(PureBasic) Create XML Digital Signature using a ECDSA Key

Demonstrates how to create an XML digital signature using a ECDSA key.

This example requires Chilkat v9.5.0.69 or greater.

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IncludeFile "CkXmlDSigGen.pb"
IncludeFile "CkHttp.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkPrivateKey.pb"
IncludeFile "CkXmlDSig.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

    ; This example uses an ECDSA private key for signing.  
    ; There are many ways to load an ECDSA private key using Chilkat.  This example
    ; will load from an unencrypted PEM file.

    ; For your convenience, Chilkat put this sample ECDSA PEM here:  https://www.chilkatsoft.com/exampleData/secp256r1-key.zip
    ecKey.i = CkPrivateKey::ckCreate()
    If ecKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPrivateKey::ckLoadPemFile(ecKey,"qa_data/ecc/secp256r1-key.pem")
    If success <> 1
        Debug CkPrivateKey::ckLastErrorText(ecKey)
        CkHttp::ckDispose(http)
        CkStringBuilder::ckDispose(sbSoapXml)
        CkPrivateKey::ckDispose(ecKey)
        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, the Signature will be placed 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.  A given reference
    ; can be a same-document reference (to an XML fragment), or an external reference.
    ; 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 ECDSA key to be used for signing:
    CkXmlDSigGen::ckSetPrivateKey(xmlSigGen,ecKey)

    ; We're leaving the following properties at their default values:
    ; 
    ;    - SigNamespacePrefix (default is "ds")
    ;    - SignedInfoCanonAlg  (default is EXCL_C14N)
    ;    - SignedInfoDigestMethod (default is sha256)
    ;    - KeyInfoType (default is "KeyValue", where the ECDSA public key is included in the Signature)

    ; Note: Each Reference specifies its own algorithms for XML canonicalization and hashing.
    ; The SignedInfo part also has specified hash and canonicalization algorithms, which may be different
    ; than the algorithms used in the References.
    ; 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)
        CkPrivateKey::ckDispose(ecKey)
        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#ecdsa-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>jmPSGgtirHSjjcs/o0NIDwwvy4aFBCEosSN+XP5NLVuGpRYnS2EM7mItiw6TKmESAoJYV23ZN4pZ9BFRKSvZqw==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:ECKeyValue xmlns="http://www.w3.org/2009/xmldsig11#"><ds:NamedCurve URI="urn:oid:1.2.840.10045.3.1.7" /><ds:PublicKey>BOVKaiLPKEDChhkA64UEBOXTv/VFHnhrUPN+bXqCvEl7rroAYpH5tKzbiGTtMSlp4JO9Pxg44zeX7EoWDvOrpD0=</ds:PublicKey></ds:ECKeyValue></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>

    ; The above signed XML contains the ECDSA public key in the ECKeyValue fragment (within the ds:KeyInfo).
    ; The signature can easily be verified like this:

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

    ; First load the XML containing the signature(s) to be verified.
    success = CkXmlDSig::ckLoadSignatureSb(verifier,sbSoapXml)
    If success <> 1
        Debug CkXmlDSig::ckLastErrorText(verifier)
        CkHttp::ckDispose(http)
        CkStringBuilder::ckDispose(sbSoapXml)
        CkPrivateKey::ckDispose(ecKey)
        CkXmlDSigGen::ckDispose(xmlSigGen)
        CkXmlDSig::ckDispose(verifier)
        ProcedureReturn
    EndIf

    bVerified.i = CkXmlDSig::ckVerifySignature(verifier,1)
    If bVerified <> 1
        Debug CkXmlDSig::ckLastErrorText(verifier)
    EndIf

    Debug "Signature verified = " + Str(bVerified)


    CkHttp::ckDispose(http)
    CkStringBuilder::ckDispose(sbSoapXml)
    CkPrivateKey::ckDispose(ecKey)
    CkXmlDSigGen::ckDispose(xmlSigGen)
    CkXmlDSig::ckDispose(verifier)


    ProcedureReturn
EndProcedure