[PPT] - 90 PowerPoint Presentation, free download

SLIDE 1

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SLIDE 2

!
"#
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"#
$%
–

&$ %

SLIDE 3

Plaintext: the original message
!" #$

: '"$ () *+

Ciphertext: the coded message

! #$ : '", *+

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! #$

: '", *+

Cipher: algorithm for transforming plaintext to ciphertext
!

:

. /0 1,2 -. 3 "4 . 56
Key: info used in cipher known only to sender/receiver
&'

: '".7 897 :; < ':.:5 : / => / '"; ": @2 *+ .

SLIDE 4

Encipher (encrypt): converting plaintext to ciphertext
(!)*!

:

. /0 1,2 -. 3 "4
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Decipher (decrypt): recovering plaintext from ciphertext
+*!

:

. # 1,2 -. BC.

SLIDE 5

Cryptography: study of encryption principles/methods
,!

: D; E 5) (=

Cryptanalysis (codebreaking): the study of principles/
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Cryptanalysis (codebreaking): the study of principles/

methods of deciphering ciphertext without knowing key

! -'.

: "( # F> @"0 -. $; E 5) (=

Cryptology: the field of both cryptography and

cryptanalysis

(!/!

: 3(G 5 H # 3)I (=

SLIDE 6

65! 0 :!

/ )5JK "( /

"(
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':. L.$ "( # '"; '".7 .

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/: # 34< F5 M

70

SLIDE 7

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SLIDE 8

!
(!/! (0

(&1

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(!/! (0 (&1

$%
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&$ %

SLIDE 9

@9. # - ':. 0 "# :

:

5< . 56
". ';2 @2 # '"; '".7 M / "(

.

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". ';2 @2 # '"; '".7 M / "(

. Y = EK(X) X = DK(Y)

& PC$ / 0 . 56 / & @2 0 Q7

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& "( R #5 0 - /0 # - 00

.

SLIDE 10

!"

(!)*! (2 3$4 !, 56
%

) Substitution :( : J= 0 J= %

&$ %

) Transposition :( '", )= U0%

3$4 !, (0&' &7
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3$4 !, (0&' &7
L.$ )5JK "(
V4 W> 0 "( :

) 5= "( + )5JK "( (

!" #$ 819 8!
5(0

: E#:+ -. )= # 5(0 "5, .

%

: : '", ':: : /0 /.5+ 5> /0 -. )= BK '", J= /YG6 :5, .

SLIDE 11

#$% &'()

': 1 ;&0

:

"( BC.
'", -. # 1,2 -. BC.
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'", -. # 1,2 -. BC.
': ,.

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. 56 Z)5JK 0
/=5U 0
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M2 '", 1,2

SLIDE 12

#$% &'() *+

$$% , ! &-'. $() *+

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@2 '", 1,2 -. &% "[
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@2 '", 1,2 -. &% "[
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@2 :! -. ((G 85 '", \C. 1,2

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@2 :! -. ((G 85 '", \C. 1,2

@2 $; # 3)I 1,2 -. ((G 85 '", \C. -.

SLIDE 13

&/) 0( +123

".0

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& , 30< 1,2 -. / & - 0 Q7

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SLIDE 14

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"1 /_ 1,2 -. !`< -! 0 ) . 56 - 00

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"1 /_ 1,2 -. !`< -! 0

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SLIDE 15

!
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SLIDE 16

4'5

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SLIDE 17

4'5

+@
: WI 0 WI $%
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+/@
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SLIDE 18

6 4'5 #$%

A?:

Brute Force

ZdI / 5U.%

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1 "(

(

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B -'. A?:
WI 7

(etanos…)

WI Z4 7

(th, nt)

/( M. ".0 WI

(th_, _nt, ___gh)

@0# ; : :5%5 Y

SLIDE 19

725 #$%

C,$ ! '/ ;: B

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SLIDE 20

6 4'5 #$%

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Kasiski : 1 56 -.7 4 0 E - ) e5= 7I / ( ':.:5 "( 5> @: "+ '", -. : & 5. .

'"

: "( 5> 0 .I " 0 ]1 56 # 1 : -0 /()7

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: "( 5> 0 .I " 0 ]1 56 # 1 : -0 /()7 fC0 ':. :5 ",0 D+ .

