(VB.NET) 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.

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

Dim thumbprint As String = "12c1dd8015f3f03f7b1fa619dc24e2493ca8b4b2"

' This is specific to Windows because it is opening the Windows Current-User certificate store.
Dim bReadOnly As Boolean = True
Dim success As Boolean = certStore.OpenCurrentUserStore(bReadOnly)
If (success <> True) Then
    Debug.WriteLine(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 Chilkat.Cert = certStore.FindCertBySha1Thumbprint(thumbprint)
If (certStore.LastMethodSuccess <> True) Then
    Debug.WriteLine("Failed to find the certificate.")
    Exit Sub
End If


Debug.WriteLine("Found: " & cert.SubjectCN)


Dim rsa As New Chilkat.Rsa

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

If (success <> True) Then
    Debug.WriteLine(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 = rsa.SignStringENC("text to sign","SHA-256")
If (rsa.LastMethodSuccess <> True) Then
    Debug.WriteLine(rsa.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("Base64 signature: " & sigBase64)