Ne bavim se kriptografijom,ali me je nesto zaintrigiralo prilikom pisanja jednog programa u Pascal-u.
U pitanju je veoma jednostavan program (koder) za koji sam odmah napisao i dekoder. Kodovi slede:
program Koder;
var
f,g:text;
ch:char;
begin
assign(f,'plain.txt'); reset(f);
assign(g,'kodiran.txt'); rewrite(g);
while not eof(f) do
begin
while not eoln(f) do
begin
read(f,ch);
ch:=succ(ch);
write(g,ch);
end;
readln(f); writeln(g);
end;
close(f); close(g)
end.
program Dekoder;
var
f,g:text;
ch:char;
begin
assign(f,'kodiran.txt'); reset(f);
assign(g,'dekodiran.txt'); rewrite(g);
while not eof(f) do
begin
while not eoln(f) do
begin
read(f,ch);
ch:=pred(ch);
write(g,ch)
end;
readln(f); writeln(g)
end;
close(f); close(g)
end.
Ako je sada,na primer,plain.txt:
Clear fruit nectar. Produced from concentrated sour cherry and apple juice.
Fruit contents: minimum 52%.
Ingredients: concentrated sour cherry and apple juice, water, sugar and citric acid.
Pasteurized, without preservatives.
EGO
Posle pokretanja kodera se dobija kodirani.txt:
Dmfbs!gsvju!ofdubs/!Qspevdfe!gspn!dpodfousbufe!tpvs!difssz!boe!bqqmf!kvjdf/
Gsvju!dpoufout;!njojnvn!63&/
Johsfejfout;!dpodfousbufe!tpvs!difssz!boe!bqqmf!kvjdf-!xbufs-!tvhbs!boe!djusjd!bdje/
Qbtufvsj{fe-!xjuipvu!qsftfswbujwft/
FHP
Voleo bih da mi neko,kao laiku,objasni kako je uopste moguce da neko dekodira,gore kriptovanu,poruku ako ne zna algoritam (nema kod).
OvErDoSe