Visual FoxPro

Create an Opaque Signature with a Separate Private Key

Demonstrates the Chilkat Mime.ConvertToSignedPk method, which creates an opaque 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: The separate-key form of ConvertToSigned, for when the certificate and private key are not bundled together. It produces the same opaque CMS signed-data result; only the source of the key material differs.

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Visual FoxPro

LOCAL lnSuccess
LOCAL loMime
LOCAL loCert
LOCAL loPrivKey

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 certificate and its private key separately.
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadFromFile("qa_data/signer.cer")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loMime
    RELEASE loCert
    CANCEL
ENDIF

loPrivKey = CreateObject('Chilkat.PrivateKey')
lnSuccess = loPrivKey.LoadPemFile("qa_data/signer_privkey.pem")
IF (lnSuccess = 0) THEN
    ? loPrivKey.LastErrorText
    RELEASE loMime
    RELEASE loCert
    RELEASE loPrivKey
    CANCEL
ENDIF

*  Create an opaque signature when the certificate and private key are supplied separately.  The
*  1st argument is the signer certificate and the 2nd is its private key.
lnSuccess = loMime.ConvertToSignedPk(loCert,loPrivKey)
IF (lnSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    RELEASE loCert
    RELEASE loPrivKey
    CANCEL
ENDIF

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

? "Message converted to an opaque signed message."

RELEASE loMime
RELEASE loCert
RELEASE loPrivKey