" in "CN=something"
    // "subjectCN" -- The common name part (CN) of the certificate's subject.
    // "serial" -- The certificate serial number.
    // "serial:issuerCN" -- The certificate serial number + the issuer's common name, delimited with a colon char.
    // These are the same certificate parts that can be retrieved by listing certificates on the smart card (or USB token).
    // See List Certificates on Smart Card Example
    const char *certPart = "subjectCN";
    const char *partValue = "PIVKey E42D60A759D39147A26E0AF2FB1183C5";

    // If the certificate is found, it is loaded into the cert object.
    CkCert cert;
    success = scmd.FindCert(certPart,partValue,cert);
    if (success == false) {
        std::cout << "Failed to find the certificate." << "\r\n";
        scmd.DeleteContext();
        return;
    }

    std::cout << "Successfully loaded the cert object from the smart card / USB token." << "\r\n";

    // Note: When successful, the cert object is internally linked to the ScMinidriver object's authenticated session.
    // The cert object can now be used to sign or do other cryptographic operations that occur on the smart card / USB token.
    // If your application calls PinDeauthenticate or DeleteContext, the cert will no longer be able to sign on the smart card
    // because the smart card ScMinidriver session will no longer be authenticated or deleted.

    // ------------------------------------------------------------------------------------------------------------
    // We have the certificate.  Now let's do the XML digital signature..

    // Create the following XML to be signed:

    // <?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>

    CkXml xml;
    xml.put_Tag("SOAP-ENV:Envelope");
    xml.AddAttribute("xmlns:SOAP-ENV","http://schemas.xmlsoap.org/soap/envelope/");
    xml.UpdateAttrAt("SOAP-ENV:Header|wsse:Security",true,"xmlns:wsse","http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd");
    xml.UpdateAttrAt("SOAP-ENV:Header|wsse:Security",true,"SOAP-ENV:mustUnderstand","1");
    xml.UpdateAttrAt("SOAP-ENV:Body",true,"xmlns:SOAP-SEC","http://schemas.xmlsoap.org/soap/security/2000-12");
    xml.UpdateAttrAt("SOAP-ENV:Body",true,"SOAP-SEC:id","Body");
    xml.UpdateAttrAt("SOAP-ENV:Body|z:FooBar",true,"xmlns:z","http://example.com");

    // Prepare for signing...
    CkXmlDSigGen gen;

    // Indicate where the Signature will be inserted.
    gen.put_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","sha1","EXCL_C14N","","");

    // (You can read about the SignedInfoPrefixList in the online reference documentation.  It's optional..)
    gen.put_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.put_KeyInfoType("X509Data");
    gen.put_X509Type("Certificate");

    // Note: Our certificate was loaded from the smartcard and is internally linked to the authenticated ScMinidriver session.
    // The signing will occur on the smart card using the chosen certificate.
    bool bUsePrivateKey = true;
    success = gen.SetX509Cert(cert,bUsePrivateKey);
    if (success != true) {
        std::cout << gen.lastErrorText() << "\r\n";
        return;
    }

    // Everything's specified.  Now create and insert the Signature
    CkStringBuilder sbXml;
    xml.GetXmlSb(sbXml);
    success = gen.CreateXmlDSigSb(sbXml);
    if (success != true) {
        std::cout << gen.lastErrorText() << "\r\n";
        return;
    }

    // Examine the XML with the digital signature inserted
    std::cout << sbXml.getAsString() << "\r\n";

    // ------------------------------------------------------------------------------------------------------------
    // Cleanup our ScMinidriver session...

    // When finished with operations that required authentication, you may if you wish, deauthenticate the session.
    success = scmd.PinDeauthenticate("user");
    if (success == false) {
        std::cout << scmd.lastErrorText() << "\r\n";
    }

    // Delete the context when finished with the card.
    success = scmd.DeleteContext();
    if (success == false) {
        std::cout << scmd.lastErrorText() << "\r\n";
    }
    }