(Visual Basic 6.0) 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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' 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..

Dim url As String
url = "https://www.chilkatsoft.com/exampleData/soapToSign.xml"
Dim http As New ChilkatHttp
Dim sbSoapXml As New ChilkatStringBuilder
Dim success As Long
success = http.QuickGetSb(url,sbSoapXml)
If (success <> 1) Then
    Debug.Print http.LastErrorText
    Exit Sub
End If

' 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
Dim ecKey As New PrivateKey
success = ecKey.LoadPemFile("qa_data/ecc/secp256r1-key.pem")
If (success <> 1) Then
    Debug.Print ecKey.LastErrorText
    Exit Sub
End If

' 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.
' 

Dim xmlSigGen As New ChilkatXmlDSigGen

' 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.
xmlSigGen.SigLocation = "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.
success = xmlSigGen.AddSameDocRef("Body","sha256","EXCL_C14N","","")

' Let's provide the ECDSA key to be used for signing:
success = xmlSigGen.SetPrivateKey(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.
xmlSigGen.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.
success = xmlSigGen.CreateXmlDSigSb(sbSoapXml)
If (success <> 1) Then
    Debug.Print xmlSigGen.LastErrorText
    Exit Sub
End If

' Examine the signed SOAP XML:
Debug.Print sbSoapXml.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#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:

Dim verifier As New ChilkatXmlDSig

' First load the XML containing the signature(s) to be verified.
success = verifier.LoadSignatureSb(sbSoapXml)
If (success <> 1) Then
    Debug.Print verifier.LastErrorText
    Exit Sub
End If

Dim bVerified As Long
bVerified = verifier.VerifySignature(1)
If (bVerified <> 1) Then
    Debug.Print verifier.LastErrorText
End If

Debug.Print "Signature verified = " & bVerified