Delphi ActiveX

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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var
success: Integer;
mime: TChilkatMime;
cert: TChilkatCert;
privKey: TPrivateKey;

begin
success := 0;

mime := TChilkatMime.Create(Self);
success := mime.SetBodyFromPlainText('This message will be signed.');
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;
//  Load the certificate and its private key separately.
cert := TChilkatCert.Create(Self);
success := cert.LoadFromFile('qa_data/signer.cer');
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

privKey := TPrivateKey.Create(Self);
success := privKey.LoadPemFile('qa_data/signer_privkey.pem');
if (success = 0) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

//  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.
success := mime.AddDetachedSignaturePk(cert.ControlInterface,privKey.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

success := mime.SaveMime('qa_output/signed.eml');
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;
Memo1.Lines.Add('Detached signature added.');