VBScript

About RSA Public/Private Keys

See more RSA Examples

This example provides some additional information for understanding public/private key pairs. In demonstrates how a private key is a superset of the public key. A public key contains the modulus and exponent. The matching private key also contains the modulus and exponent, but also contains the additional private key parts. VBScript

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

success = 0

set cert = CreateObject("Chilkat.Cert")

' Load a digital certificate.
success = cert.LoadFromFile("digitalCert.cer")
If (success = 0) Then
    outFile.WriteLine(cert.LastErrorText)
    WScript.Quit
End If

' A .cer file does not contain the private key.  It should contain
' the public key...
set pubKey = CreateObject("Chilkat.PublicKey")
success = cert.GetPublicKey(pubKey)

' Let's have a look at it (in XML format).
outFile.WriteLine("Public Key from Certificate:")
outFile.WriteLine(pubKey.GetXml())

' An RSA public key consists of a modulus and exponent.

' An RSA private key includes both the modulus and exponent,
' as well as other "big" numbers: P, Q, D, etc.

' Let's load an RSA private key from a DER-encoded file:
set privKey = CreateObject("Chilkat.PrivateKey")

success = privKey.LoadAnyFormatFile("PrivateKey.key","")
If (success <> 1) Then
    outFile.WriteLine(privKey.LastErrorText)
    WScript.Quit
End If

' If this private key is the matching half to the public key from
' the certificate, then the modulus and exponent should
' be identical.  (Thus, a "private key" really contains both the public part as well as the private parts...).
outFile.WriteLine("Private Key from DER:")
outFile.WriteLine(privKey.GetXml())

outFile.Close