B4X

Encrypt MIME for Multiple Recipients

Demonstrates encrypting the current MIME entity for several recipients at once. A certificate is added for each recipient with AddEncryptCert, and EncryptN then produces a single CMS/PKCS #7 message that each recipient can independently decrypt.

The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background. When a message targets more than one recipient, each recipient's certificate is added to the internal list and EncryptN wraps the message key separately for each one. Any single recipient can then decrypt with their own private key.

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Dim success As Boolean = False

Dim mime As ChilkatMime
mime.Initialize
success = mime.SetBodyFromPlainText("This message will be encrypted.")
If success = False Then
    Log(mime.LastErrorText)
    Return
End If


'  Add a certificate for each intended recipient.  Every recipient receives an independently
'  wrapped copy of the message key.
Dim cert1 As ChilkatCert
cert1.Initialize("cert1")
success = cert1.LoadFromFile("qa_data/recipient1.cer")
If success = False Then
    Log(cert1.LastErrorText)
    Return
End If

success = mime.AddEncryptCert(cert1)
If success = False Then
    Log(mime.LastErrorText)
    Return
End If


Dim cert2 As ChilkatCert
cert2.Initialize("cert2")
success = cert2.LoadFromFile("qa_data/recipient2.cer")
If success = False Then
    Log(cert2.LastErrorText)
    Return
End If

success = mime.AddEncryptCert(cert2)
If success = False Then
    Log(mime.LastErrorText)
    Return
End If


'  Encrypt for every added recipient at once.
success = mime.EncryptN
If success = False Then
    Log(mime.LastErrorText)
    Return
End If


success = mime.SaveMime("qa_output/encrypted_multi.eml")
If success = False Then
    Log(mime.LastErrorText)
    Return
End If

Log("Message encrypted for multiple recipients.")