PowerShell script for Entra ID app registration

Use this PowerShell script to generate a certificate and private key to use to connect your Entra ID app registration to Keepit.

After you download the script and before you run it, rename the file extension to .ps1.

Supported formats: 

• The certificate can have the following formats: CRT, CER, PEM. 
• The private key must be in the KEY format.

<#
.SYNOPSIS
    .
.DESCRIPTION
    Create Self-signed certificate with private and public keys.  
.PARAMETER PubKeyFileName
    Public key file name
.PARAMETER PrivKeyFileName
    Private key file name
.PARAMETER CertFileName
    Certificate file name with extention (.cer/.pem/.crt)

.EXAMPLE
    C:\PS> 
    generate-self-signed-cert.ps1 -PubKeyFileName <public key filename> -PrivKeyFileName <private key filename> -CertFileName <sertificate file name>.crt
#>
param (
 [Parameter(Mandatory=$true)][string]$PubKeyFileName = $( Read-Host "Enter public key file name: " ),
 [Parameter(Mandatory=$true)][string]$PrivKeyFileName = $( Read-Host "Enter private key file name: " ),
 [Parameter(Mandatory=$true)][string]$CertFileName = $( Read-Host "Enter certificate file name with extention (.cer/.pem/.crt): " )
)

#check for certificate extention
$ext = [IO.Path]::GetExtension($CertFileName)
if($ext -ne ".cer" -and $ext -ne ".pem" -and $ext -ne ".crt")
{
   Write-Output "You should enter certificate file name with extention (.cer/.pem/.crt). Run script again"
  Exit
}

$countryName = Read-Host -Prompt "Country Name (2 letter code) [AU]"
$provinceName = Read-Host -Prompt "State or province name (full name) [Some-State]"
$localityName = Read-Host -Prompt "Locality Name (eg, city)"
$organizationName = Read-Host -Prompt "Organization Name (eg, company) [Internet Widgits Pty Ltd]"
$organizationUnitName = Read-Host -Prompt "Organization Unit Name (eg, section) [Engineering]"
$commonName = Read-Host -Prompt "Common Name (e.g. server FQDN or YOUR name) [foo.org]"
$email = Read-Host -Prompt "Email address [foo@bar.baz]"

$currentDir = split-path -parent $MyInvocation.MyCommand.Definition;
Write-Output "Generating self-signed sertificate..."

$cert = New-SelfSignedCertificate -Subject "CN=$commonName,C=$countryName,ST=$provinceName,L=$localityName,O=$organizationName,OU=$organizationUnitName,emailAddress=$email" -CertStoreLocation "$currentDir" -NotAfter (Get-Date).AddYears(2) -KeyExportPolicy Exportable -KeySpec Signature -KeyLength 2048 -KeyAlgorithm RSA -HashAlgorithm SHA256
$binaryFile = New-TemporaryFile
Export-Certificate -Cert $cert -FilePath $binaryFile | Out-Null
# Certificate to Base64
$binaryContent = [System.IO.File]::ReadAllBytes($binaryFile)
$textContent = [System.Convert]::ToBase64String($binaryContent, [System.Base64FormattingOptions]::InsertLineBreaks)
# Certificate file contents
$textContentFormated = @"
-----BEGIN CERTIFICATE-----
$textContent
-----END CERTIFICATE-----
"@
# Output to file
[System.IO.File]::WriteAllLines("$currentDir/$CertFileName", $textContentFormated)



# Private key to Base64
$privateKey = [System.Security.Cryptography.X509Certificates.RSACertificateExtensions]::GetRSAPrivateKey($cert)
$privateKeyBytes = $privateKey.Key.Export([System.Security.Cryptography.CngKeyBlobFormat]::Pkcs8PrivateBlob)
$privateKeyBase64 = [System.Convert]::ToBase64String($privateKeyBytes, [System.Base64FormattingOptions]::InsertLineBreaks)
# Private key file contents
$privateKeyFileContent = @"
-----BEGIN PRIVATE KEY-----
$privateKeyBase64
-----END PRIVATE KEY-----
"@
# Output to file
[System.IO.File]::WriteAllLines("$currentDir/$PrivKeyFileName.key", $privateKeyFileContent)



# Public key to Base64
$publicKey = [System.Security.Cryptography.X509Certificates.RSACertificateExtensions]::GetRSAPublicKey($cert)
$publicKeyBytes = $privateKey.Key.Export([System.Security.Cryptography.CngKeyBlobFormat]::Pkcs8PrivateBlob)
$publicKeyBase64 = [System.Convert]::ToBase64String($publicKeyBytes, [System.Base64FormattingOptions]::InsertLineBreaks)
# Public key file contents
$publicKeyFileContent = @"
-----BEGIN PUBLIC KEY-----
$publicKeyBase64
-----END PUBLIC KEY-----
"@
# Output to file
[System.IO.File]::WriteAllLines("$currentDir/$PubKeyFileName.key", $publicKeyFileContent)

Write-Output "Public/Private key pair and a self-signed certificate generated successfully!"