(PowerShell) Trust Specific Root CA Certificates

Demonstrates how to trust specific root CA certificates and none others.

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

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

# This example will trust the Amazon root CA certificates provided at 
# https://www.amazontrust.com/repository/

# I've previously downloaded the root CA certificates to DER format.
# Add each to the Chilkat TrustedRoots singleton object.

$tRoots = New-Object Chilkat.TrustedRoots

$caCert = New-Object Chilkat.Cert
$success = $caCert.LoadFromFile("qa_data/certs/aws_root_ca/AmazonRootCA1.cer")
if ($success -eq $false) {
    $($caCert.LastErrorText)
    exit
}

$success = $tRoots.AddCert($caCert)

# Continue with the others.
# For brevity, we're not checking return values for success/failure.
$success = $caCert.LoadFromFile("qa_data/certs/aws_root_ca/AmazonRootCA2.cer")
$success = $tRoots.AddCert($caCert)

$success = $caCert.LoadFromFile("qa_data/certs/aws_root_ca/AmazonRootCA3.cer")
$success = $tRoots.AddCert($caCert)

$success = $caCert.LoadFromFile("qa_data/certs/aws_root_ca/AmazonRootCA4.cer")
$success = $tRoots.AddCert($caCert)

$success = $caCert.LoadFromFile("qa_data/certs/aws_root_ca/SFSRootCAG2.cer")
$success = $tRoots.AddCert($caCert)

# Indicate we don't want to automatically trust the operating system's installed root CA certificates.
# On a Windows operating system, this would be the registry-based CA certificate stores. 
# On a Linux system, this could be /etc/ssl/certs/ca-certificates.crt, if it exists.
$tRoots.TrustSystemCaRoots = $false

# Activate the trusted roots object.
# Once activated, all Chilkat objects that use TLS connections (HTTP, REST, Socket, MailMan, IMAP, FTP, etc.)
# will fail the TLS handshake if the server certificate is not verified and rooted with one of our explicitly trusted root certificates.
$success = $tRoots.Activate()

$http = New-Object Chilkat.Http

# Note: We also need to explicitly indicate that server certificates are to be verified.
$http.RequireSslCertVerify = $true

# For example, the following should fail because www.chilkatsoft.com's server certificate is not rooted in one of the explicitly trusted root CA certs.
$success = $http.Download("https://www.chilkatsoft.com/helloWorld.txt","qa_output/helloWorld.txt")
if ($success -ne $true) {
    # The above Download should fail.
    $($http.LastErrorText)

    # There should be a message in the LastErrorText indicating that we were "Unable to build certificate chain to root.."
}

# However, we should be able to make TLS connections to good.sca1a.amazontrust.com
$success = $http.Download("https://good.sca1a.amazontrust.com/","qa_output/valid.html")
if ($success -ne $true) {
    $($http.LastErrorText)
    exit
}

# We can still examine the LastErrorText and we'll find this message within:  
# "The public key was successfully validated against the public key of the explicitly trusted root cert."
$($http.LastErrorText)

$("Success!")