1
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2
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>> ROB BOWDEN: Jien Rob, u
ejja nikseb qsim.

3
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Mela ftakar mill-spec pset li
aħna qed tmur biex tkun jeħtieġu li tuża l-

4
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funzjoni kripta.

5
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Għall-paġna bniedem, għandna żewġ
hash jiddefinixxu _xopensource.

6
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Ma joqogħdu jinkwetaw dwar għaliex
għandna bżonn li tagħmel dan.

7
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U wkoll hash jinkludu unistd.h.

8
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>> Allura ladarba dan huwa barra mill-mod, ejja
jiksbu l-programm attwali.

9
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L-ewwel ħaġa li għandna bżonn tagħmel huwa li tiżgura
l-utent daħal encrypted valida

10
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password fil-linja tal-kmand.

11
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Ftakar li l-programm huwa suppost
li jitmexxew bħal dot mmejla xquq, u

12
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allura string encrypted.

13
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>> Allura hawnhekk aħna qed verifika biex jiġi żgurat
li argc għal żewġ jekk irridu

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tkompli bil-programm.

15
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Jekk argc mhux tnejn, li tfisser jew
l-utent ma daħħalx kriptat

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password fil-linja tal-kmand, jew
daħal aktar minn sempliċiment il encrypted

17
00:01:02,560 --> 00:01:05,379
password fil-linja tal-kmand, li fiha
każ aħna ma jafu x'għandhom jagħmlu ma 'l-

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linja argumenti kmand.

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>> Mela jekk argc kien tnejn, nistgħu tkompli.

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U hawn, aħna qed tmur biex tiddikjara
varjabbli encrypted.

21
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Li jinsab biss ser alias l-oriġinali
argv1 sabiex matul dan

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programm, aħna ma jkollhomx li hija sejħa argv1,
li mbagħad trid taħseb

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dwar dak li attwalment fisser.

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>> Allura finalment, irridu biex jivvalidaw li
il-password encrypted l-utent

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jiddaħħlu jistgħu jkunu ġew attwalment
password encrypted.

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Per il-paġna bniedem ta 'kripta, l-
password encrypted għandu jkun ta '13

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karattri twil.

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Up hawn, avviż li aħna hash definit
kriptaġġ tul bħala 13.

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Allura aħna qed biss tagħmel ċert li l-
tul sensiela ta 'l encrypted

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password huwa 13.

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>> U jekk mhuwiex, irridu
għall-ħruġ tal-programm.

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Allura ladarba dan huwa barra mill-mod, nistgħu
issa fil-fatt tipprova ssib dak li l-

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password li taw l encrypted
password kien.

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Hawnhekk, irridu li grab l-melħ
mill-password encrypted.

35
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Ftakar, kull l-paġna bniedem, li l-
ewwel żewġ karattri tal kriptat

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spag, bħal hawn -

37
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50ZPJ u l-bqija -

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l-ewwel żewġ karattri jagħtu
us il-melħ li ntuża

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fil-funzjoni kripta.

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>> U hawn, naraw li l-melħ kien ha.

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Allura aħna tixtieq li kopja l-ewwel tnejn
karattri, tul melħ jkunu hash

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definita bħala tnejn.

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Irridu kopja l-ewwel żewġ karattri
fis dan array, melħ.

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Avviż li għandna bżonn tul melħ plus
waħda, peress li aħna għad għandhom bżonn null

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terminatur fl-aħħar ta 'melħ tagħna.

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>> Imbagħad aħna qed tmur biex jiddikjara dan array,
guest, tat-tul max daqs plus

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wieħed, fejn it-tul max huwa hash definit
bħala tmienja, peress li l-password massimu

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huwa tmien karattri fit-tul.

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U aħna qed tmur biex tuża din jtenni
fuq kordi kollha possibbli li jistgħu

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jkun passwords validi.

51
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Allura jekk il-karattri validi fi password
kienu biss, b, u ċ, allura

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aħna se jtenni fuq, b, c,
aa, ba, ca, u l-bqija, sakemm

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irridu jiksbu biex tara cccccccc -

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tmienja c'S.

