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

Visual Basic 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 Crypt ActiveX

Dim crypt As New ChilkatCrypt2

'  Any string argument automatically begins the 30-day trial.
Dim success As Long
success = crypt.UnlockComponent("30-day trial")
If (success <> 1) Then
    Text1.Text = Text1.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 ChilkatCertStore
success = certStore.LoadPfxFile(pfxFilename,pfxPassword)
If (success <> 1) Then
    Text1.Text = Text1.Text & certStore.LastErrorText & vbCrLf
    Exit Sub
End If

Dim cert As ChilkatCert
Set cert = certStore.FindCertBySubjectCN(signingCertSubject)
If (cert Is Nothing ) Then
    Text1.Text = Text1.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 = 0) Then
    Text1.Text = Text1.Text & crypt.LastErrorText & vbCrLf

    Exit Sub
End If

success = crypt.VerifyP7S(inFile,sigFile)
If (success = 0) Then
    Text1.Text = Text1.Text & crypt.LastErrorText & vbCrLf

    Exit Sub
End If

MsgBox "Success!"