Delphi ActiveX

Check for an S/MIME Signing Time

Demonstrates the Chilkat Mime.HasSignatureSigningTime method, which returns whether the signer at a zero-based index included a CMS signingTime signed attribute. The only argument is the signer index; use NumSignerCerts for the count.

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: A signing time records when the signer claims to have signed, which matters for auditing and for validating a certificate that has since expired. It is an optional signed attribute, so not every signature has one — this predicate lets you check before calling GetSignatureSigningTimeStr, avoiding an error for signers that omitted it. Being a signed attribute, it is covered by the signature and cannot be altered undetected.

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var
success: Integer;
mime: TChilkatMime;
n: Integer;
i: Integer;

begin
success := 0;

mime := TChilkatMime.Create(Self);
success := mime.LoadMimeFile('qa_data/signed.eml');
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

//  After verifying, check whether each signer included a CMS signingTime signed attribute.  The
//  only argument is the zero-based signer index.
success := mime.Verify();
if (success <> 1) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

n := mime.NumSignerCerts;

for i := 0 to n - 1 do
  begin
    if (mime.HasSignatureSigningTime(i)) then
      begin
        Memo1.Lines.Add('Signer ' + IntToStr(i) + ' included a signing time.');
      end
    else
      begin
        Memo1.Lines.Add('Signer ' + IntToStr(i) + ' did not include a signing time.');
      end;
  end;