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>> U jekk aħna ma jistabbilixxi validu
password, allura għandna bżonn li ngħidu li l-

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string encrypted ma kienx
validu li tibda bil.

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Allura issa, aħna jilħqu dan filwaqt li 1 loop.

58
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Avviż li jfisser li huwa
loop infinita.

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>> Avviż hemm ebda stqarrija break
ġewwa ta 'dan loop infinita.

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Hemm biss ritorn dikjarazzjonijiet.

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Allura aħna qatt attwalment jistennew
għall-ħruġ tal loop.

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Aħna biss nistennew għall-ħruġ tal-programm.

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Stajt miżjud din l-istqarrija għall-istampar
Barra minn dan loop għal ftit jistampa

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dak raden attwali tagħna fil
dak li l-password huwa.

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>> Issa, dak li huwa dan loop tagħmel?

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Huwa looping fuq kordi kollha possibbli
li jista 'jkun passwords validi.

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L-ewwel ħaġa aħna qed tmur biex tagħmel hu
tieħu raden attwali tagħna għal dak il-

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password.

69
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Aħna ser nieħdu l-melħ li aħna grabbed minn
-sekwenza encrypted, u aħna

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jmorru għall-kriptaġġ l-raden.

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Dan se tagħtina raden encrypted,
li aħna qed tmur biex iqabblu kontra

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-sekwenza encrypted li l-utent
daħal fil-linja tal-kmand.

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>> Jekk huma l-istess, f'liema każ
string komparabbli se terġa 'lura zero, jekk

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dawn qed l-istess, allura raden kien il-
password li ġġenerat l encrypted

75
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spag, f'liema każ nistgħu jistampaw
li bħala password tagħna u r-ritorn.

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Iżda jekk dawn ma kinux l-istess, li
ifisser raden tagħna kienet żbaljata.

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>> U rridu li jtenni li
l-raden validu li jmiss.

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Allura dak hu li dan waqt li
loop qed tipprova tagħmel.

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Huwa ser jtenni raden tagħna
għall-raden validu li jmiss.

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Avviż li meta ngħidu li
karattru partikolari fil raden tagħna

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laħaq is-simbolu max, li up here
huwa hash definit bħala tilde, peress

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li l-akbar karattru valur ASCII
li utent jista 'jidħol fil-

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keyboard, meta l-karattru jilħaq il-
max simbolu, allura aħna trid tibgħat

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lura lill-simbolu minimu, li
huwa spazju, għal darb'oħra l-ASCII aktar baxx

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simbolu valur li utent jista '
jidħol fil-keyboard.

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>> Allura aħna qed tmur biex ikun stabbilit li
is-simbolu minimu.

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U allura aħna qed tmur biex jmorru
fuq il-karattru li jmiss.

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Allura kif huma guesses tagħna
se jtenni?

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Ukoll, jekk il-karattri huma validi a, b,
u c, allura jekk aħna beda,

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dan ser jtenni li b, dan ser
jtenni li ċ.

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c hija simbolu max tagħna, hekk aħna ser jistabbilixxu
c lura għal, is-simbolu minimu.

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U allura aħna ser jtenni indiċi
għall-karattru li jmiss.

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>> Allura jekk il-raden oriġinali kienet c, li jmiss
karattru se tkun l null

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terminatur.

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Down hawn, avviż li jekk il-karattru
li aħna issa jridu

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inkrement kien il-terminatur null,
allura aħna qed tmur biex tistabbilixxi li l-

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simbolu minimu.

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Allura jekk il-raden kien c, allura tagħna
raden ġdida se tkun aa.

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U jekk raden oriġinali tagħna kienet
cccc, allura raden ġdida tagħna

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se tkun aaaaa.

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>> Allura kull meta aħna jilħqu l-string massimu
ta 'tul partikolari, allura aħna qed

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ser timplimenta l-sekwenza minimu
tat-tul li jmiss, li se

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biss tkun karattri kollha ta '
is-simbolu minimu.

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Issa, dak li huwa dan il-kontroll tagħmel hawn?

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Ukoll, jekk indiċi mċaqlaq mill-tmien
karattru għall-karattru disa -

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hekk aħna żid tmien c bħala
preċedenti tagħna raden -

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allura indiċi huwa ser tiffoka fuq il-
aħħar null terminatur tas raden tagħna

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array, li mhix maħsuba li attwalment
jintużaw password tagħna.

