(Classic ASP) 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

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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
' 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.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Xml")
set xml = Server.CreateObject("Chilkat.Xml")
xml.Tag = "abc"
xml.UpdateChildContent "xyz|name","helloWorld.txt"
xml.UpdateChildContent "xyz|url","https://www.chilkatsoft.com/helloWorld.txt"

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Cert")
set cert = Server.CreateObject("Chilkat.Cert")

success = cert.LoadPfxFile("qa_data/pfx/test_secret.pfx","secret")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( cert.LastErrorText) & "</pre>"
    Response.End
End If

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.XmlDSigGen")
set gen = Server.CreateObject("Chilkat.XmlDSigGen")

' Indicate the location within the XML the Signature will be inserted.
gen.SigLocation = "abc|xyz"

' Get the content of the text data to be referenced.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Http")
set http = Server.CreateObject("Chilkat.Http")
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbExternalTxt = Server.CreateObject("Chilkat.StringBuilder")
success = http.QuickGetSb("https://www.chilkatsoft.com/helloWorld.txt",sbExternalTxt)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( http.LastErrorText) & "</pre>"
    Response.End
End If

success = gen.AddExternalTextRef("https://www.chilkatsoft.com/helloWorld.txt",sbExternalTxt,"utf-8",0,"sha256","")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( gen.LastErrorText) & "</pre>"
    Response.End
End If

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

bUsePrivateKey = 1
success = gen.SetX509Cert(cert,bUsePrivateKey)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( gen.LastErrorText) & "</pre>"
    Response.End
End If

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

' Now create and insert the Signature
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbXml = Server.CreateObject("Chilkat.StringBuilder")
success = xml.GetXmlSb(sbXml)
success = gen.CreateXmlDSigSb(sbXml)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( gen.LastErrorText) & "</pre>"
    Response.End
End If

' Examine the XML with the digital signature inserted
Response.Write "<pre>" & Server.HTMLEncode( sbXml.GetAsString()) & "</pre>"

' 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...
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.XmlDSig")
set verifier = Server.CreateObject("Chilkat.XmlDSig")
success = verifier.LoadSignatureSb(sbXml)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( verifier.LastErrorText) & "</pre>"
    Response.End
End If

' Let's examine the external references, and fetch the data for each..
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbExternalData = Server.CreateObject("Chilkat.StringBuilder")
numRefs = verifier.NumReferences
i = 0
Do While i < numRefs
    bExternal = verifier.IsReferenceExternal(i)
    If (bExternal = 1) Then
        uri = verifier.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.
        sbExternalData.Clear 
        success = http.QuickGetSb(uri,sbExternalData)
        If (success = 0) Then
            Response.Write "<pre>" & Server.HTMLEncode( http.LastErrorText) & "</pre>"
            Response.End
        End If

        success = verifier.SetRefDataSb(i,sbExternalData,"utf-8")
        If (success = 0) Then
            Response.Write "<pre>" & Server.HTMLEncode( verifier.LastErrorText) & "</pre>"
            Response.End
        End If

    End If

    i = i + 1
Loop

' Now that we have the external data available, we can verify the reference digest(s) and the signature.
bVerified = verifier.VerifySignature(1)
If (bVerified <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( verifier.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "Signature verified!") & "</pre>"

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