(Visual Basic 6.0) Get Certificates from .p12 / .pfx

A PKCS12 (.p12 / .pfx) is a container for holding a certificate, its private key, and the certs in the chain of authentication up to and possibly including the root CA cert. A .p12 is not required to contain certain things. It will contain whatever the creator of the .p12 decided to include. It's possible to contain just a private key, just a cert, many certs without private keys, or many certs with many private keys. Usually, a .p12 contains one certificate, its associated private key, and certificates in the chain of authentication.

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

Dim pfx As New ChilkatPfx

Dim success As Long
success = pfx.LoadPfxFile("qa_data/pfx/test.pfx","pfx_password")
If (success = 0) Then
    Debug.Print pfx.LastErrorText
    Exit Sub
End If

' Iterate over the certs contained in the PFX
Dim numCerts As Long
numCerts = pfx.NumCerts
Dim i As Long
i = 0
Do While i < numCerts
    Dim cert As ChilkatCert
    Set cert = pfx.GetCert(i)

    Debug.Print "--- " & i & " ---"
    Debug.Print cert.SubjectDN
    ' Is this a root cert, or self-signed?
    Debug.Print "Root: " & cert.IsRoot
    Debug.Print "Self-Signed: " & cert.SelfSigned

    ' If this certificate is not the root (self-signed), then get the issuer.
    ' If the issuing certificate is contained in the PFX, then it will be found here..
    If (cert.SelfSigned <> 1) Then
        Dim issuer As ChilkatCert
        Set issuer = cert.FindIssuer()
        If (cert.LastMethodSuccess = 0) Then
            Debug.Print "Issuer not found."
        Else
            Debug.Print "Issuer: " & issuer.SubjectDN

        End If

    End If

    i = i + 1
Loop

' Usually, the user certificate is at index 0, its issuer is at index 1, etc. until we get to the root certificate.