[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:04.46,0:00:07.35,Default,,0000,0000,0000,,Pentru mai mult de 400 de ani problema a ramas:
Dialogue: 0,0:00:07.35,0:00:10.07,Default,,0000,0000,0000,,Cum ar putea Alice sa creeze un cod
Dialogue: 0,0:00:10.07,0:00:11.73,Default,,0000,0000,0000,,care sa-i ascunda amprenta,
Dialogue: 0,0:00:11.73,0:00:14.36,Default,,0000,0000,0000,,astfel oprind scurgerea de informatii?
Dialogue: 0,0:00:14.36,0:00:16.47,Default,,0000,0000,0000,,Raspunsul este folosirea aleatoriului.
Dialogue: 0,0:00:17.66,0:00:20.47,Default,,0000,0000,0000,,Imaginati-va ca Alice foloseste un zar cu 26 de fete
Dialogue: 0,0:00:20.47,0:00:23.17,Default,,0000,0000,0000,,ca sa genereze o lista lunga de mutari
Dialogue: 0,0:00:23.17,0:00:25.20,Default,,0000,0000,0000,,si sa o imparta cu Bob
Dialogue: 0,0:00:25.20,0:00:27.78,Default,,0000,0000,0000,,in loc de un cuvant pentru a descifra codul.
Dialogue: 0,0:00:27.78,0:00:29.94,Default,,0000,0000,0000,,Acum, pentru a-si encripta mesajul
Dialogue: 0,0:00:29.94,0:00:32.24,Default,,0000,0000,0000,,Alice foloseste lista cu mutari aleatorii in loc
Dialogue: 0,0:00:32.24,0:00:34.46,Default,,0000,0000,0000,,Este important ca aceasta lista de schimbari
Dialogue: 0,0:00:34.46,0:00:36.74,Default,,0000,0000,0000,,Sa fie la fel de lunga ca si mesajul
Dialogue: 0,0:00:36.74,0:00:38.80,Default,,0000,0000,0000,,pentru a evita orice repetitie
Dialogue: 0,0:00:38.84,0:00:41.25,Default,,0000,0000,0000,,Apoi trimite mesajul lui Bob, folosind aceiasi
Dialogue: 0,0:00:41.25,0:00:43.57,Default,,0000,0000,0000,,lista cu mutari aleatorii care i-a dat-o.
Dialogue: 0,0:00:46.32,0:00:48.44,Default,,0000,0000,0000,,Acum Eve va avea o problema,
Dialogue: 0,0:00:48.44,0:00:50.71,Default,,0000,0000,0000,,pentru ca mesajul encriptat
Dialogue: 0,0:00:50.71,0:00:53.04,Default,,0000,0000,0000,,va avea doua proprietati puternice
Dialogue: 0,0:00:53.04,0:00:57.08,Default,,0000,0000,0000,,1: mutarile nu au niciodata un tipar repetitiv
Dialogue: 0,0:00:59.51,0:01:02.11,Default,,0000,0000,0000,,si 2: mesajul encriptat va avea o
Dialogue: 0,0:01:02.11,0:01:04.27,Default,,0000,0000,0000,,distribuire uniforma a frecventei
Dialogue: 0,0:01:04.27,0:01:06.48,Default,,0000,0000,0000,,pentru ca nu exista nicio diferenta in frecventa
Dialogue: 0,0:01:06.48,0:01:08.58,Default,,0000,0000,0000,,si astfel nicio scurgere, este acum
Dialogue: 0,0:01:08.58,0:01:10.97,Default,,0000,0000,0000,,imposibil pentru Eve sa sparga encriptarea
Dialogue: 0,0:01:13.90,0:01:16.44,Default,,0000,0000,0000,,Aceasta este cea mai puternica
Dialogue: 0,0:01:16.44,0:01:18.31,Default,,0000,0000,0000,,metoda de a encripta mesajele
Dialogue: 0,0:01:18.31,0:01:20.67,Default,,0000,0000,0000,,si a aparut spre sfarsitul secolului al 19-lea.
