Xbase++

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 nSuccess
LOCAL oMime
LOCAL cPfxPassword
LOCAL oCert
LOCAL nTransferHeaderFields

nSuccess := 0

oMime := CreateObject("Chilkat.Mime")
nSuccess := oMime:SetBodyFromPlainText("This message will be signed.")
IF (nSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    RETURN
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.
cPfxPassword := "myPfxPassword"
oCert := CreateObject("Chilkat.Cert")
nSuccess := oCert:LoadPfxFile("qa_data/signer.pfx", cPfxPassword)
IF (nSuccess == 0)
    ? oCert:LastErrorText
    oMime:destroy()
    oCert:destroy()
    RETURN
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.
nTransferHeaderFields := 1
nSuccess := oMime:AddDetachedSignature2(oCert, nTransferHeaderFields)
IF (nSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    oCert:destroy()
    RETURN
ENDIF

nSuccess := oMime:SaveMime("qa_output/signed.eml")
IF (nSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    oCert:destroy()
    RETURN
ENDIF

? "Detached signature added (headers transferred)."

oMime:destroy()
oCert:destroy()