VB.NET

Specify a Certificate for Encrypted Email

Demonstrates the Chilkat Email.AddEncryptCert method, which explicitly specifies a certificate to use when sending encrypted email. Call it once per recipient certificate; ClearEncryptCerts clears the list. This example loads a recipient certificate, registers it, and enables encrypted sending.

Background: When encrypting to multiple people, each recipient needs to be able to decrypt with their own private key. S/MIME handles this by encrypting the message's one-time content key separately under each recipient's public certificate and including all of those wrapped keys in the message. AddEncryptCert is how you build that recipient list — one call per certificate — giving explicit control over exactly whose certificates are used rather than relying on automatic lookup.

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Dim success As Boolean = False

'  Demonstrates the AddEncryptCert method, which explicitly specifies a certificate for
'  sending encrypted email.  Call it once per recipient certificate.  Use ClearEncryptCerts
'  to clear the list.

Dim email As New Chilkat.Email
email.Subject = "Encrypted email"
email.Body = "Encrypted to the specified recipient certificate(s)."
email.From = "alice@example.com"
email.AddTo("Bob","bob@example.com")

'  Load a recipient certificate (public key) and add it to the encryption cert list.
Dim cert As New Chilkat.Cert
success = cert.LoadFromFile("qa_data/certs/recipient.cer")
If (success = False) Then
    Debug.WriteLine(cert.LastErrorText)
    Exit Sub
End If


success = email.AddEncryptCert(cert)
If (success = False) Then
    Debug.WriteLine(email.LastErrorText)
    Exit Sub
End If


'  Request encrypted sending.
email.SendEncrypted = True

Debug.WriteLine("Added the recipient's encryption certificate.")

'  Note: The path "qa_data/certs/recipient.cer" is a relative local filesystem path,
'  relative to the current working directory of the running application.