Gets the thumbprint of a web site's HTTPS certificate

Get-WebSiteCertificateThumbprint.ps1

<#
.SYNOPSIS
Returns the SSL thumbprint for the certificate of the website

.DESCRIPTION 
The certificate's thumbprint is a hash of the certificate's properties and keys. It is, in theory, a globally unique identifier.

.OUTPUTS
System.String
Get-WebSiteCertificateThumbprint returns a string with the certificate's thumbprint.

.PARAMETER url
The URL to be tested. Can be a domain root or any URL underneath a domain. Must be HTTPS.

.EXAMPLE
Get-WebSiteCertificateThumbprint -url https://www.github.com/
D79F076110B39293E349AC89845B0380C19E2F8B

.LINK
https://github.com/chrisbrownie/

.NOTES

Copyright (c) 2016 Chris Brown

Permission is hereby granted, free of charge, to any person obtaining a copy 
of this software and associated documentation files (the "Software"), to deal 
in the Software without restriction, including without limitation the rights 
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
copies of the Software, and to permit persons to whom the Software is 
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all 
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
DEALINGS IN THE SOFTWARE.

#>
Param(
    [Parameter(Mandatory=$true)]
    [string]
    $url
    )
    
$request = [System.Net.WebRequest]::Create($url)

try {
    $request.GetResponse() | Out-Null
} catch {
    throw "Unable to connect to site '$url'!"
}
return $request.ServicePoint.Certificate.GetCertHashString()