RSA Signature/Verify with .key and .cer

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature.

Download 32-bit Chilkat RSA ActiveX (.msi)

Download All 32-bit Chilkat ActiveX Components (.zip)

Download All 64-bit Chilkat ActiveX Components (.zip)

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
Set outFile = fso.CreateTextFile("output.txt", True)

set privKey = CreateObject("Chilkat.PrivateKey")

'  Load the private key from an RSA .key file:
success = privKey.LoadPemFile("privateKey.key")
If (success <> 1) Then
    MsgBox privKey.LastErrorText
    WScript.Quit
End If

'  Get the private key in XML format:
privKeyXml = privKey.GetXml()

set rsa = CreateObject("Chilkat.Rsa")

'  Any string argument automatically begins the 30-day trial.
success = rsa.UnlockComponent("30-day trial")
If (success <> 1) Then
    MsgBox rsa.LastErrorText
    WScript.Quit
End If

'  Import the private key into the RSA component:
success = rsa.ImportPrivateKey(privKeyXml)
If (success <> 1) Then
    MsgBox rsa.LastErrorText
    WScript.Quit
End If

'  Create the signature as a hex string:
rsa.EncodingMode = "hex"

'  If some other non-Chilkat application or web service is going to be verifying
'  the signature, it is important to match the byte-ordering.
'  The LittleEndian property may be set to 1
'  for little-endian byte ordering,
'  or 0  for big-endian byte ordering.
'  Microsoft apps typically use little-endian, while
'  OpenSSL and other services (such as Amazon CloudFront)
'  use big-endian.
rsa.LittleEndian = 0

strData = "This is the string to be signed."

'  Sign the string using the sha-1 hash algorithm.
'  Other valid choices are "md2", "sha256", "sha384",
'  "sha512", and "md5".
hexSig = rsa.SignStringENC(strData,"sha-1")

outFile.WriteLine(hexSig)

'  Load a digital certificate from a .cer file:
set cert = CreateObject("Chilkat.Cert")

success = cert.LoadFromFile("myCert.cer")
If (success <> 1) Then
    MsgBox cert.LastErrorText
    WScript.Quit
End If

' pubKey is a Chilkat.PublicKey
Set pubKey = cert.ExportPublicKey()

'  Now verify using a separate instance of the RSA object:
set rsa2 = CreateObject("Chilkat.Rsa")

'  Import the public key into the RSA object:
success = rsa2.ImportPublicKey(pubKey.GetXml())
If (success <> 1) Then
    MsgBox rsa2.LastErrorText
    WScript.Quit
End If

'  The signature is a hex string, so make sure the EncodingMode is correct:
rsa2.EncodingMode = "hex"

'  Verify the signature:
success = rsa2.VerifyStringENC(strData,"sha-1",hexSig)
If (success <> 1) Then
    MsgBox rsa2.LastErrorText
    WScript.Quit
End If

MsgBox "Success."
outFile.Close