Dialogue: 0,0:01:20.67,0:01:24.37,Default,,0000,0000,0000,,este cunoscuta ca si "one time pad"
Dialogue: 0,0:01:26.23,0:01:29.29,Default,,0000,0000,0000,,Pentru a vizualiza cat de puternic este acest cod
Dialogue: 0,0:01:29.29,0:01:32.04,Default,,0000,0000,0000,,trebuie sa intelegem "explozia" combinatiilor
Dialogue: 0,0:01:32.04,0:01:34.92,Default,,0000,0000,0000,,care are loc. De exemplu
Dialogue: 0,0:01:34.92,0:01:37.84,Default,,0000,0000,0000,,Codul lui Caesar muta fiecare litera
Dialogue: 0,0:01:37.96,0:01:40.26,Default,,0000,0000,0000,,de acelasi numar de ori,
Dialogue: 0,0:01:40.26,0:01:42.94,Default,,0000,0000,0000,,care era un numar intre 1 si 26
Dialogue: 0,0:01:42.94,0:01:45.33,Default,,0000,0000,0000,,Deci, daca Alice si-ar encripta numele,
Dialogue: 0,0:01:45.33,0:01:48.66,Default,,0000,0000,0000,,ar rezulta in 26 encriptii posibile
Dialogue: 0,0:01:48.66,0:01:50.86,Default,,0000,0000,0000,,ceea ce este un numar mic de posibilitati
Dialogue: 0,0:01:50.86,0:01:53.74,Default,,0000,0000,0000,,si usor de verificat
Dialogue: 0,0:01:55.13,0:01:57.22,Default,,0000,0000,0000,,Comparati asta cu "one time pad"
Dialogue: 0,0:01:57.26,0:01:59.54,Default,,0000,0000,0000,,unde fiecare litera ar fi schimbata
Dialogue: 0,0:01:59.54,0:02:01.76,Default,,0000,0000,0000,,de un numar diferit intre 1 si 26
Dialogue: 0,0:02:01.76,0:02:04.26,Default,,0000,0000,0000,,acum ganditi-va la numarul de encriptari posibile:
Dialogue: 0,0:02:04.26,0:02:08.04,Default,,0000,0000,0000,,ar fi 26 inmultit cu el insusi de 5 ori
Dialogue: 0,0:02:08.04,0:02:10.30,Default,,0000,0000,0000,,care este aproape 12 de milioane
Dialogue: 0,0:02:10.30,0:02:13.24,Default,,0000,0000,0000,,Cateodata este greu sa vizualizam
Dialogue: 0,0:02:13.24,0:02:15.69,Default,,0000,0000,0000,,asa ca trebuie sa ne imaginam
Dialogue: 0,0:02:15.69,0:02:17.59,Default,,0000,0000,0000,,ca si-ar scrie numele pe o singura pagina
Dialogue: 0,0:02:17.59,0:02:20.08,Default,,0000,0000,0000,,si peste ea a pus fiecare encriptare posibila.
Dialogue: 0,0:02:20.08,0:02:23.97,Default,,0000,0000,0000,,Cat de inalta credeti ca va fi?
Dialogue: 0,0:02:23.97,0:02:29.34,Default,,0000,0000,0000,,Cu aproape 12 milioane de combinatii
Dialogue: 0,0:02:29.34,0:02:34.76,Default,,0000,0000,0000,,ar fi enorm; aproape un kilometru inaltime
Dialogue: 0,0:02:34.76,0:02:38.82,Default,,0000,0000,0000,,Cand Alice isi encripteaza numele folosind "one time pad"
Dialogue: 0,0:02:38.82,0:02:41.28,Default,,0000,0000,0000,,este acelasi lucru ca si cum
Dialogue: 0,0:02:41.28,0:02:43.79,Default,,0000,0000,0000,,am alege una dintre aceste pagini la intamplare
Dialogue: 0,0:02:43.79,0:02:46.55,Default,,0000,0000,0000,,Din perspectiva lui Eve fiecare cuvant
Dialogue: 0,0:02:46.55,0:02:48.89,Default,,0000,0000,0000,,encriptat cu 5 litere pe care-l are
Dialogue: 0,0:02:48.89,0:02:51.24,Default,,0000,0000,0000,,este la fel de probabil sa fie
Dialogue: 0,0:02:51.24,0:02:53.44,Default,,0000,0000,0000,,oricare din aceasta gramada
Dialogue: 0,0:02:53.44,99:59:59.100,Default,,0000,0000,0000,,Deci asa se pastreaza secretele fara scurgeri!