Visual FoxPro

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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LOCAL lnSuccess
LOCAL loMime
LOCAL lcPfxPassword
LOCAL loCert
LOCAL lnTransferHeaderFields

lnSuccess = 0

loMime = CreateObject('Chilkat.Mime')
lnSuccess = loMime.SetBodyFromPlainText("This message will be signed.")
IF (lnSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    CANCEL
ENDIF

*  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.
lcPfxPassword = "myPfxPassword"
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/signer.pfx",lcPfxPassword)
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loMime
    RELEASE loCert
    CANCEL
ENDIF

*  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.
lnTransferHeaderFields = 1
lnSuccess = loMime.AddDetachedSignature2(loCert,lnTransferHeaderFields)
IF (lnSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    RELEASE loCert
    CANCEL
ENDIF

lnSuccess = loMime.SaveMime("qa_output/signed.eml")
IF (lnSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    RELEASE loCert
    CANCEL
ENDIF

? "Detached signature added (headers transferred)."

RELEASE loMime
RELEASE loCert