(VBScript) Convert RSA Private Key to Public Key

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

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PrivateKey")
set key = CreateObject("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 <> 1) Then
    outFile.WriteLine(key.LastErrorText)
    WScript.Quit
End If

' Step 2: Get the public key object from the private key object.
' pubKey is a Chilkat.PublicKey
Set pubKey = key.GetPublicKey()
If (key.LastMethodSuccess <> 1) Then
    outFile.WriteLine(key.LastErrorText)
    WScript.Quit
End If

' 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 = 0
success = pubKey.SavePemFile(bPreferPkcs1,"qa_data/pem/VP_Public.pem")
If (pubKey.LastMethodSuccess <> 1) Then
    outFile.WriteLine(pubKey.LastErrorText)
    WScript.Quit
End If

outFile.WriteLine("Extracted and saved public key from private key.")

outFile.Close