Question

I use following procedure to encode stream.

procedure SaveEncodedStream(Strm:TStream; LicFileName:String);
var
   C:TCodec;
    CL:TCryptographicLibrary;
    Sg:TSignatory;
    KFS,DFS:TFileStream;
    Dir:String;
begin
   CL:=TCryptographicLibrary.Create(nil);
   C:=TCodec.Create(nil);
  SG:=TSignatory.Create(nil);

   Dir :=  ExtractFilePath(ParamStr(0));
   KFS:=TFileStream.Create(Dir+PublicKeyFile,fmOpenRead);
   DFS:=TFileStream.Create(LicFileName,fmCreate);

  try
  C.CryptoLibrary:=CL;
  C.BlockCipherId := 'native.RSA';
  C.ChainModeId := 'native.CBC';
  C.AsymetricKeySizeInBits := 1024;
  SG.Codec:=C;
  SG.LoadKeysFromStream(KFS,[partPublic]);
  C.EncryptStream(Strm,DFS);
 finally
  CL.Free;
  C.Free;
  SG.Free;
  KFS.Free;
  DFS.Free;
 end;
end;

And receive “Wrong Mode” error on

C.EncryptStream(Strm,DFS); call

Stepping into the code I discovered that it even does not try to load keys as Codec is not initialized. When I place componets on the form – everything works. But I do not need Form or DataModule.

Answer 1

Have not found solution to get rid of DataModule. It looks like components need one to properly initialize themselves. So as workaround I have created global DataModule with all components configured in design mode. I use that module in SaveEncodedStream like that:

uses 
  ... EncryptDataModule;
 ...
var 
   BeenHere:Boolean = false;
 ...
procedure SaveEncodedStream(Strm:TStream; LicFileName:String);
 var
   KFS,DFS:TFileStream;
   Dir:String;
begin

   Dir :=  ExtractFilePath(ParamStr(0));
   KFS:=TFileStream.Create(Dir+PublicKeyFile,fmOpenRead);
   DFS:=TFileStream.Create(LicFileName,fmCreate);

   try
    DataModule.SG.LoadKeysFromStream(KFS,[partPublic]);
    if BeenHere then DataModule.C.Reset;  
    DataModule.C.EncryptStream(Strm,DFS);
    BeenHere:=true; 
  finally
   KFS.Free;
   DFS.Free;
  end;
end;