MELJUN CORTES CRYPTOGRAPHY Elements Lectures

8/17/2019 MELJUN CORTES CRYPTOGRAPHY Elements Lectures

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The Elements of

Cryptography

(March 30, 2016)

© Abdou Illia – Spring 2016


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2

Learning Objectives

Discuss Crp!ograph "#r$inolog

Discuss S$$#!ric %# &ncrp!ion

Discuss As$$#!ric %# &ncrp!ion

Dis!inguish b#!'##n ashing and &ncrp!ion


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3

Cryptography?

"radi!ionall, cryptography r##rs !o

"h# prac!ic# and !h# s!ud o #ncrp!ion

"ransor$ing inor$a!ion in ord#r !o pr#*#n!unau!hori+#d p#opl# !o r#ad i!

"oda, cryptography go#s b#ond#ncrp!ion-d#crp!ion !o includ#

"#chni.u#s or $a/ing sur# !ha! #ncrp!#d$#ssag#s ar# no! $odii#d #n rou!#

"#chni.u#s or s#cur#id#n!iica!ion-au!h#n!ica!ion o co$$unica!ion

par!n#rs


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4

Your knowledge about Cryptography

1) hich o !h# ollo'ing do crp!ographicss!#$s pro!#c!

a) Da!a s!or#d on local s!orag# $#dia (li/# hard dri*#s) ro$acc#ss b unau!hori+#d us#rs

b) Da!a b#ing !rans$i!!#d ro$ poin! A !o poin! in a n#!'or/

c) o!h a and b

45748hh9:;(


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5


2) hich o !h# ollo'ing s#curi! issu#s isaddr#ss#d b crp!ographic ss!#$s

a) Conid#n!iali!= i# pro!#c!ion agains! #a*#sdropping

b) Au!h#n!ica!ion= i# assuranc# par!i#s in*ol*#d in aco$$unica!ion ar# 'ho !h# clai$ !o b#

c) M#ssag# in!#gri!= i# assuranc# !ha! $#ssag#s ar# no!al!#r#d #n rou!#

d) A*ailabili!= i# $a/ing sur# !ha! co$$unica!ion ss!#$sar# no! shu! do'n b in!rud#rs

#) All o !h# abo*#


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6

asic Terminology !

>#!'or/

?lain!#@!#lloB

Ciph#r!#@! 11011101B

Ciph#r!#@! 11011101B?lain!#@!#lloB

D#crp!ion Algori!h$

In!#rc#p!or

?ar! A

?ar!

Plaintext: original $#ssag# !o b# s#n! Could b# !#@!, audio, i$ag#, #!c

Encryption/Decryption Algorithm: $a!h#$a!ical !ool (so!'ar#) us#d !o#ncrp! or d#crp!

Key: A s!ring o bits us#d b !o #ncrp! !h# plain!#@! or d#crp! !h# ciph#r!#@!

Ciphertext: #ncrp!#d $#ssag# oo/s li/# a rando$ s!r#a$ o bi!s

D#crp!ion

/#

&ncrp!ion Algori!h$

&ncrp!ion/#

HelloHello


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asic Terminology "

&ncrp!ionE Con*#r!ing plain!#@! in!o ciph#r!#@! using algori!h$s and /#s

"h# si+# o !h# ciph#r!#@! is propor!ional !o !h# si+# o !h# plain!#@!

Ciph#r!#@! is r#*#rsibl# !o plain!#@!

S$$#!ric %# &ncrp!ionE

Sa$# /# is us#d bo!h or #ncrp!ion and d#crp!ion %#s ar# usuall id#n!ical or !ri*iall id#n!ical:

As$$#!ric %# &ncrp!ionE Also call#d ?ublic-?ri*a!# %# &ncrp!ion

"'o di#r#n! /#s ar# us#dE on# or #ncrp!ion, on# or d#crp!ion

?ar! A ?ar!

?ar! A

?ar!

