Visual Basic 6.0

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. Visual Basic 6.0

Dim success As Long
success = 0

Dim cert As New ChilkatCert

' Load a digital certificate.
success = cert.LoadFromFile("digitalCert.cer")
If (success = 0) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

' A .cer file does not contain the private key.  It should contain
' the public key...
Dim pubKey As New PublicKey
success = cert.GetPublicKey(pubKey)

' Let's have a look at it (in XML format).
Debug.Print "Public Key from Certificate:"
Debug.Print 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:
Dim privKey As New PrivateKey

success = privKey.LoadAnyFormatFile("PrivateKey.key","")
If (success <> 1) Then
    Debug.Print privKey.LastErrorText
    Exit Sub
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...).
Debug.Print "Private Key from DER:"
Debug.Print privKey.GetXml()