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>> Allura jekk aħna huma ffokati fuq li l-aħħar null
terminatur, allura aħna ma sabu

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password thats validu bl-użu biss tmienja
karattri, li jfisser m'hemm l-ebda

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password valida li encrypts
għall-sekwenza mogħtija.

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U aħna għandna biex jistampaw li, qal
aħna ma setgħetx issib valida

113
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password, u r-ritorn.

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Allura dan loop filwaqt li se jtenni
fuq kordi kollha possibbli.

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>> Jekk issib xi li encrypts l-
string encrypted mistenni, dan ser

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ritorn li password.

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U ma jsibu xejn, allura
huwa ser jerġa, l-istampar li

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ma kienx kapaċi li jsibu xejn.

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Issa, avviż li iterazzjoni fuq kollha
kordi possibbli hija probabbilment se

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jieħu waqt.

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Ejja naraw kif fil-fatt
twil li jieħu.

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>> Ejja jagħmlu xquq.

123
00:07:47,230 --> 00:07:51,050
Well, oops - jgħid undefined
referenza għal kripta.

124
00:07:51,050 --> 00:07:55,330
Mela ftakar, għall-p settijiet spec u
wkoll il-paġna bniedem għal kripta li aħna

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bżonn ir-rabta kripta.

126
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Issa, l-inadempjenza tagħmel kmand
ma taf li inti

127
00:08:01,130 --> 00:08:03,010
tixtieq li tuża dik il-funzjoni.

128
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>> Mela ejja Kopja ta 'din il-kmand klijent
u żid ftit fuq l-aħħar

129
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ta 'dan, jgħaqqdu crypt.

130
00:08:13,300 --> 00:08:14,820
Issa, hija tiġbor.

131
00:08:14,820 --> 00:08:23,880
Mela ejja jimxu xquq fuq mogħti
string encrypted -

132
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hekk Caesar.

133
00:08:25,130 --> 00:08:28,690

134
00:08:28,690 --> 00:08:30,790
Allura li kien pretty fast.

135
00:08:30,790 --> 00:08:33,230
>> Avviż li din ntemm fit-13.

136
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Ukoll, password encrypted Caesar
jiġri li jkun 13.

137
00:08:38,240 --> 00:08:41,650
Mela ejja jippruvaw password ieħor.

138
00:08:41,650 --> 00:08:45,830
Ejja tieħu encrypted Hirschhorn tal
password u jippruvaw qsim dan.

139
00:08:45,830 --> 00:08:51,750

140
00:08:51,750 --> 00:08:55,110
>> Allura avviż konna diġà laħqu
tliet karattri.

141
00:08:55,110 --> 00:08:58,660
U aħna qed iterazzjoni fuq kollha possibbli
kordi tliet karattru.

142
00:08:58,660 --> 00:09:01,420
Dan ifisser li għandna stajt diġà finitura
iterazzjoni fuq waħda kollha possibbli u

143
00:09:01,420 --> 00:09:04,660
żewġ Sekwenzi ta 'karattri.

144
00:09:04,660 --> 00:09:09,180
Issa, jidher qisu dan se
tieħu filwaqt li qabel nilħqu l-

145
00:09:09,180 --> 00:09:10,580
kordi erba 'karattru.

146
00:09:10,580 --> 00:09:14,680
Huwa jista 'jieħu ftit minuti.

147
00:09:14,680 --> 00:09:16,055
>> Hija ma tieħu ftit minuti.

148
00:09:16,055 --> 00:09:18,450
Aħna fuq il-kordi ta 'erba' karattru.

149
00:09:18,450 --> 00:09:22,800
Imma issa, għandna bżonn li jtenni fuq kollha
kordi erba 'karattru possibbli, li

150
00:09:22,800 --> 00:09:26,000
li jista 'jieħu forsi 10 minuti.

151
00:09:26,000 --> 00:09:28,720
U allura meta aħna jilħqu ħames karattru
kordi, għandna bżonn li jtenni fuq kollha

152
00:09:28,720 --> 00:09:31,450
ta 'dawk, li jistgħu
jieħu ftit sigħat.

