PKCS7 Decrypt MIME

Loads a PKCS7 encrypted MIME file and decrypts.

Download Chilkat MIME ActiveX

Dim mime As New ChilkatMime

Dim success As Long
success = mime.UnlockComponent("Anything for 30-day trial.")
If (success = 0) Then
    Text1.Text = Text1.Text & mime.LastErrorText & vbCrLf
    Exit Sub
End If

'  Load the MIME
success = mime.LoadMimeFile("encrypted.mim")
If (success = 0) Then
    Text1.Text = Text1.Text & mime.LastErrorText & vbCrLf
    Exit Sub
End If

'  Decrypt...
success = mime.Decrypt()
If (success = 0) Then
    Text1.Text = Text1.Text & mime.LastErrorText & vbCrLf
    Exit Sub
End If

'  Display the decrypted MIME:
Text1.Text = Text1.Text & mime.GetMime() & vbCrLf

'  How is it possible to magically decrypt with no information?
'  Answer: It is possible to decrypt if the certificate with private key
'  needed for decryption was previously installed onto the
'  Windows computer.  PKCS7 encrypted (enveloped) data always
'  includes information about the certificate required for
'  decryption.  Chilkat uses it to automatically search the
'  Windows registry-based certificate stores to find the
'  certificate.

'  If the certificate required for decryption was not installed, but
'  you have a PFX file containing the cert + private key,
'  then it may be used like this:

'  The AddPfxSourceFile and/or AddPfxSourceData
'  methods may be called one or more times (one per PFX)
'  to add sources from which the MIME component will
' search for certificates and private keys when decrypting.
Dim pfxPassword As String
pfxPassword = "myPassword"
success = mime.AddPfxSourceFile("myCertAndPrivateKey.pfx",pfxPassword)
If (success = 0) Then
    Text1.Text = Text1.Text & mime.LastErrorText & vbCrLf
    Exit Sub
End If

'  Now call Decrypt, and it will search the PFX sources
'  previously added...