[TmC]

OK...the problem is partly solved. Partly because one application begun to work perfeclty even under rad studio XE, while the other fails exactly as beginning. here i paste code from the first and the second:

WORKING APP (previously not working)

procedure TMainForm.BitBtn4Click(Sender: TObject);
var
  content, instr, opt: AnsiString;
  open: File;
begin
slist.Clear;
OD.DefaultExt := '.sif';
OD.Filter := 'Signatrol Instruction File|*.sif';
OD.Title := 'Please specify a valid Instruction File to load';
while OD.FileName = '' do
begin
OD.Execute;
try
begin
AssignFile(open,OD.FileName);
FileMode := fmOpenRead;
Reset(open,1);
SetLength(content,FileSize(open));
BlockRead(open,content[1],Length(content));
CloseFile(open);
end
except
Messagebox(Application.Handle,'Error while opening the file. Please check that the file exists and it is a valid Signatrol Instruction File and try again!','Severe',MB_ICONERROR);
Exit;
end;
end;
if Copy(content,1,10) <> 'SIGNATROLV' then
begin
Messagebox(Application.Handle,'This is not a valid Signatrol Instruction File. Please specify a valid Signatrol Instruction File and try again!','Severe',MB_ICONERROR);
Exit;
end;
OD.FileName := '';
content := Copy(content,Pos('$',content)+1,Length(content));
content := RC6Decrypt(content,'SIGNATROLV1183919102011');
if Copy(SHA1(Copy(content,1,Pos('###BSB###',content)-1)),1,40) <> Copy(content,Pos('###BSB###',content)+9,40) then
begin
Messagebox(Application.Handle,'File Corrupted! This file was damaged by a Virus or a Bad Sector and can''t be used anymore. Please specify another file try again!','Severe',MB_ICONERROR);
Exit;
end;
content := Copy(content,1,Pos('###BSB###', content) -1);
instr := Copy(content,1,Pos('###EDB###',content)+8);
opt := Copy(content,Pos('###BOB###',content),Length(content));
instr := StringReplace(instr,'###BDB###','',[rfReplaceAll]);
instr := StringReplace(instr,'###EDB###','',[rfReplaceAll]);
while Pos('#',instr) <> 0 do
begin
slist.AddItem(Copy(instr,1,Pos('#',instr)-1),nil);
instr := Copy(instr,Pos('#',instr)+1,Length(instr));
end;
slist.AddItem(instr,nil);
opt := StringReplace(opt,'###BOB###','',[rfReplaceAll]);
opt := StringReplace(opt,'###EOB###','',[rfReplaceAll]);
txtSpanS.Text := opt;
end;

NOT WORKING APP

function TLIC.intCheckLicKey(actcode: AnsiString): boolean;
var
  licdata: array of AnsiString;
  tmp, xx: String;
  ok: boolean;
  r, s, generator : AnsiString;
  p, q, g, y: TBIGInt;
  z,i: integer;
begin
actcode := licdata[0] + #13#10 + licdata[1] + #13#10 + licdata[2] + #13#10 + licdata[3] + #13#10 + licdata[4] + #13#10 + licdata[5] + #13#10 + licdata[6] + #13#10 + licdata[7] + #13#10 + licdata[8] + #13#10 + licdata[9] + #13#10 + licdata[10] + #13#10 + licdata[14];
s := licdata[11] + licData[12];
s := StringReplace(s,'-','',[rfReplaceAll]);
ConvertHexStringToBase256String(s,s);
r := intRC6Decrypt(Base64DecodeStr(licdata[13]),intCertificate.LSSigKeySeed); <--- I BELIEVE THIS IS THE CAUSE OF THE FAILURE
Base10StringToBIGInt(intCertificate.LSSigKeyQ,q);
Base10StringToBIGInt(intCertificate.LSSigKeyP,p);
Base10StringToBIGInt(intCertificate.LSSigKeyG,g);
Base10StringToBIGInt(intCertificate.LSSigKeyY,y);
DSAVerify(p, q, g, y, actcode, r, s, ok);
if ok then
begin
//GOOD BOY
end
else
begin
//BAD BOY
end;

The actual DSAVerify works very good, because if I replace the decrypted (partially incorrectly) from the memory loading from an external textbox (like told upper in this thread) it returns true. The same exact code in Delphi 7 works, while in Rad Studio XE does not.