(VBScript) Get Public Key from CSR

Demonstrates how to get the public key from a CSR.

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)

' This requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Pem")
set pem = CreateObject("Chilkat.Pem")

' No password is required.  Pass an empty password string..
noPassword = ""
success = pem.LoadPemFile("qa_data/csr/csr2.pem",noPassword)
If (success <> 1) Then
    outFile.WriteLine(pem.LastErrorText)
    WScript.Quit
End If

strBase64 = pem.GetEncodedItem("csr","","base64",0)

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Asn")
set asn = CreateObject("Chilkat.Asn")
success = asn.LoadEncoded(strBase64,"base64")
If (success <> 1) Then
    outFile.WriteLine(asn.LastErrorText)
    WScript.Quit
End If

' Convert the ASN.1 to XML.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Xml")
set xml = CreateObject("Chilkat.Xml")
success = xml.LoadXml(asn.AsnToXml())
outFile.WriteLine(xml.GetXml())
outFile.WriteLine("----")

strModulusHex = xml.GetChildContent("bits")
outFile.WriteLine("strModulusHex = " & strModulusHex)
outFile.WriteLine("----")

' We need the modulus as base64.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.BinData")
set bd = CreateObject("Chilkat.BinData")
success = bd.AppendEncoded(strModulusHex,"hex")
modulus64 = bd.GetEncoded("base64")
outFile.WriteLine("modulus64 = " & modulus64)
outFile.WriteLine("----")

' Build the XML for the public key.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Xml")
set xmlPubKey = CreateObject("Chilkat.Xml")
xmlPubKey.Tag = "RSAPublicKey"
xmlPubKey.UpdateChildContent "Modulus",modulus64
' The RSA exponent will always be decimal 65537 (base64 = AQAB)
xmlPubKey.UpdateChildContent "Exponent","AQAB"

outFile.WriteLine("RSA public key as XML:")
outFile.WriteLine(xmlPubKey.GetXml())
outFile.WriteLine("----")

' Load the XML into a Chilkat public key object.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PublicKey")
set pubkey = CreateObject("Chilkat.PublicKey")
success = pubkey.LoadFromString(xmlPubKey.GetXml())
If (success <> 1) Then
    outFile.WriteLine(pubkey.LastErrorText)
    WScript.Quit
End If

' Show the public key as PEM.
preferPkcs1 = 1
outFile.WriteLine(pubkey.GetPem(preferPkcs1))

outFile.Close