Delphi DLL

Check if a MIME Entity is Signed (S/MIME)

Demonstrates the Chilkat Mime.IsSigned method, which returns whether the entity is a complete CMS/PKCS #7 signed S/MIME wrapper, including detached multipart/signed and opaque forms. It takes no arguments.

Note: The file path is relative to the application's current working directory. Absolute paths may also be used. Supply the path to your own file.

Background: Before verifying a signature you need to know one is present, and this is the check. A signed S/MIME message comes in two shapes — detached (multipart/signed, signature alongside the content) and opaque (application/pkcs7-mime, content wrapped inside the signature) — and this recognizes both. Follow a true result with Verify.

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var
success: Boolean;
mime: HCkMime;

begin
success := False;

//  Demonstrates the Mime.IsSigned method, which returns whether the entity is a complete CMS/PKCS #7 signed S/MIME wrapper.  It takes no arguments.

mime := CkMime_Create();
success := CkMime_LoadMimeFile(mime,'qa_data/signed.eml');
if (success = False) then
  begin
    Memo1.Lines.Add(CkMime__lastErrorText(mime));
    Exit;
  end;

if (CkMime_IsSigned(mime)) then
  begin
    Memo1.Lines.Add('This is a signed S/MIME message.');
  end
else
  begin
    Memo1.Lines.Add('This is not a signed S/MIME message.');
  end;

CkMime_Dispose(mime);