Decrypt with BlowFish and load into DBGrid
lazarus / 16-Databases

----------------------------------------------------------------------
CyberFilth · 2016-03-21 12:26

Hi,

I have a small, simple program that stores users login details in an
unencrypted CSV file and loads them into a DBGrid,
https://sourceforge.net/projects/lazlock/files/0.4/
I want to be able to encrypt the file with BlowFish before saving it
which I seem to have successfully done with this:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i const 
{$IFDEF Windows}  C_FNAME = 'files\data.csv';  {$ENDIF}  {$IFDEF
Linux}  C_FNAME = 'files/data.csv';  {$ENDIF} procedure
TLazLock.EncryptSaveClick(Sender: TObject);var  encrypt:
TBlowFishEncryptStream;  SSun, SSen, SStream: TStringStream;  SList:
TStringList;  FileContents: string; begin 
 FileContents:=Utf8Encode(ZMQueryDataset1.TableName); // Copy the
contents of the DBGrid to FileContents 
 SSen:=TStringStream.Create(''); 
 encrypt:=TBlowFishEncryptStream.Create(PasswordKey,SSen); // Encrypt
with user entered PasswordKey 
 encrypt.Write(FileContents[1],Length(FileContents));   encrypt.Free; 
 SSun:=TStringStream.Create('');   SSun.Position:=0; 
 SStream:=TStringStream.Create(SSen.DataString);   SList:=
TStringList.Create;   SList.LoadFromStream(SStream); 
 SList.SaveToFile(C_FNAME);   SSun.Free;   SSen.Free; 
 SStream.Free;end;
I'm struggling to then load the file back into the DBGrid. I've tried
using the procedure below but with no success.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TLazLock.DecryptAndOpenFile; { TODO : Use a constant for the password
during testing }var   MemStream: TMemoryStream;   SL:
TStringList;begin    MemStream := TMemoryStream.Create;   
MemStream.LoadFromFile(C_FNAME);    DecryptionStream:=
TBlowFishDeCryptStream.Create(PasswordKey,MemStream);    SL :=
TStringlist.Create;    SL.LoadFromStream(MemStream);   
 DBGrid1.Columns[2].PickList.Assign(SL);   
 ZMQueryDataset1.LoadFromTable;     MemStream.Free;     SL.Free;end;
I'm definitely at the "a little knowledge is dangerous" end of the
coding spectrum but wondered if anyone could give me some pointers to
the problem. I'm assuming that I can't just load a StringList into a
DBGrid this way but also wondered if the method I've used for
decrypting the file could be an issue?
The full code is at
https://sourceforge.net/projects/lazlock/files/0.5.5/

Any help would be appreciated.

----------------------------------------------------------------------
dogriz · 2016-03-22 06:38

I don't know if this can help you in any way, but here's what i used
with ClientDataSet in Delphi:
Code: [Select]procedure TForm1.clientDataSet1GetText(Sender: TField;
  var Text: String; DisplayText: Boolean);
begin
  if Sender.IsNull then
    Text:='0'
  else
    Text:=Sender.AsString;
end;This code has nothing to do with encryption, but I hope you get
the idea.

----------------------------------------------------------------------
vfclists · 2016-03-31 23:03

You need to use the OnGetText event of the TField to decode the text.

----------------------------------------------------------------------
CyberFilth · 2016-04-06 12:33

Well previously, I successfully loaded an unencrypted CSV file into a
DBGrid with;

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TLazLock.OpenFile;var   SL: TStringList; 
 MyStringStream:TStringStream;begin     SL:= TStringList.Create;   
 SL.LoadFromFile(C_FNAME);   
 DBGrid1.Columns[2].PickList.Assign(SL);   
 ZMQueryDataset1.LoadFromTable;     SL.Free; end;
I was hoping to combine this with a small program I wrote that loaded
an encrypted filestream and decrypted it, to come up with this;

