(PureBasic) 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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IncludeFile "CkCert.pb"
IncludeFile "CkHttp.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkPrivateKey.pb"
IncludeFile "CkXmlDSigGen.pb"

Procedure ChilkatExample()

    ; 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.s = "https://www.chilkatsoft.com/exampleData/soapToSign.xml"
    http.i = CkHttp::ckCreate()
    If http.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    sbSoapXml.i = CkStringBuilder::ckCreate()
    If sbSoapXml.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i = CkHttp::ckQuickGetSb(http,url,sbSoapXml)
    If success <> 1
        Debug CkHttp::ckLastErrorText(http)
        CkHttp::ckDispose(http)
        CkStringBuilder::ckDispose(sbSoapXml)
        ProcedureReturn
    EndIf

    ; Load a PFX file containing the certificate + private key.
    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkCert::ckLoadPfxFile(cert,"/somedir/myPfx.pfx","pfx_password")
    If success <> 1
        Debug CkCert::ckLastErrorText(cert)
        CkHttp::ckDispose(http)
        CkStringBuilder::ckDispose(sbSoapXml)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; Get the RSA private key for signing...
    rsaKey.i = CkCert::ckExportPrivateKey(cert)
    If CkCert::ckLastMethodSuccess(cert) <> 1
        Debug CkCert::ckLastErrorText(cert)
        CkHttp::ckDispose(http)
        CkStringBuilder::ckDispose(sbSoapXml)
        CkCert::ckDispose(cert)
        ProcedureReturn
    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.
    ; 

    xmlSigGen.i = CkXmlDSigGen::ckCreate()
    If xmlSigGen.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; 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::setCkSigLocation(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::ckAddSameDocRef(xmlSigGen,"Body","sha256","EXCL_C14N","","")

    ; Let's provide the RSA key to be used for signing:
    CkXmlDSigGen::ckSetPrivateKey(xmlSigGen,rsaKey)
    CkPrivateKey::ckDispose(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::setCkSignedInfoPrefixList(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::ckCreateXmlDSigSb(xmlSigGen,sbSoapXml)
    If success <> 1
        Debug CkXmlDSigGen::ckLastErrorText(xmlSigGen)
        CkHttp::ckDispose(http)
        CkStringBuilder::ckDispose(sbSoapXml)
        CkCert::ckDispose(cert)
        CkXmlDSigGen::ckDispose(xmlSigGen)
        ProcedureReturn
    EndIf

    ; Examine the signed SOAP XML:
    Debug CkStringBuilder::ckGetAsString(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::ckDispose(http)
    CkStringBuilder::ckDispose(sbSoapXml)
    CkCert::ckDispose(cert)
    CkXmlDSigGen::ckDispose(xmlSigGen)


    ProcedureReturn
EndProcedure