(C) Create XML Signature with Certificate's Private Key

Demonstrates how to create an XML digital signature using a certificate's RSA private key. This example loads the certificate from a PFX, and uses the cert's associated private key to sign. The public key is embedded in the XML signature as a ds:KeyInfo / ds:KeyValue / dsRSAKeyValue element.

This example requires Chilkat v9.5.0.71 or greater.

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#include <C_CkHttp.h>
#include <C_CkStringBuilder.h>
#include <C_CkCert.h>
#include <C_CkPrivateKey.h>
#include <C_CkXmlDSigGen.h>

void ChilkatSample(void)
    {
    const char *url;
    HCkHttp http;
    HCkStringBuilder sbSoapXml;
    BOOL success;
    HCkCert cert;
    HCkPrivateKey rsaKey;
    HCkXmlDSigGen xmlSigGen;

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

    // The SOAP XML to be signed in this example contains the following:

    // <?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>
    // 

    // The above XML is available at https://www.chilkatsoft.com/exampleData/soapToSign.xml
    // Fetch the XML and then sign it..

    url = "https://www.chilkatsoft.com/exampleData/soapToSign.xml";
    http = CkHttp_Create();
    sbSoapXml = CkStringBuilder_Create();
    success = CkHttp_QuickGetSb(http,url,sbSoapXml);
    if (success != TRUE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkHttp_Dispose(http);
        CkStringBuilder_Dispose(sbSoapXml);
        return;
    }

    // Load a PFX file containing the certificate + private key.
    cert = CkCert_Create();
    success = CkCert_LoadPfxFile(cert,"/somedir/myPfx.pfx","pfx_password");
    if (success != TRUE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkHttp_Dispose(http);
        CkStringBuilder_Dispose(sbSoapXml);
        CkCert_Dispose(cert);
        return;
    }

    // Get the RSA private key for signing...
    rsaKey = CkCert_ExportPrivateKey(cert);
    if (CkCert_getLastMethodSuccess(cert) != TRUE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkHttp_Dispose(http);
        CkStringBuilder_Dispose(sbSoapXml);
        CkCert_Dispose(cert);
        return;
    }

    // To create the XML digital signature (i.e. embed the signature within
    // the SOAP XML), we specify what is desired, and then call the method to 
    // create the XML signature.
    // 
    // For example, the application must provide the following:
    //     - Where to put the signature.
    //     - What to sign.
    //     - The algorithms to be used.
    //     - The key to be used for signing.
    // 

    xmlSigGen = CkXmlDSigGen_Create();

    // In this example, we're going to put the signature within the wsse:Security element.
    // To specify the location, set the SigLocation property to the XML path to this element,
    // using vertical bar characters to separate tags.
    CkXmlDSigGen_putSigLocation(xmlSigGen,"SOAP-ENV:Envelope|SOAP-ENV:Header|wsse:Security");

    // An XML digital signature contains one or more references.  These are references to the parts
    // of the XML document to be signed (a same document reference), or can be external references.
    // This example will add a single same-document reference.  We'll add a reference to the XML fragment
    // at SOAP-ENV:Body, which is indicated by providing the value of the "ID" attribute (where "ID" is case
    // insensitive).  For each same-document reference, we must also indicate the hash algorithm and XML canonicalization
    // algorithm to be used.  For this example we'll choose SHA-256 and Exclusive XML Canonicalization.
    CkXmlDSigGen_AddSameDocRef(xmlSigGen,"Body","sha256","EXCL_C14N","","");

    // Let's provide the RSA key to be used for signing:
    CkXmlDSigGen_SetPrivateKey(xmlSigGen,rsaKey);
    CkPrivateKey_Dispose(rsaKey);

    // We're leaving the following properties at their default values:
    // 
    //    - SigNamespacePrefix (default is "ds")
    //    - SigningAlg (for RSA keys. The default is PKCS1-v1_5, can be changed to RSASSA-PSS.)
    //    - SignedInfoCanonAlg  (default is EXCL_C14N)
    //    - SignedInfoDigestMethod (default is sha256)
    //    - KeyInfoType (default is "KeyValue", where the RSA public key is included in the Signature)

    // Note: Each Reference has it's own specified algorithms for XML canonicalization and hashing,
    // and the actual signature part (the SignedInfo) has it's own algorithms for the same.
    // They may or may not be the same.  In this example, we use Exclusive XML Canonicalization and SHA-256 throughout.

