29A Issue 03 02 12

eZine lover (@eZine)

Published in 

29A

 · 4 years ago

  

{ 

 Ok, this is a very quick hack to decrypt TBSCAN32.EXE. This ain't fool 
 proof, but TBSCAN ain't either :-) Once you know how it encrypts, it's very 
 easy to decrypt, as the encryption is fairly standard. 

 Rajaat, November 1998 

} 

uses dos; 

var buffer : array[0..20000] of word; 
    f : file; 
    i : word; 
    l : word; 
    a : word; 

begin 
  assign(f,'TBSCAN32.EXE'); 
  reset(f,1); 
  blockread(f, buffer, filesize(f),l); 
  seek(f,0); 
  for i := $149 to filesize(f) div 2 do 
  begin 
    a := buffer[i]; 
    a := a xor $3fe; 
    a := a xor $c9a4; 
    asm 
      mov ax,a 
      rol ax,1 
      mov a,ax 
    end; 
    buffer[i] := a; 
  end; 
  blockwrite(f, buffer, filesize(f)); 
  close(f); 
end.