Sign a File to Create a .p7s (Detached Signature)

VB.NET example to create a detached signature file (.p7s) for any type file. The signature can be verified by calling VerifyP7S and passing the original filename and the .p7s filename.

Download: Chilkat .NET Assemblies

Dim crypt As New Chilkat.Crypt2()

'  Any string argument automatically begins the 30-day trial.
Dim success As Boolean
success = crypt.UnlockComponent("30-day trial")
If (success <> true) Then
    TextBox1.Text = TextBox1.Text & crypt.LastErrorText & vbCrLf
    Exit Sub
End If


'  Use a digital certificate and private key from a PFX file (.pfx or .p12).
Dim signingCertSubject As String
signingCertSubject = "Acme Inc"
Dim pfxFilename As String
pfxFilename = "/Users/chilkat/testData/pfx/acme.pfx"
Dim pfxPassword As String
pfxPassword = "test123"

Dim certStore As New Chilkat.CertStore()
success = certStore.LoadPfxFile(pfxFilename,pfxPassword)
If (success <> true) Then
    TextBox1.Text = TextBox1.Text & certStore.LastErrorText & vbCrLf
    Exit Sub
End If


Dim cert As Chilkat.Cert
cert = certStore.FindCertBySubjectCN(signingCertSubject)
If (cert Is Nothing ) Then
    TextBox1.Text = TextBox1.Text & "Failed to find certificate by subject common name." & vbCrLf
    Exit Sub
End If


'  Tell the crypt component to use this cert.
crypt.SetSigningCert(cert)


'  We can sign any type of file, creating a .p7s as output:
Dim inFile As String
inFile = "/Users/chilkat/testData/pdf/sample.pdf"
Dim sigFile As String
sigFile = "/Users/chilkat/testData/p7s/sample.p7s"

success = crypt.CreateP7S(inFile,sigFile)
If (success = false) Then
    TextBox1.Text = TextBox1.Text & crypt.LastErrorText & vbCrLf

    Exit Sub
End If


success = crypt.VerifyP7S(inFile,sigFile)
If (success = false) Then
    TextBox1.Text = TextBox1.Text & crypt.LastErrorText & vbCrLf

    Exit Sub
End If




MsgBox("Success!")