(C# UWP/WinRT) 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.

Note: This functionality was introduced in Chilkat v9.5.0.87.

Note: The ScMinidriver functionality is for Windows-only because ScMinidriver DLLs only exist on Windows. In the next version, Chilkat will be releasing a Pkcs11 class to support Linux, MacOSX, and possibly other operating systems.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

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

Chilkat.ScMinidriver scmd = new Chilkat.ScMinidriver();

// Reader names (smart card readers or USB tokens) can be discovered
// via List Readers or Find Smart Cards
string readerName = "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0";
bool success = scmd.AcquireContext(readerName);
if (success == false) {
    Debug.WriteLine(scmd.LastErrorText);
    return;
}

// If successful, the name of the currently inserted smart card is available:
Debug.WriteLine("Card name: " + scmd.CardName);

// 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) {
    Debug.WriteLine("PIN Authentication failed.");
}

// 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
string certPart = "subjectCN";
string partValue = "PIVKey E42D60A759D39147A26E0AF2FB1183C5";

// If the certificate is found, it is loaded into the cert object.
Chilkat.Cert cert = new Chilkat.Cert();
success = scmd.FindCert(certPart,partValue,cert);
if (success == false) {
    Debug.WriteLine("Failed to find the certificate.");
    scmd.DeleteContext();
    return;
}

Debug.WriteLine("Successfully loaded the cert object from the smart card / USB token.");

// 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>

Chilkat.Xml xml = new Chilkat.Xml();
xml.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...
Chilkat.XmlDSigGen gen = new Chilkat.XmlDSigGen();

// 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","sha1","EXCL_C14N","","");

// (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";

// 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) {
    Debug.WriteLine(gen.LastErrorText);
    return;
}

// Everything's specified.  Now create and insert the Signature
Chilkat.StringBuilder sbXml = new Chilkat.StringBuilder();
xml.GetXmlSb(sbXml);
success = gen.CreateXmlDSigSb(sbXml);
if (success != true) {
    Debug.WriteLine(gen.LastErrorText);
    return;
}

// Examine the XML with the digital signature inserted
Debug.WriteLine(sbXml.GetAsString());

// ------------------------------------------------------------------------------------------------------------
// 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) {
    Debug.WriteLine(scmd.LastErrorText);
}

// Delete the context when finished with the card.
success = scmd.DeleteContext();
if (success == false) {
    Debug.WriteLine(scmd.LastErrorText);
}