Delphi ActiveX

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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var
success: Integer;
email: TChilkatEmail;
cert: TChilkatCert;

begin
success := 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.

email := TChilkatEmail.Create(Self);
email.Subject := 'Signed email';
email.Body := 'This message will be sent with a digital signature.';
email.From := 'alice@example.com';
email.AddTo('Bob','bob@example.com');

//  Load the signing certificate (including its private key) from a PFX file.
//  The 2nd argument is the PFX password.
cert := TChilkatCert.Create(Self);
success := cert.LoadPfxFile('qa_data/certs/signer.pfx','pfx_password');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

//  Provide the signing certificate.
success := email.SetSigningCert(cert.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(email.LastErrorText);
    Exit;
  end;

//  Request that the email be sent with a digital signature.
email.SendSigned := 1;

Memo1.Lines.Add('SendSigned = ' + IntToStr(Ord(email.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.