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Add an S/MIME Detached Signature

Demonstrates the Chilkat Mime.AddDetachedSignature method, which creates an S/MIME detached signature. The only argument is the signing Cert, which must have access to its private key. On success the entity becomes a multipart/signed with the content and a separate signature part.

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: A detached signature (multipart/signed) keeps the original content readable alongside a separate signature part — so recipients whose software does not understand S/MIME still see the message, they just cannot verify it. That backward compatibility makes detached the usual choice for signed email. The signer proves authorship with a certificate that carries its private key.

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llSuccess = .F.

loMime = createobject("CkMime")
llSuccess = loMime.SetBodyFromPlainText("This message will be signed.")
if (llSuccess = .F.) then
    ? loMime.LastErrorText
    release loMime
    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.
lcPfxPassword = "myPfxPassword"
loCert = createobject("CkCert")
llSuccess = loCert.LoadPfxFile("qa_data/signer.pfx",lcPfxPassword)
if (llSuccess = .F.) then
    ? loCert.LastErrorText
    release loMime
    release loCert
    return
endif

//  Create an S/MIME detached signature.  The object becomes a multipart/signed entity with the
//  original content and a separate signature part.
llSuccess = loMime.AddDetachedSignature(loCert)
if (llSuccess = .F.) then
    ? loMime.LastErrorText
    release loMime
    release loCert
    return
endif

llSuccess = loMime.SaveMime("qa_output/signed.eml")
if (llSuccess = .F.) then
    ? loMime.LastErrorText
    release loMime
    release loCert
    return
endif

? "Detached signature added."


release loMime
release loCert