153
00:09:31,450 --> 00:09:34,080
U għandna bżonn li jtenni fuq kollha possibbli
sitt karattri kordi, li

154
00:09:34,080 --> 00:09:36,560
jista 'jieħu ftit jiem u l-bqija.

155
00:09:36,560 --> 00:09:41,380
>> Għalhekk tista 'tieħu potenzjalment twil ħafna
żmien tirrepeti l fuq kollha possibbli

156
00:09:41,380 --> 00:09:44,850
tmien karattru u inqas kordi.

157
00:09:44,850 --> 00:09:50,600
Allura avviż li dan mhux neċessarjament
algoritmu effiċjenti ħafna għall-konstatazzjoni

158
00:09:50,600 --> 00:09:51,860
password.

159
00:09:51,860 --> 00:09:54,540
Għandek mnejn taħseb li hemm
modi aħjar.

160
00:09:54,540 --> 00:10:02,230
Per eżempju, il ZYX password! 32ab
probabbilment mhix password komuni ħafna,

161
00:10:02,230 --> 00:10:06,440
billi l-password 12345 hija
probabbilment ħafna aktar komuni.

162
00:10:06,440 --> 00:10:13,570
>> Allura mod wieħed ta 'tipprova ssib password
aktar malajr huwa li tfittex biss

163
00:10:13,570 --> 00:10:15,560
fil passwords li huma aktar komuni.

164
00:10:15,560 --> 00:10:20,480
Hekk per eżempju, nistgħu nippruvaw biex taqra kliem
minn dizzjunarju u jippruvaw kollha ta '

165
00:10:20,480 --> 00:10:24,860
dawn il-kliem bħala guesses password tagħna.

166
00:10:24,860 --> 00:10:29,210
Issa, forsi password
ma tkunx dik sempliċi.

167
00:10:29,210 --> 00:10:32,600
Forsi l-utent kien kemmxejn għaqlija
u jippruvaw jpoġġu numru li

168
00:10:32,600 --> 00:10:34,220
l-aħħar ta 'kelma.

169
00:10:34,220 --> 00:10:37,000
>> Allura forsi password tagħhom kien password1.

170
00:10:37,000 --> 00:10:41,520
Allura inti tista 'tipprova iterazzjoni fuq kliem kollha
fid-dizzjunarju ma 'wieħed

171
00:10:41,520 --> 00:10:43,210
mehmuż mat-tmiem ta 'dan.

172
00:10:43,210 --> 00:10:47,360
U allura forsi wara li tagħmel dan, inti ser
tehmeż tnejn sa l-aħħar ta 'dan.

173
00:10:47,360 --> 00:10:50,240
>> Jew forsi l-utent qed tipprova tkun saħansitra
aktar għaqlija, u huma jridu tagħhom

174
00:10:50,240 --> 00:10:54,980
password li tkun "Hacker," iżda dawn qed
ser tissostitwixxi każijiet kollha ta 'e tal

175
00:10:54,980 --> 00:10:56,600
ma threes.

176
00:10:56,600 --> 00:10:58,440
Allura inti tista 'tagħmel dan ukoll.

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Jtenni fuq kollha kliem fid-dizzjunarju
iżda tissostitwixxi karattri li

178
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look like numri ma 'dawk in-numri.

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>> Allura dan il-mod, inti tista 'qabda aktar
passwords li huma pjuttost komuni.

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Iżda fl-aħħar, l-uniku mod inti tista '
jaqbdu passwords kollha huwa li brute

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seħħ jtenni fuq kollha
kordi possibbli.

182
00:11:17,340 --> 00:11:22,100
Għalhekk fl-aħħar, għandek bżonn tagħmel biex jtenni
fuq kordi kollha minn karattru wieħed għal

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00:11:22,100 --> 00:11:28,110
tmien karattri, li jistgħu jieħdu
żmien twil ħafna, iżda inti għandek bżonn tagħmel dan.

184
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>> Jisimni Rob Bowden.

185
00:11:30,024 --> 00:11:31,425
U dan huwa jixxaqqaq.

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