: "ri*iall id#n!ical $#ans si$pl# !ransor$a!ion could l#ad ro$ on# /# !o !h# ano!h#r

Fnlin# &ncrp!E h!!pE--'''l#@crp!co$-l#@crp!r##h!$l G

http://www.flexcrypt.com/flexcryptfree.htmlhttps://www.tools4noobs.com/online_tools/http://www.flexcrypt.com/flexcryptfree.html


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!


3) as#d on ho' s$$#!ric #ncrp!ion ss!#$s'or/, 'hich o !h# ollo'ing is !h# 'ors! !hing!o happ#n

a) An a!!ac/#r g#!s a cop o !h# #ncrp!ion and d#crp!ionalgori!h$s

b) An a!!ac/#r g#!s !h# d#crp!ion /#

c) a and b ar# #.uall da$aging

H) hich o !h# ollo'ing pr#s#n!s $or# chall#ng#or #@changing /#s b#!'##n par!n#rsa) As$$#!ric #ncrp!ion

b) S$$#!ric #ncrp!ion

c) A and b ar# #.uall chall#nging


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"

E#haustive search and $ey length

Key #ength in bits $%mber o& possible 'eys (2'ey length in bits)

1 2

2 H

H 16

J 286

16 68836

86 K208K8;H03K;2K;00

112 81;22;6J8J83HJ30000000000000000000 or 81;23&33

16J 3KH1HH&80

286 118K;2&KK

812 13H0J&18H

A!!ac/#r could us# !h# righ! algori!h$ and do an #@haus!i*# s#arch (i#!r all possibl# /#s) in ord#r !o d#crp! !h# ciph#r!#@!

Mos! a!!ac/s r#.uir# !h# cap!ur# o larg# a$oun! o ciph#r!#@!

&*#r addi!ional bi! in !h# l#ng!h o !h# /# doubl#s !h# s#arch !i$#

&*#r addi!ional bi! in !h# l#ng!h o !h# /# doubl#s !h# r#.uir#$#n!s in!#r$s o $ini$u$ proc#ssorLs sp##d !o crac/ !h# /#


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*+


H) I ou incr#as# !h# /# l#ng!h ro$ 86 bi!s !o 66bi!s o' $uch $or# /# co$bina!ions ana!!ac/#r 'ho cap!ur#s #nough ciph#r!#@! 'ill ha*#

!o !r in ord#r !o d#ciph#r !h# cap!ur#d ciph#r!#@!using !h# appropria!# algori!h$

8) Assu$ing !ha! i! !a/#s K das !o !r all possibl#co$bina!ions o a 86 bi! /#, ho' $uch !i$# i!'ould !a/# !o !r all possibl# co$bina!ions 'h#n!h# /# l#ng!h is incr#as#d !o 8J bi!s


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**

%eak vs& 'trong $eys

S$$#!ric %# &ncrp!ion suall or pri*a!# o cus!o$#r #Nbusin#ss

%#s O 100Nbi! long ar# consid#r#d '#a/ !oda

%#s *++,bit long or more ar# consid#r#d s!rong !oda

As$$#!ric %# &ncrp!ion suall us#d or 2 #Nco$$#rc#

%# pairs $us! b# $uch long#r (812 bi! and $or#) b#caus# o!h# disas!rous cons#.u#nc#s o br#a/ing !h# d#crp!ion /#

Key #engthin bits

$%mber o& possible 'eys (2'ey length in bits) -ype o& comm%nication

1 21 P 2

2 22 P H

16 216 P 68836

86 286 P K208K8;H03K;2K;00 ?ri*a!#, s$$#!ric, '#a/ as$$#!ric (#g D&S)

100 2100 P ?ri*a!#, s$$#!ric

112 2112 P 81;22;6J8J83HJ30000000000000000000 or 81;23&33 usin#ss, as$$#!ric (#g 112Nbi! D&S)

16J 3KH1HH&80 usin#ss, as$$#!ric (#g 3D&S)

286 118K;2&KK usin#ss, as$$#!ric (#g A&S)

812 13H0J&18H usin#ss, as$$#!ric (#g QSA)


