Xbase++

Create/Verify XML Signature with External Text Reference

See more XML Digital Signatures Examples

Demonstrates how to create an XML digital signature where the referenced data is external. In this case, the data is a text file located at the following URL: https://www.chilkatsoft.com/helloWorld.txt Xbase++

LOCAL nSuccess
LOCAL oXml
LOCAL oCert
LOCAL oGen
LOCAL oHttp
LOCAL oSbExternalTxt
LOCAL nBUsePrivateKey
LOCAL oSbXml
LOCAL oVerifier
LOCAL oSbExternalData
LOCAL nNumRefs
LOCAL i
LOCAL nBExternal
LOCAL cUri
LOCAL nBVerified

nSuccess := 0

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

//  This example inserts an XML signature into the following XML:

//  <?xml version="1.0" encoding="UTF-8" standalone="no"?>
//  <abc>
//    <xyz>
//  	<name>helloWorld.txt</name>
//  	<url>https://www.chilkatsoft.com/helloWorld.txt</url>
//    </xyz>
//  </abc>

//  Build the above XML to be signed.
oXml := CreateObject("Chilkat.Xml")
oXml:Tag := "abc"
oXml:UpdateChildContent("xyz|name", "helloWorld.txt")
oXml:UpdateChildContent("xyz|url", "https://www.chilkatsoft.com/helloWorld.txt")

oCert := CreateObject("Chilkat.Cert")

nSuccess := oCert:LoadPfxFile("qa_data/pfx/test_secret.pfx", "secret")
IF (nSuccess == 0)
    ? oCert:LastErrorText
    oXml:destroy()
    oCert:destroy()
    RETURN
ENDIF

oGen := CreateObject("Chilkat.XmlDSigGen")

//  Indicate the location within the XML the Signature will be inserted.
oGen:SigLocation := "abc|xyz"

//  Get the content of the text data to be referenced.
oHttp := CreateObject("Chilkat.Http")
oSbExternalTxt := CreateObject("Chilkat.StringBuilder")
nSuccess := oHttp:QuickGetSb("https://www.chilkatsoft.com/helloWorld.txt", oSbExternalTxt)
IF (nSuccess == 0)
    ? oHttp:LastErrorText
    oXml:destroy()
    oCert:destroy()
    oGen:destroy()
    oHttp:destroy()
    oSbExternalTxt:destroy()
    RETURN
ENDIF

nSuccess := oGen:AddExternalTextRef("https://www.chilkatsoft.com/helloWorld.txt", oSbExternalTxt, "utf-8", 0, "sha256", "")
IF (nSuccess == 0)
    ? oGen:LastErrorText
    oXml:destroy()
    oCert:destroy()
    oGen:destroy()
    oHttp:destroy()
    oSbExternalTxt:destroy()
    RETURN
ENDIF

//  Provide the private key for signing via the certificate, and indicate that
//  we want the base64 of the certificate embedded in the KeyInfo.
oGen:KeyInfoType := "X509Data"
oGen:X509Type := "Certificate"

nBUsePrivateKey := 1
nSuccess := oGen:SetX509Cert(oCert, nBUsePrivateKey)
IF (nSuccess != 1)
    ? oGen:LastErrorText
    oXml:destroy()
    oCert:destroy()
    oGen:destroy()
    oHttp:destroy()
    oSbExternalTxt:destroy()
    RETURN
ENDIF

//  Indicate we want an indented signature for readability.
//  This can be removed after debugging is finished..
oGen:Behaviors := "IndentedSignature"

//  Now create and insert the Signature
oSbXml := CreateObject("Chilkat.StringBuilder")
oXml:GetXmlSb(oSbXml)
nSuccess := oGen:CreateXmlDSigSb(oSbXml)
IF (nSuccess != 1)
    ? oGen:LastErrorText
    oXml:destroy()
    oCert:destroy()
    oGen:destroy()
    oHttp:destroy()
    oSbExternalTxt:destroy()
    oSbXml:destroy()
    RETURN
ENDIF

