MIME S/MIME Signing Algorithm Properties

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Demonstrates the properties that control S/MIME signing: SigningAlg (the RSA signature scheme, PKCS1-V1_5 or RSASSA-PSS), SigningHashAlg (the message-digest algorithm), Micalg and Protocol (the micalg and protocol parameters of a multipart/signed Content-Type), and UseXPkcs7 (whether historical x-pkcs7 media-type names are used). The properties are configured before creating a detached signature.

var
success: Integer;
mime: TChilkatMime;
pfxPassword: WideString;
cert: TChilkatCert;

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;

//  SigningAlg is the RSA signature scheme.  The default is PKCS1-V1_5; set RSASSA-PSS (or pss) for
//  RSASSA-PSS.
mime.SigningAlg := 'PKCS1-V1_5';

//  SigningHashAlg is the message-digest algorithm.  The default is sha256.
mime.SigningHashAlg := 'sha256';

//  Micalg and Protocol are the micalg and protocol parameters written into a multipart/signed
//  Content-Type header field.  They are normally set automatically, but can be controlled here.
mime.Micalg := 'sha-256';
mime.Protocol := 'application/pkcs7-signature';

//  UseXPkcs7 controls whether newly created S/MIME media types use the historical x-pkcs7 names.
mime.UseXPkcs7 := 0;

//  Load a signing certificate (with private key access) from a PFX.  The PFX password should come
//  from a secure source rather than being hard-coded.
pfxPassword := 'myPfxPassword';
cert := TChilkatCert.Create(Self);
success := cert.LoadPfxFile('qa_data/signer.pfx',pfxPassword);
if (success = 0) then
  begin
    Memo1.Lines.Add(cert.LastErrorText);
    Exit;
  end;

//  Create the detached signature using the algorithms configured above.
success := mime.AddDetachedSignature(cert.ControlInterface);
if (success = 0) then
  begin
    Memo1.Lines.Add(mime.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Signed with SigningAlg=' + mime.SigningAlg + ' SigningHashAlg=' + mime.SigningHashAlg);