A PowerShell script to mass export client certificates from a server

Export-ClientCertificates.ps1

param(
    [Parameter(Mandatory = $true)]
    [String[]]$Thumbprints,
    [Parameter(Mandatory = $true)]
    [String]$Password
    )
#### Usage ####
# .\Export-ClientCertificates.ps1 -Thumbprints "array","of","thumbprints","and","subject","common","names" -Password "PrivateKeyPassword"
####
    
$passwd = ConvertTo-SecureString -String $Password -Force -AsPlainText

$certPath = "Cert:\LocalMachine\My"


ForEach ($certprint in $Thumbprints) {
    $cert = Get-ChildItem $certPath -Recurse | ? { $_ -is [System.Security.Cryptography.X509Certificates.X509Certificate2] } | ? {$_.Thumbprint -eq $certprint.Replace(" ","").ToUpper()}

    if ($cert -eq $null) {        
        $cert = Get-ChildItem $certPath -Recurse | ? { $_ -is [System.Security.Cryptography.X509Certificates.X509Certificate2] } | ? {$_.SubjectName.Name.ToUpper() -like "*CN=$certprint,*".ToUpper()}
        }

    if (-Not ($cert -eq $null)) {
        $certSubjectName = $cert.SubjectName.Name
        #Write-Host "Found Subject Name: $certSubjectName"

        if ($cert.SubjectName.Name -match "CN=(?<commonName>[^,]*)") {
            
            $certCommonName = $Matches['commonName']
            #Write-Host "Found Common Name: $certCommonName"
            
            $certThumbprint = $cert.Thumbprint
            #Write-Host "Found Thumbprint: $certThumbprint"
            
            $exportFile = "$certCommonName ($certThumbprint).pfx"
            #Write-Host "Writing to $exportFile"

            $cert | Export-PfxCertificate -FilePath $exportFile -Password $passwd -ChainOption BuildChain
            }
        }
}