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

VB.NET 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 .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 .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 = false) Then
    TextBox1.Text = TextBox1.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 = false) Then
    TextBox1.Text = TextBox1.Text & crypt.LastErrorText & vbCrLf

    Exit Sub
End If




MsgBox("Success!")