K: VIGVIGVIGVIGVIG P: THEBOYHASTHEBAG C: OPKWWECIYOPKWIM

SLIDE 21

783

abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz

send another catapult

abcdefghijklmnopqrstuvwxyz

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abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz

rdmc zmnsqds bzszotks r

AD,EF

':. g57 57 /0$ % 57 # M
:5,

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M

25 :5, . & *#d "( .

!"#$

SLIDE 22

79: 4 783

:5, - % 46 : : WI 0 WI

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Plain: Plain: Plain: Plain: a bc d e f g h i j k l m n o p q r s t u v w x y z

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Cipher:

Cipher: Cipher: Cipher: D E F G H I J K L M N O P Q R S T U V W X Y Z A B C

0 , :

Playfair Cipher
Hill Cipher

SLIDE 23

79: 4 783 #$%

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Brute-Force

1 "( :"!

1026 × 4 ! = 26 ⇐

1o

B ': C

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]WI 7 : "+ WI 6.I p @5 .

"!0 " : q

SLIDE 24

79: 4 783 #$%

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&! #$ ;: B

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79:> 783

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Vigenere

SLIDE 26

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Plain: send another catapult

abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz abcdefghijklmnopqrstuvwxyz

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abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz

abcdefghijklmnopqrstuvwxyz

abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz

abcdefghijklmnopqrstuvwxyz

Cipher: ufqf bqqukgs fcudrvov

SLIDE 27

\5G 46 "[ $% =5

:5, .

c #

26 : 26

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PC$ c " .

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:5, .

5(0 # $; D; - 0

Vigenere

:5 ':. @5

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SLIDE 28

! (,'2

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SLIDE 29

(!)*!

:

@5. = Y:5 WI ` = "( WI

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` = "( WI R>9 3G = Y:5 WI '",

+*!

:

` = "( WI R>9 3G = '", WI @5. = '", $; WI

P= SEND ANOTHER CATAPULT

K= hail caeserh ailcaese C= ZEVO CNSLLVY CIECPYDX

SLIDE 30

#$%

$% ]WI 0

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Vigenere

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Kasiski

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1,2 -. '#" /0 "( E.;

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Pad :: * . : One-Time Pad 0 897 "( # ':. :5,

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One-Time Pad 0 897 "( # ':. :5, : .

(!)*!

: Ci = Pi ⊕ ⊕ ⊕ ⊕Ki ⊕ means XOR

+*!

: Pi = Ci ⊕ ⊕ ⊕ ⊕Ki

SLIDE 32

#$% !

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SLIDE 33

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+ B

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SEND* ANOTH ER*CA TAPUL T**** SAETTENRANOP*DTCU**HAL* NOPDTCUENRASAETTHAL

SLIDE 39

783 #$%

Aerial reconnaissance reports enemy reinforcements estimated at battalion strength entering your sector PD Clarke

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SLIDE 40

783 #$%

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783 #$%

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! #$ : '", *+

: '", *+

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: '".7 897 :; < ':.:5 : / => / '"; ": @2 *+ .

:

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: D; E 5) (=

methods of deciphering ciphertext without knowing key

: "( # F> @"0 -. $; E 5) (=

cryptanalysis

: 3(G 5 H # 3)I (=

/ )5JK "( /

':. L.$ "( # '"; '".7 .

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. Y = EK(X) X = DK(Y)

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) Substitution :( : J= 0 J= %

) Transposition :( '", )= U0%

) 5= "( + )5JK "( (

: E#:+ -. )= # 5(0 "5, .

: : '", ':: : /0 /.5+ 5> /0 -. )= BK '", J= /YG6 :5, .

#$% &'()

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M2 '", 1,2

#$% &'() *+

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Brute Force

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(etanos…)

(th, nt)

(th___, ___nt, ___gh)

725 #$%

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6 4'5 #$%

Kasiski : 1 56 -.7 4 0 E - ) e5= 7I / ( ':.:5 "( 5> @: "+ '", -. : & 5. .

: "( 5> 0 .I " 0 ]1 56 # 1 : -0 /()7

: "( 5> 0 .I " 0 ]1 56 # 1 : -0 /()7 fC0 ':. :5 ",0 D+ .

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79: 4 783

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1026 × 4 ! = 26 ⇐

B ': C

]WI 7 : "+ WI 6.I p @5 .

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(th_, _nt, ___gh)