    // Finally, we're going to set one property that's optional, but commonly used.
    // It's the SignedInfoPrefixList.  In this case, we're using Exclusive Canonicalization, and the signature
    // will be placed in a location within the XML document where namespace prefixes are used in the ancestors.
    // Specifically, the "wsse" and "SOAP-ENV" namespace prefixes are used.
    CkXmlDSigGen_putSignedInfoPrefixList(xmlSigGen,"wsse SOAP-ENV");

    // OK, everything's specified, so let's create the XML digital signature:
    // This in-place signs the XML.  If successful, sbSoapXml will contain the 
    // XML with the digital signature at the specified location.
    success = CkXmlDSigGen_CreateXmlDSigSb(xmlSigGen,sbSoapXml);
    if (success != TRUE) {
        printf("%s\n",CkXmlDSigGen_lastErrorText(xmlSigGen));
        CkHttp_Dispose(http);
        CkStringBuilder_Dispose(sbSoapXml);
        CkCert_Dispose(cert);
        CkXmlDSigGen_Dispose(xmlSigGen);
        return;
    }

    // Examine the signed SOAP XML:
    printf("%s\n",CkStringBuilder_getAsString(sbSoapXml));

    // This is the signed SOAP XML.
    // Chilkat emits the Signature in compact form on a single line.  Whitespace in XML signatures
    // matters.  Chilkat's opinion is that writing the Signature without whitespace minimizes the chance
    // for problems with whatever software might be verifying the signature.

    // <?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"><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#"><InclusiveNamespaces xmlns="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="wsse SOAP-ENV"/></ds:CanonicalizationMethod><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/><ds:Reference URI="#Body"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>OwgHPZNfDkXnZsjpfzXqAcT3RV3HzmTsEy2bP44FJ0M=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>C+7FWngUpJ33Q1yq8uuscjCyPN2IO4cJhpMv03Jrrht1V+4gvJQLIBk6HHjo1uPQyfYj6zji3pg+fOyGUptp17CsRvjCzSpP35vB2lEzHeS8dcY8XfrEtTP/0FNn75LmhhkOPy0wjWkgDVbgzhXpEk9az8r8fQVTM3vrcmXT+WdMWJXKBRFt6PLAhsFt0scOFTWAkLGyCwygzimDKX2nT63TOit9BigtIx7fPRuMkbybMKCGGABq2DiEbvrPOiN3SUYpyMNR9KehRAGN+OWnESaDC6DhOvbKR88XHkM+GeaRe9PWdrRHrwGfp3qgolKjR/wFRSa1YGSBKAhDJFBcdg==</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></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>

    // Here's the signature part formatted for easier reading.
    // (Adding whitespace to the SignedInfo breaks the signature, so you wouldn't want to do this..)

    //     <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#">
    //                 <InclusiveNamespaces xmlns="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="wsse SOAP-ENV" />
    //             </ds:CanonicalizationMethod>
    //             <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256" />
    //             <ds:Reference URI="#Body">
    //                 <ds:Transforms>
    //                     <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
    //                 </ds:Transforms>
    //                 <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256" />
    //                 <ds:DigestValue>OwgHPZNfDkXnZsjpfzXqAcT3RV3HzmTsEy2bP44FJ0M=</ds:DigestValue>
    //             </ds:Reference>
    //         </ds:SignedInfo>
    //         <ds:SignatureValue>C+7FWngUp....BKAhDJFBcdg==</ds:SignatureValue>
    //         <ds:KeyInfo>
    //             <ds:KeyValue>
    //                 <ds:RSAKeyValue>
    //                     <ds:Modulus>sXeRhM55P13FbpNcXAMR....MYmDBjNAcibRw==</ds:Modulus>
    //                     <ds:Exponent>AQAB</ds:Exponent>
    //                 </ds:RSAKeyValue>
    //             </ds:KeyValue>
    //         </ds:KeyInfo>
    //     </ds:Signature>


    CkHttp_Dispose(http);
    CkStringBuilder_Dispose(sbSoapXml);
    CkCert_Dispose(cert);
    CkXmlDSigGen_Dispose(xmlSigGen);

    }