(PowerShell) Convert RSA Private Key to Public Key

Demonstrates how to get a public RSA key from a private RSA key.

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

$key = New-Object Chilkat.PrivateKey

# Step 1: Load the private key from a source.
# (Chilkat can load private keys from all types of formats, and from in-memory bytes or encoded strings.
# see the online reference documentation for more options.)
$success = $key.LoadPemFile("qa_data/pem/VP_Private.pem")
if ($success -ne $true) {
    $($key.LastErrorText)
    exit
}

# Step 2: Get the public key object from the private key object.
$pubKey = $key.GetPublicKey()
if ($key.LastMethodSuccess -ne $true) {
    $($key.LastErrorText)
    exit
}

# Step 3: Save the public key in a desired format. 
# (Chilkat can load or save public and private keys in many different formats.  See
# the online reference documentation for more options.)

# Saves to a PKCS8 PEM file.
$bPreferPkcs1 = $false
$success = $pubKey.SavePemFile($bPreferPkcs1,"qa_data/pem/VP_Public.pem")
if ($pubKey.LastMethodSuccess -ne $true) {
    $($pubKey.LastErrorText)
    exit
}

$("Extracted and saved public key from private key.")