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*2


6) Mos! a!!ac/s r#.uir# !h# cap!ur# o larg#a$oun! o ciph#r!#@!, 'hich can !a/# ac#r!ain a$oun! o !i$# #sid# using s!rong

/#s 'ha! #ls# can b# don# !o $a/# i!hard#r !o crac/ !h# /#


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'ymmetric $ey Encryption


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*4

'ymmetric $ey Encryption methods "'o ca!#gori#s o $#!hods

S!r#a$ ciph#rE algori!h$ op#ra!#s on indi*idual bi!s (or b!#s)= on# a! a !i$#

loc/ ciph#rE op#ra!#s on i@#dNl#ng!h groups o bi!s call#d blocks

Fnl a #' s$$#!ric $#!hods ar# us#d !oda

.ethos 0ear appro1e Comments

Da!a &ncrp!ion S!andard N D&S 1;KK 1;;JE &l#c!ronic Rron!i#r Rounda!ionLs D##pCrac/ br#a/s a D&S /# in 86 hours

D&SNCiph#r loc/ Chaining

"ripl# D&S – "D&S or 3D&S 1;;;

Ad*anc#d &ncrp!ion S!andard – A&S 2001 I!s *#rsions a$ong !h# $os! us#d !oda

ther symmetric encryption methos

ID&A (In!#rna!ional Da!a &ncrp!ion Algori!h$), QC8 (Qi*#s! Ciph#r 8), CAS" (Carlisl# Ada$s S!aord"a*ar#s), lo'ish


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*5

(ata Encryption 'tandard )(E'*

D&S &ncrp!ion?roc#ss

6HNi! Ciph#r!#@!loc/

6HNi! D&S S$$#!ric %#(86 bi!s J r#dundan! bi!s)6HNi! ?lain!#@!

loc/

D&S is a bloc/ #ncrp!ion $#!hod, i# us#s bloc/ ciph#r

D&S us#s a 6H bi! /#= ac!uall 86 bi!s J bi!s co$pu!abl#ro$ !h# o!h#r 86 bi!s

?robl#$E sa$# inpu! plain!#@! gi*#s sa$# ou!pu! ciph#r!#@!


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(E'+Cipher lock Chaining

Rirs!6HNi! ?lain!#@! loc/


S#cond6HNi! ?lain!#@! loc/

Rirs!6HNi! Ciph#r!#@! loc/

Ini!iali+a!ion#c!or (I)


S#cond6HNi! Ciph#r!#@! loc/

D&S %#

D&S %#

D&SNCC us#s ciph#r!#@! ro$ pr#*ious bloc/ as inpu!$a/ing d#crp!ion b a!!ac/#rs #*#n hard#r

An 6HNbi! ini!iali+a!ion *#c!or is us#d or irs! bloc/


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*

Triple (E' ),(E'*

ener ecei1er

&ncrp!s original plain!#@! 'i!h !h#1s! /#

D#crp!s ciph#r!#@! 'i!h!h# 3d /#

D#crp!s ou!pu! o irs!s!#p 'i!h !h# 2nd /#

&ncrp!s ou!pu! o !h#irs! s!#p 'i!h !h# 2nd /#

&ncrp!s ou!pu! o s#conds!#p 'i!h !h# 3d /#= gi*#s!h# ciph#r!#@! !o b# s#n!

D#crp!s ou!pu! o s#conds!#p 'i!h !h# 1s! /#= gi*#s!h# original plain!#@!

*6!,it Encryption ith -hree 56,it Keys

*st

2n

3r

3r

2n

*st


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*!

Triple (E' ),(E'*

ener ecei1er

&ncrp!s plain!#@! 'i!h !h#1s! /#

D#crp!s ciph#r!#@! 'i!h!h# 1s! /#

D#crp!s ou!pu! 'i!h !h#

2nd /#

&ncrp!s ou!pu! 'i!h !h#

2nd /#

&ncrp!s ou!pu! 'i!h !h#1s! /#

D#crp!s ou!pu! 'i!h !h#1s! /#

**2,it Encryption 7ith -o 56,it Keys

*st

2n

*st

*st

2n

*st


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*"


