B4X

Add a Detached Signature (Header Placement Control)

Demonstrates the Chilkat Mime.AddDetachedSignature2 method, which creates the same multipart/signed structure as AddDetachedSignature, with a second argument controlling whether the existing message header fields are transferred to the new outer entity.

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: Signing wraps the content in a new outer multipart/signed, which raises the question of where the message-level headers (Subject, From, To) should live. This variant lets you choose: transfer them up to the outer entity so the signed message looks like a normal email, or leave them on the inner part. Transferring is typical for email; the finer control matters when the signed entity is embedded in a larger structure.

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B4X

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 signing certificate (which must have access to its private key) from a PFX file.
'  The PFX password should come from a secure source rather than being hard-coded.
Dim pfxPassword As String = "myPfxPassword"
Dim cert As ChilkatCert
cert.Initialize("cert")
success = cert.LoadPfxFile("qa_data/signer.pfx", pfxPassword)
If success = False Then
    Log(cert.LastErrorText)
    Return
End If


'  AddDetachedSignature2 is the same as AddDetachedSignature, but the 2nd argument controls whether
'  the existing message header fields are transferred to the new outer multipart/signed entity.
Dim transferHeaderFields As Boolean = True
success = mime.AddDetachedSignature2(cert, transferHeaderFields)
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 (headers transferred).")