v1 PowerShell Script to validate YubiKey using Single Factor. Associated Blogpost https://blog.darrenjrobinson.com/validating-a-yubico-yubikeys-one-time-password-otp-using-single-factor-authentication-and-powershell/

ValidateYubiKey-SingleFactor.ps1

# Client ID obtained after registering here https://upgrade.yubico.com/getapikey/
$clientID = '12345'
# Read in the key
$getKey = Read-Host 'Insert your YubiKey and touch it until the OTP is received (~2 seconds)'
$credentialID = $getKey.Substring(0,12)
# Generate a Nonce
$nonce = -join ((65..90) + (97..122) | Get-Random -Count 32 | % {[char]$_})
$nonce = $nonce.ToLower()
# Build the URI
$uri = "http://api.yubico.com/wsapi/2.0/verify?id=$($clientID)&nonce=$($nonce)&otp=$($getKey)"
# Invoke Web Request
$response = Invoke-WebRequest -Method GET -Uri $uri
# Split the response into an array
$lines = $response.ParsedHtml.body.innerText -split " "  

# Check to the response and output
if ($response.ParsedHtml.body.innerText.Contains("status=OK")){
    # SUCCESSFUL
    write-host "***********SUCCESS****************" 
    write-host "Credential ID $($credentialID)"
    $i=0 
    foreach ($line in $lines){
        $linenumber = $i
        switch ($linenumber) {
            0 {write-host "Signature $($line)"}
            1 {write-host "Time $($line)"}
            2 {write-host "$($line)"}
            3 {write-host "$($line)"}
            4 {write-host "% $($line)"}
            5 {write-host "$($line)"}
        } 
        $i++   
    }
} else {
    $i=0
    # ERROR
    write-host "============ERROR===============" 
    write-host "Credential ID $($credentialID)"
    foreach ($line in $lines){
        $linenumber = $i
        switch ($linenumber) {
            4 {write-host "$($line)"}
            5 {write-host "$($line)"}
        } 
        $i++   
    }   
}