B4X

Add a Detached Signature with a Separate Private Key

Demonstrates the Chilkat Mime.AddDetachedSignaturePk method, which creates a detached signature using a signer certificate and its separately supplied private key. The first argument is the Cert and the second is the PrivateKey.

Note: 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: Sometimes the certificate and its private key live apart — a .cer alongside a PEM key file, for instance — rather than bundled in a single PFX. This method pairs them explicitly for signing, whereas AddDetachedSignature expects a Cert that already provides its key. The result is the same multipart/signed message.

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Dim success As Boolean = False

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

'  Load the certificate and its private key separately.
Dim cert As ChilkatCert
cert.Initialize("cert")
success = cert.LoadFromFile("qa_data/signer.cer")
If success = False Then
    Log(cert.LastErrorText)
    Return
End If


Dim privKey As ChilkatPrivateKey
privKey.Initialize("privKey")
success = privKey.LoadPemFile("qa_data/signer_privkey.pem")
If success = False Then
    Log(privKey.LastErrorText)
    Return
End If


'  Create a detached signature when the certificate and private key are supplied separately.  The
'  1st argument is the signer certificate and the 2nd is its private key.
success = mime.AddDetachedSignaturePk(cert, privKey)
If success = False Then
    Log(mime.LastErrorText)
    Return
End If


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

Log("Detached signature added.")