(Excel) HTTP - Verify Server is a Trusted Root CA

Demonstrates how to only allow connections to an HTTP server having a certificate with a root that is in our list of trusted CA root certificates.

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' Starting in v9.5.0.49, all Chilkat classes can be unlocked at once at the beginning of a program
' by calling UnlockBundle.  It requires a Bundle unlock code.
Dim chilkatGlob As Chilkat.CkGlobal
Set chilkatGlob = Chilkat.NewCkGlobal

success = chilkatGlob.UnlockBundle("Anything for 30-day trial.")
If (success <> True) Then
    Debug.Print chilkatGlob.LastErrorText
    Exit Sub
End If

'  On my particular system, the root CA cert for this URL is not pre-installed.
'  Note: This may be different for you.
'  Also, this example was written on 29-May-2015.  This URL was valid at the time,
'  but may not be valid at a future date.

url = "https://animals.nationalgeographic.com/animals/invertebrates/starfish/"

Dim http As Chilkat.Http
Set http = Chilkat.NewHttp

'  Require that the SSL/TLS server certificate is not expired,
'  and that the certificate signature is valid.
'  This does not ensure that it has a chain of authentication to
'  a trusted root.  To ensure that, the TrustedRoots object (below) is required.
http.RequireSslCertVerify = True

'  Do the HTTPS page fetch (through the SSH tunnel)

html = http.QuickGetStr(url)
If (http.LastMethodSuccess <> True) Then
    Debug.Print http.LastErrorText
    Exit Sub
End If

Debug.Print "The HTTP GET was successful."

'  Now let's require that HTTP requests to SSL/TLS servers that don't have trusted CA roots
'  should fail.
Dim trustedRoots As Chilkat.TrustedRoots
Set trustedRoots = Chilkat.NewTrustedRoots

'  Indicate that we will trust any pre-installed certificates on this system.
'  (The meaning of pre-installed certificates depends on the operating system, and in
'  some environments there is no such thing as pre-installed certificates.  See the reference
'  documentation for the TrustedRoots class.)
trustedRoots.TrustSystemCaRoots = True

'  Activate the trusted roots globally for all Chilkat objects.
'  This call really shouldn't fail, so we're not checking the return value.
success = trustedRoots.Activate()

'  Given that our previous HTTP GET likely kept the connection open,
'  make sure that all HTTP connections are closed before re-trying.
'  Otherwise, we'll simply be re-using the pre-existing connection.
success = http.CloseAllConnections()

'  Now let's try fetching the URL again.  It should fail this time because
'  there is a requirement that the SSL/TLS server certificate must have a trusted root,
'  and the trusted root for this URL is not installed on my system (but may be different for you..)
html = http.QuickGetStr(url)
If (http.LastMethodSuccess <> True) Then
    Debug.Print http.LastErrorText
    Debug.Print "Good, the HTTP request failed as expected."
Else
    Debug.Print http.LastErrorText
    Debug.Print "Hmmm... we did not fail as expected?"
End If