Xbase++

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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LOCAL nSuccess
LOCAL oMime
LOCAL oCert
LOCAL oPrivKey

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 certificate and its private key separately.
oCert := CreateObject("Chilkat.Cert")
nSuccess := oCert:LoadFromFile("qa_data/signer.cer")
IF (nSuccess == 0)
    ? oCert:LastErrorText
    oMime:destroy()
    oCert:destroy()
    RETURN
ENDIF

oPrivKey := CreateObject("Chilkat.PrivateKey")
nSuccess := oPrivKey:LoadPemFile("qa_data/signer_privkey.pem")
IF (nSuccess == 0)
    ? oPrivKey:LastErrorText
    oMime:destroy()
    oCert:destroy()
    oPrivKey:destroy()
    RETURN
ENDIF

//  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.
nSuccess := oMime:AddDetachedSignaturePk(oCert, oPrivKey)
IF (nSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    oCert:destroy()
    oPrivKey:destroy()
    RETURN
ENDIF

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

? "Detached signature added."

oMime:destroy()
oCert:destroy()
oPrivKey:destroy()