PowerBuilder

Verify XML Digital Signature having KeyName

See more XML Digital Signatures Examples

Demonstrates how to verify an XML digital signature where the KeyInfo part contains the KeyName element.
In this case, the public key is not specifically stored in the signed XML.
Rather, application specific information about the key is stored in the KeyName element.
This example uses the KeyName to find and matching public key.

This example requires Chilkat v9.5.0.69 or greater.

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integer li_rc
integer li_Success
string ls_Url
oleobject loo_Http
oleobject loo_SbXml
oleobject loo_Verifier
oleobject loo_XmlKeyInfo
oleobject loo_SbKeyName
oleobject loo_PubKey
integer li_BVerified

li_Success = 0

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

// The signed XML to be verified in this example contains the following:
// 
// <?xml version="1.0" encoding="UTF-8" standalone="no"?>
// <Envelope>
//   <Header>
//     <Security>
//     <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/2009/xmldsig11#dsa-sha256"/><ds:Reference URI="#abc"><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>XTjDIHSEsDNTO9yn4cKtyXjRUjPFXkOQOLYI5mueZhk=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>NXOIMevGCqFl0Dwtp2KkqkT05GRV8CjmHZ9LhFpt8/d7+lkIi7mITA==</ds:SignatureValue><ds:KeyInfo><ds:KeyName>dsaKey_123</ds:KeyName></ds:KeyInfo></ds:Signature></Security>
//   </Header>
//   <Body Id="abc">
//     <z:FooBar xmlns:z="https://www.example-code.com"/>
//   </Body>
// </Envelope>
// 

// The above XML is available at https://www.chilkatsoft.com/exampleData/signedUsingKeyName.xml
// First we'll fetch the signed XML:

ls_Url = "https://www.chilkatsoft.com/exampleData/signedUsingKeyName.xml"
loo_Http = create oleobject
li_rc = loo_Http.ConnectToNewObject("Chilkat.Http")
if li_rc < 0 then
    destroy loo_Http
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_SbXml = create oleobject
li_rc = loo_SbXml.ConnectToNewObject("Chilkat.StringBuilder")

li_Success = loo_Http.QuickGetSb(ls_Url,loo_SbXml)
if li_Success <> 1 then
    Write-Debug loo_Http.LastErrorText
    destroy loo_Http
    destroy loo_SbXml
    return
end if

loo_Verifier = create oleobject
li_rc = loo_Verifier.ConnectToNewObject("Chilkat.XmlDSig")

// Load the XML containing the signature to be verified.
li_Success = loo_Verifier.LoadSignatureSb(loo_SbXml)
if li_Success <> 1 then
    Write-Debug loo_Verifier.LastErrorText
    destroy loo_Http
    destroy loo_SbXml
    destroy loo_Verifier
    return
end if

// (The Chilkat XML Digital Signature API has the capability to handle XML documents with multiple signatures.
// We know in advance that this signed XML has just one Signature, so we leave the dsig.Selector property at the
// default value of 0.)

// Let's get the KeyInfo XML so we can then get the KeyName.
loo_XmlKeyInfo = loo_Verifier.GetKeyInfo()
if loo_Verifier.LastMethodSuccess = 0 then
    Write-Debug "There is no KeyInfo available in the Signature."
    destroy loo_Http
    destroy loo_SbXml
    destroy loo_Verifier
    return
end if

// Examine the XML:
Write-Debug loo_XmlKeyInfo.GetXml()

// The KeyInfo XML that is returned looks like this:
// 
// 	<ds:KeyInfo>
// 	    <ds:KeyName>dsaKey_123</ds:KeyName>
// 	</ds:KeyInfo>
// 

// Get the KeyName.
loo_SbKeyName = create oleobject
li_rc = loo_SbKeyName.ConnectToNewObject("Chilkat.StringBuilder")

loo_SbKeyName.Append(loo_XmlKeyInfo.GetChildContent("*:KeyName"))
destroy loo_XmlKeyInfo

// sbKeyName contains "dsaKey_123"
Write-Debug loo_SbKeyName.GetAsString()

// The application now locates and loads the public key for verification
// based on the key name.  This example will do the following:
// If the key name equals "dsaKey_123", then load the DSA key from
// "qa_data/dsa/dsa1024_public.pem"
// 

if loo_SbKeyName.ContentsEqual("dsaKey_123",0) = 0 then
    Write-Debug "I don't know this key..."
    destroy loo_Http
    destroy loo_SbXml
    destroy loo_Verifier
    destroy loo_SbKeyName
    return
end if

// The DSA public key used in this example is available at:
// https://www.chilkatsoft.com/exampleData/dsa1024_public.zip
loo_PubKey = create oleobject
li_rc = loo_PubKey.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey.LoadFromFile("qa_data/dsa/dsa1024_public.pem")
if li_Success <> 1 then
    Write-Debug loo_PubKey.LastErrorText
    destroy loo_Http
    destroy loo_SbXml
    destroy loo_Verifier
    destroy loo_SbKeyName
    destroy loo_PubKey
    return
end if

// Provide the DSA public key to the XML DSig verifier:
loo_Verifier.SetPublicKey(loo_PubKey)

// Verify the signature
li_BVerified = loo_Verifier.VerifySignature(1)
Write-Debug "Signature verified = " + string(li_BVerified)


destroy loo_Http
destroy loo_SbXml
destroy loo_Verifier
destroy loo_SbKeyName
destroy loo_PubKey