(Visual FoxPro) 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.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lcUrl
LOCAL loHttp
LOCAL loSbSoapXml
LOCAL lnSuccess
LOCAL loCert
LOCAL loRsaKey
LOCAL loXmlSigGen

* 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..

lcUrl = "https://www.chilkatsoft.com/exampleData/soapToSign.xml"
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Http')
loHttp = CreateObject('Chilkat.Http')
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSbSoapXml = CreateObject('Chilkat.StringBuilder')
lnSuccess = loHttp.QuickGetSb(lcUrl,loSbSoapXml)
IF (lnSuccess <> 1) THEN
    ? loHttp.LastErrorText
    RELEASE loHttp
    RELEASE loSbSoapXml
    CANCEL
ENDIF

* Load a PFX file containing the certificate + private key.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cert')
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("/somedir/myPfx.pfx","pfx_password")
IF (lnSuccess <> 1) THEN
    ? loCert.LastErrorText
    RELEASE loHttp
    RELEASE loSbSoapXml
    RELEASE loCert
    CANCEL
ENDIF

* Get the RSA private key for signing...
loRsaKey = loCert.ExportPrivateKey()
IF (loCert.LastMethodSuccess <> 1) THEN
    ? loCert.LastErrorText
    RELEASE loHttp
    RELEASE loSbSoapXml
    RELEASE loCert
    CANCEL
ENDIF

* 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.
* 

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.XmlDSigGen')
loXmlSigGen = CreateObject('Chilkat.XmlDSigGen')

* 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.
loXmlSigGen.SigLocation = "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.
loXmlSigGen.AddSameDocRef("Body","sha256","EXCL_C14N","","")

* Let's provide the RSA key to be used for signing:
loXmlSigGen.SetPrivateKey(loRsaKey)
RELEASE loRsaKey

* 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.
loXmlSigGen.SignedInfoPrefixList = "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.
lnSuccess = loXmlSigGen.CreateXmlDSigSb(loSbSoapXml)
IF (lnSuccess <> 1) THEN
    ? loXmlSigGen.LastErrorText
    RELEASE loHttp
    RELEASE loSbSoapXml
    RELEASE loCert
    RELEASE loXmlSigGen
    CANCEL
ENDIF

* Examine the signed SOAP XML:
? loSbSoapXml.GetAsString()

* 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>

RELEASE loHttp
RELEASE loSbSoapXml
RELEASE loCert
RELEASE loXmlSigGen