Using PowerShell to Create Self-Signed Certificate

Question

I'm using code similar to that found here to create a self-signed certificate for use in IIS: http://blogs.technet.com/b/vishalagarwal/archive/2009/08/22/generating-a-certificate-self-signed-using-powershell-and-certenroll-interfaces.aspx

Works fine except I want to give it a friendly name to make locating it easier when I want to assign the certificate to a dynamically created site.

Anyone know how to change the above to set the friendly name (I've tried what seemed obvious to no avail).

Got a better way to create a cert via PowerShell that does not prompt the user for information?

Followup on the script I am using - based on the url above but turned into a cmdlet:

function Add-SelfSignedCertificate
{
    [CmdletBinding()]
    param
    (
            [Parameter(Mandatory=$True, ValueFromPipelineByPropertyName=$True)]
            [Alias('cn')]
            [string]$CommonName
    )

    $name = new-object -com "X509Enrollment.CX500DistinguishedName.1"
    $name.Encode("CN=$CommonName", 0)

    $key = new-object -com "X509Enrollment.CX509PrivateKey.1"
    $key.ProviderName = "Microsoft RSA SChannel Cryptographic Provider"
    $key.KeySpec = 1
    $key.Length = 1024
    $key.SecurityDescriptor = "D:PAI(A;;0xd01f01ff;;;SY)(A;;0xd01f01ff;;;BA)(A;;0x80120089;;;NS)"
    $key.MachineContext = 1
    $key.Create()

    $serverauthoid = new-object -com "X509Enrollment.CObjectId.1"
    $serverauthoid.InitializeFromValue("1.3.6.1.5.5.7.3.1")
    $ekuoids = new-object -com "X509Enrollment.CObjectIds.1"
    $ekuoids.add($serverauthoid)
    $ekuext = new-object -com "X509Enrollment.CX509ExtensionEnhancedKeyUsage.1"
    $ekuext.InitializeEncode($ekuoids)

    $cert = new-object -com "X509Enrollment.CX509CertificateRequestCertificate.1"
    $cert.InitializeFromPrivateKey(2, $key, "")
    $cert.Subject = $name
    $cert.Issuer = $cert.Subject
    $cert.NotBefore = get-date
    $cert.NotAfter = $cert.NotBefore.AddDays(90)
    $cert.X509Extensions.Add($ekuext)
    $cert.Encode()

    $enrollment = new-object -com "X509Enrollment.CX509Enrollment.1"
    $enrollment.InitializeFromRequest($cert)
    $certdata = $enrollment.CreateRequest(0)
    $enrollment.InstallResponse(2, $certdata, 0, "")
}

Answer 1

Scott Hanselman wrote up a nice blog post on how to create a self-signed cert using the SDK tool makecert.exe. That tool looks to be a good bit easer to use than the code in the post you reference. With makecert.exe you can use the -n option to specify a subject name. I've used that subject name to refer to the certificate in other tools like signtool.exe. Although, I've found that subject names don't have to be unique so I tend to use the Thumbprint value which appears to be unique. Signtool will also accept a thumbprint (via the /sha1 parameter) to identify the cert.

Answer 2

You can set the CertificateFriendlyName directly in you code, you just need to know where to do it:

$enrollment.InitializeFromRequest($cert)
$enrollment.CertificateFriendlyName = 'whatever'
$certdata = $enrollment.CreateRequest(0)

$key has a FriendlyName but I don't see that showing up anywhere so I don't think it helps you.

Answer 3

It might not help for your specific use, but there is a new Powershell CmdLet installed in Windows 8.1 and Server 2012 that is pretty quick and easy to use:

New-SelfSignedCertificate [-CertStoreLocation <String> ] [-CloneCert <Certificate> ] [-DnsName <String> ] [-Confirm] [-WhatIf] [ <CommonParameters>]

More details can be found here: https://docs.microsoft.com/en-us/powershell/module/pkiclient/new-selfsignedcertificate?view=win10-ps

In my usage, the friendly name of the cert has always been set as the first DnsName specified in the CmdLet.

Example that places the certificate in your Local Computer's Personal store:

New-SelfSignedCertificate -CertStoreLocation cert:\LocalMachine\My -DnsName www.example.com

Note: Powershell has to be started with admin rights for this to work.