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TLazLock.DecryptAndOpenFile;var   DecryptionStream:
TBlowFishDeCryptStream;   MyStringStream, SSen, SStream2:
TStringStream;   SL, SL2: TStringList;   tempdec: string;begin   
 SL:= TStringList.Create;     SL.LoadFromFile(C_FNAME);    
 SStream2:=TStringStream.Create('');     SL.SaveToStream(SStream2);  
 SL.Free;     SSen:=TStringStream.Create(SStream2.DataString);   
 SStream2.Free;   
 DecryptionStream:=TBlowFishDeCryptStream.Create(password,SSen);   
 SSen.Position:=0;     SetLength(tempdec,SSen.Size);   
 DecryptionStream.Read(tempdec[1],SSen.Size);   
 SL2:=TstringList.Create;     SL2.Text:=tempdec;   
 DBGrid1.Columns[2].PickList.Assign(SL2);   
 ZMQueryDataset1.LoadFromTable;     SL2.Free; end;
But this doesn't display anything. I can decrypt the file and display
it in a TMemo however... just not a DBGrid.

----------------------------------------------------------------------
Mike.Cornflake · 2016-04-06 13:18

I'm not sure how your original code worked.

QuoteCode: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
DBGrid1.Columns[2].PickList.Assign(SL);
A PickList is a dropdownlist that's added to that specific column.  I
can't see how that populates the DBGrid

QuoteCode: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
ZMQueryDataset1.LoadFromTable;
This makes a more sense.  It's the contents of ZMSQuery that you're
displaying in the DBGrid, so in order to populate the Grid, you need
the ZMSQuery populating first.

I've never used ZMSQL, but from the wiki

http://wiki.freepascal.org/ZMSQL

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
LoadFromTable; //Loads data (or data and schema) from a .csv file
(TableName.csv), set in property TableName, from path specified in
ZMConnection property
So, what was possibly happening in your original code, was that you
had the TableName property set in the Object Inspector, and this was
pointing to a valid CSV on your system somewhere.  When you fired the
LoadFromTable, it's that CSV that was loaded, nothing to do with
PickList code.

IF my guess is right, then all you need to do is change your routine
to something like..

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TLazLock.DecryptAndOpenFile;var   DecryptionStream:
TBlowFishDeCryptStream;   MyStringStream, SSen, SStream2:
TStringStream;   SL, SL2: TStringList;   tempdec: string;begin   
 SL:= TStringList.Create;     SL.LoadFromFile(C_FNAME);   
 SStream2:=TStringStream.Create('');     SL.SaveToStream(SStream2);  
 SL.Free;     SSen:=TStringStream.Create(SStream2.DataString);   
 SStream2.Free;   
 DecryptionStream:=TBlowFishDeCryptStream.Create(password,SSen);   
 SSen.Position:=0;     SetLength(tempdec,SSen.Size);   
 DecryptionStream.Read(tempdec[1],SSen.Size);   
 SL2:=TstringList.Create;     SL2.Text:=tempdec;   
 //DBGrid1.Columns[2].PickList.Assign(SL2);   
 SL2.SaveToFile('C:\Temp\test.csv');       ZMConnection.Path :=
'C:\Temp';  { Wild guess that this is how you set the path, and that
this is what you called your connection }   
 ZMQueryDataset1.TableName := 'test.csv';        
 ZMQueryDataset1.LoadFromTable;     SL2.Free;end;
Obviously, this ('C:\Temp\test.csv') is a hack :-)   You'd actually
want to investigate loading ZMQuery from a stream, not a file.  I
couldn't find that info in the wiki...

----------------------------------------------------------------------
CyberFilth · 2016-04-06 14:30

I think you're right!
I'll check properly when I finish work but I believe that the
tablename was originally set in the Object Inspector...

I'll play around with it later and see if I can get this working.
I'll also look into loading the ZMQuery from a stream as I don't want
to save an unencrypted version of the file back to disk.

Thanks for looking into this!

----------------------------------------------------------------------
Mike.Cornflake · 2016-04-06 15:18

No probs.

Turns out ZMQuery is descended from TBufDataset, so should handle the
streaming.

Quickly skimmed this - may help
http://wiki.freepascal.org/How_to_write_in-
memory_database_applications_in_Lazarus/FPC

and this entire topic :-)  Someone may have posted something relevant
along the way...
http://forum.lazarus.freepascal.org/index.php/topic,13821.105.html