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uses
crt,
dos;
var
key:string[8];
{ decode file ---------------------------------------------------------------}
{your code here}
procedure decode(infname:pathstr);
var
infile,outfile:file;
fdir:dirstr; fname:namestr; fext:extstr;
dbuf,sbuf:pointer;
idx,i,j,srcseg,srcofs,dstseg,dstofs,start,csize:word;
src,rep:byte;
begin
if maxavail<2*65500 then Begin
Writeln(#13#10,'No Memory');
halt;
End;
getmem(dbuf,65500);
getmem(sbuf,65500);
srcseg:=seg(sbuf^); srcofs:=ofs(sbuf^);
dstseg:=seg(dbuf^); dstofs:=ofs(dbuf^); start:=dstofs;
assign(infile,infname);
{$i-} reset(infile,1); {$i+}
if ioresult<>0 then Begin
Writeln(#13#10'File I/O!');
halt;
End;
if filesize(infile)>65500 then halt;
blockread(infile,sbuf^,filesize(infile));
csize:=filesize(infile);
close(infile);
randseed:=ord(key[length(key)]); j:=0;
for i:=0 to csize do begin
mem[srcseg:srcofs+i]:=mem[srcseg:srcofs+i] xor
(ord(key[j])+random(ord(key[j])));
j:=1+j mod 8;
end;
idx:=0;
while idx
0 then Begin
Writeln(#13#10'Output Error!');
halt(4);
End;
blockwrite(outfile,key[1],length(key)); {so I know which key did it!}
blockwrite(outfile,dbuf^,csize); {un encoded}
close(outfile);
freemem(sbuf,65500);
freemem(dbuf,65500);
end;
{ main ----------------------------------------------------------------------}
Procedure ShowFile(FName:String); {just a test ... not used in live version!}
Var
T:Text;
S:String;
Begin
Assign(T,FName);
ReSet(T);
While not eof(t) do begin
{$I-} Readln(t,s); {$I+}
Writeln(s);
End;
Close(T);
End;
Var
Cnt1:Integer; {character 1}
Cnt2:Integer; {2}
Cnt3:Integer; {3}
Cnt4:Integer; {4}
Cnt5:Integer; {5}
Cnt6:Integer; {6}
Cnt7:Integer; {7}
Cnt8:Integer; {8}
Ch:Char; {did I press a local key?}
outfile:file; {just for making an empty file to append to}
Dumb:Byte; {dumb!}
done:boolean; {tried from '' to #255#255#255#255#255#255#255#255}
begin
assign(outfile,'hack.org');
{$i-} rewrite(outfile,1); {$i+}
Close(outfile); {made a 0 byte file to append to}
{init}
Cnt1:=0;
Cnt2:=0;
Cnt3:=0;
Cnt4:=0;
Cnt5:=0;
Cnt6:=0;
Cnt7:=0;
Cnt8:=0;
done:=false;
While not done do begin
{not I inc 1 char at a time}
Inc(Cnt1);
If Cnt1>255 then Begin
Cnt1:=0;
Inc(Cnt2);
End;
If Cnt2>255 then Begin
Cnt2:=0;
Inc(Cnt3);
End;
If Cnt3>255 then Begin
Cnt3:=0;
Inc(Cnt4);
End;
If Cnt4>255 then Begin
Cnt4:=0;
Inc(Cnt5);
End;
If Cnt5>255 then Begin
Cnt5:=0;
Inc(Cnt6);
End;
If Cnt6>255 then Begin
Cnt6:=0;
Inc(Cnt7);
End;
If Cnt7>255 then Begin
Cnt7:=0;
Inc(Cnt8);
End;
If Cnt8>255 then Halt;
Key:='';
If Cnt1<>0 then key:=key+chr(cnt1);
If Cnt2<>0 then key:=key+chr(cnt2);
If Cnt3<>0 then key:=key+chr(cnt3);
If Cnt4<>0 then key:=key+chr(cnt4);
If Cnt5<>0 then key:=key+chr(cnt5);
If Cnt6<>0 then key:=key+chr(cnt6);
If Cnt7<>0 then key:=key+chr(cnt7);
If Cnt8<>0 then key:=key+chr(cnt8);
{call your decode method}
Decode('HACK.DAT');
{ShowFile('HACK.ORG');}
{so I can see its running:}
Writeln('KEY: ',Key);
If Keypressed then Begin
Ch:=Readkey;
if ch=#27 then halt;
End;
End;
(* if (paramcount<>2) or (pos('?',paramstr(1))>0) then begin
writeln('Syntax: DECODE
');
writeln('Both parameters are required!');
halt;
end;
key:=paramstr(2);
decode(paramstr(1));
writeln('File successfully decoded!'); *)
end.
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