//  Examine the XML with the digital signature inserted
? oSbXml:GetAsString()

//  Here is the output:

//  <?xml version="1.0" encoding="utf-8"?>
//  <abc>
//      <xyz>
//          <name>helloWorld.txt</name>
//          <url>https://www.chilkatsoft.com/helloWorld.txt</url>
//      <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#"/>
//      <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
//      <ds:Reference URI="https://www.chilkatsoft.com/helloWorld.txt">
//        <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
//        <ds:DigestValue>f4OxZX/x/FO5LcGBSKHWXfwtSx+j1ncoSt3SABJtkGk=</ds:DigestValue>
//      </ds:Reference>
//    </ds:SignedInfo>
//    <ds:SignatureValue>syFSl...pZDiFQ==</ds:SignatureValue>
//    <ds:KeyInfo>
//      <ds:X509Data>
//        <ds:X509Certificate>MIIHAz...GwnUZWCaDE=</ds:X509Certificate>
//      </ds:X509Data>
//    </ds:KeyInfo>
//  </ds:Signature></xyz>
//  </abc>

//  Let's verify the signature...
oVerifier := CreateObject("Chilkat.XmlDSig")
nSuccess := oVerifier:LoadSignatureSb(oSbXml)
IF (nSuccess != 1)
    ? oVerifier:LastErrorText
    oXml:destroy()
    oCert:destroy()
    oGen:destroy()
    oHttp:destroy()
    oSbExternalTxt:destroy()
    oSbXml:destroy()
    oVerifier:destroy()
    RETURN
ENDIF

//  Let's examine the external references, and fetch the data for each..
oSbExternalData := CreateObject("Chilkat.StringBuilder")
nNumRefs := oVerifier:NumReferences
i := 0
DO WHILE i < nNumRefs
    nBExternal := oVerifier:IsReferenceExternal(i)
    IF (nBExternal == 1)
        cUri := oVerifier:ReferenceUri(i)

        //  We're assuming the URI is an https:// or http:// URL...
        //  Let's also assume we know that the referenced data is text and we want the utf-8 byte representation.
        oSbExternalData:Clear()
        nSuccess := oHttp:QuickGetSb(cUri, oSbExternalData)
        IF (nSuccess == 0)
            ? oHttp:LastErrorText
            oXml:destroy()
            oCert:destroy()
            oGen:destroy()
            oHttp:destroy()
            oSbExternalTxt:destroy()
            oSbXml:destroy()
            oVerifier:destroy()
            oSbExternalData:destroy()
            RETURN
        ENDIF

        nSuccess := oVerifier:SetRefDataSb(i, oSbExternalData, "utf-8")
        IF (nSuccess == 0)
            ? oVerifier:LastErrorText
            oXml:destroy()
            oCert:destroy()
            oGen:destroy()
            oHttp:destroy()
            oSbExternalTxt:destroy()
            oSbXml:destroy()
            oVerifier:destroy()
            oSbExternalData:destroy()
            RETURN
        ENDIF

    ENDIF

    i := i + 1
ENDDO

//  Now that we have the external data available, we can verify the reference digest(s) and the signature.
nBVerified := oVerifier:VerifySignature(1)
IF (nBVerified != 1)
    ? oVerifier:LastErrorText
    oXml:destroy()
    oCert:destroy()
    oGen:destroy()
    oHttp:destroy()
    oSbExternalTxt:destroy()
    oSbXml:destroy()
    oVerifier:destroy()
    oSbExternalData:destroy()
    RETURN
ENDIF

? "Signature verified!"

oXml:destroy()
oCert:destroy()
oGen:destroy()
oHttp:destroy()
oSbExternalTxt:destroy()
oSbXml:destroy()
oVerifier:destroy()
oSbExternalData:destroy()