Visual FoxPro

Send an Email with a Digital Signature

Demonstrates the Chilkat Email.SendSigned property. Set it to true to have the email sent with a digital signature (the default is false). Signing also requires a certificate with access to its private key. This example loads that certificate (and its private key) from a PFX file with Cert.LoadPfxFile, supplies it via SetSigningCert, and enables signed sending.

Background: Signing is the mirror image of encrypting. To encrypt for a recipient you use their public certificate; to sign you use your own private key, and recipients verify with your public certificate. A signature does not hide the message — a signed email is still readable by anyone — but it proves who sent it and guarantees the content was not tampered with. A PFX (also called PKCS#12, .pfx or .p12) is a password-protected file that bundles a certificate together with its private key, making it a convenient single-file source for signing credentials.

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LOCAL lnSuccess
LOCAL loEmail
LOCAL loCert

lnSuccess = 0

*  Demonstrates the Email.SendSigned property with a full signing setup.  Set SendSigned
*  to true to have the email sent with a digital signature.  Signing requires a certificate
*  with access to its private key, which we load here from a PFX (.pfx / .p12) file.

loEmail = CreateObject('Chilkat.Email')
loEmail.Subject = "Signed email"
loEmail.Body = "This message will be sent with a digital signature."
loEmail.From = "alice@example.com"
loEmail.AddTo("Bob","bob@example.com")

*  Load the signing certificate (including its private key) from a PFX file.
*  The 2nd argument is the PFX password.
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/certs/signer.pfx","pfx_password")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loEmail
    RELEASE loCert
    CANCEL
ENDIF

*  Provide the signing certificate.
lnSuccess = loEmail.SetSigningCert(loCert)
IF (lnSuccess = 0) THEN
    ? loEmail.LastErrorText
    RELEASE loEmail
    RELEASE loCert
    CANCEL
ENDIF

*  Request that the email be sent with a digital signature.
loEmail.SendSigned = 1

? "SendSigned = " + STR(loEmail.SendSigned)

*  Note: The path "qa_data/certs/signer.pfx" is a relative local filesystem path,
*  relative to the current working directory of the running application.

RELEASE loEmail
RELEASE loCert