(Visual Basic 6.0) How to Parse a X.509 Certificate and Extract its Public Key

Demonstrates how to load an X.509 certificate and extract the public key. Chilkat supports many certificate encodings:

• DER (binary) encoded certificates (.crt/.cer)
• PEM (BASE64) encoded certificates (.pem)
• Load Certificates Directly from Windows Certificate Stores
• PFX/PKCS12 (.pfx/.p12)
• Java KeyStore (.jks)
• Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B)

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

Dim cert As New ChilkatCert

' Load a DER (binary) encoded certificate.
' To load from a .pem or .p7b, or any other file format that contains
' just one certificate, call LoadFromFile in exactly the same way.
' The LoadFromFile method automatically detects the format and loads the certificate.
Dim success As Long
success = cert.LoadFromFile("qa_data/certs/testCert.cer")
If (success = 0) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

' Get the public key:
Dim pubKey As PublicKey
Set pubKey = cert.ExportPublicKey()
If (cert.LastMethodSuccess <> 1) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

' Examine the key type.
' A PublicKey object can contain an RSA, ECC, or DSA public key.
' The KeyType property will contain "rsa", "ecc", or "dsa".
Debug.Print "key type = " & pubKey.KeyType