(Visual Basic 6.0) RSA Sign String using Private Key of Certificate Type A3 (smart card / token)

Demonstrates RSA signing a string using the private key of a certificate type A3 (smart card, token).

Note: This is a Windows-only example.

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

' First get the A3 certificate that was installed on the Windows system.
Dim certStore As New ChilkatCertStore

Dim thumbprint As String
thumbprint = "12c1dd8015f3f03f7b1fa619dc24e2493ca8b4b2"

' This is specific to Windows because it is opening the Windows Current-User certificate store.
Dim bReadOnly As Long
bReadOnly = 1
Dim success As Long
success = certStore.OpenCurrentUserStore(bReadOnly)
If (success <> 1) Then
    Debug.Print certStore.LastErrorText
    Exit Sub
End If

' Find the certificate with the desired thumbprint
' (There are many ways to locate a certificate.  This example chooses to find by thumbprint.)
Dim cert As ChilkatCert
Set cert = certStore.FindCertBySha1Thumbprint(thumbprint)
If (certStore.LastMethodSuccess <> 1) Then
    Debug.Print "Failed to find the certificate."
    Exit Sub
End If

Debug.Print "Found: " & cert.SubjectCN

Dim rsa As New ChilkatRsa

' Provide the cert's private key
Dim bUsePrivateKey As Long
bUsePrivateKey = 1
success = rsa.SetX509Cert(cert,bUsePrivateKey)

If (success <> 1) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

' Return the RSA signature in base64 encoded form.
rsa.EncodingMode = "base64"

' Sign the utf-8 byte representation of the string.
rsa.Charset = "utf-8"

' You can also choose other hash algorithms, such as SHA-1.
Dim sigBase64 As String
sigBase64 = rsa.SignStringENC("text to sign","SHA-256")
If (rsa.LastMethodSuccess <> 1) Then
    Debug.Print rsa.LastErrorText
    Exit Sub
End If

Debug.Print "Base64 signature: " & sigBase64