Sign a File to Create a .p7m File (using a PFX)

Visual Basic example to sign a file creating a .p7m file as output. The .p7m contains the signed contents of the original file. It can be verified and restored by calling VerifyP7M.

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 .p7m as output:
Dim inFile As String
inFile = "/Users/chilkat/testData/pdf/sample.pdf"
Dim outFile As String
outFile = "/Users/chilkat/testData/p7m/sample.pdf.p7m"
success = crypt.CreateP7M(inFile,outFile)
If (success = 0) Then
    Text1.Text = Text1.Text & crypt.LastErrorText & vbCrLf

    Exit Sub
End If

'  Verify and restore the original file:
crypt.SetVerifyCert cert

inFile = outFile
outFile = "/Users/chilkat/testData/pdf/restored.pdf"

success = crypt.VerifyP7M(inFile,outFile)
If (success = 0) Then
    Text1.Text = Text1.Text & crypt.LastErrorText & vbCrLf

    Exit Sub
End If

MsgBox "Success!"