K) as#d on !h# 'a D&S and 3D&S'or/, 'hich o !h# ollo'ing is !ru#a) 3D&S r#.uir#s $or# proc#ssing !i$# !han D&S

b) Co$par#d 3D&S, D&S r#.uir#s $or# QAM

c) o!h a and b

J) Ti*#n !h# incr#asing us# o handNh#ld

d#*ic#s, 3D&S 'ill b# $or# prac!ical!han D&S

a) "ru#

b) Rals#

http://en.wikipedia.org/wiki/Image:Mobile_handheld_device.jpg


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2+

-dvanced Encryption 'tandard + -E'

D#*#lop#d b !'o #lgian crp!ograph#rs, Uoan Da#$#nand inc#n! QiV$#n, and sub$i!!#d !o !h# A&S s#l#c!ionproc#ss und#r !h# na$# WQiVnda#lW, a por!$an!#au o !h#na$#s o !h# in*#n!ors

F#rs /# l#ng!hs o 12J bi!, 1;2 bi!, and 286 bi!

&ici#n! in !#r$s o proc#ssing po'#r and QAMr#.uir#$#n!s co$par#d !o 3D&S

Can b# us#d on a 'id# *ari#! o d#*ic#s including C#llular phon#s ?DAs &!c


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2*

(E'. ,(E'. and -E'

DE

86

#a/

Mod#ra!#

Mod#ra!#

3DE

112 or 16J

S!rong

igh

igh

AE

12J, 1;2, 286

S!rong

Mod#s!

Mod#s!

%# #ng!h (bi!s)

%# S!r#ng!h

?roc#ssingQ#.uir#$#n!s

QAM Q#.uir#$#n!s


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Encryption -lgorithms /sed by 0'

Operating 'ystems

Operating SystemDefault Algorithm Other Algorithms

%indows "111 (E'2 )none*

%indows 23 4T0 (E'2 ,(E'

%indows 23 '3! -E' ,(E'. (E'2

%indows 'erver "11, -E' ,(E'. (E'2

%indows 5ista -E' ,(E'. (E'2%indows 'erver "116 -E' ,(E'. (E'2 )?*


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-symmetric $ey Encryption


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3ublic $ey Encryption 7or confidentiality

?ar! A ?ar!

D#crp! 'i!h?ar! ALs ?ri*a!# %#

&ncrp! 'i!h?ar! ALs ?ublic %#

&ncrp! 'i!h?ar! Ls ?ublic %#

D#crp! 'i!h?ar! Ls ?ri*a!# %#

&ncrp!#dM#ssag#

&ncrp!#dM#ssag#

&ach ?ar! us#s o!h#r par!Ls public /# or #ncrp!ion

&ach ?ar! us#s o'n pri*a!# /# or d#crp!ion

>o n##d !o #@chang# pri*a!# /#, bu! /# n##ds !o b# *#rs!rong (812 bi!)


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3ublic $ey Encryption methods

As$$#!ric #ncrp!ion $#!hods ar# us#d bo!h or &ncrp!ion in ord#r !o pro*id# conid#n!iali!

Digi!al signa!ur# in ord#r !o pro*id# par!n#rsL au!h#n!ica!ion

.ethos 0ear propose CommentsA b Qon i*#s!, Adi ha$ir, and#onard Adl#$an

1;KK 1;;8E Rirs! a!!ac/ in lab condi!ions 'as r#por!#d

&llip!ic Cur*# Crp!oss!#$ N ECC 1;J8 #co$ing 'id#l us#d

ther symmetric encryption methos:

Di##N#ll$an, &lNTa$al


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asic Terminology ,

ashingE Ma!h#$a!ical proc#ss or con*#r!ing inpu!s in!o i@#dNl#ng!h ou!pu!s

ash unc!ionE Algori!h$ !ha! do#s !h# hashing s#s an inpu! a shar#d s#cr#! or

pass'ord &@a$pl#E MD8, S#cur# ash Algori!h$

ashE Ri@#dNl#ng!h ou!pu! o !h# hashing


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2

Encryption 5ersus 8ashing

Encryption

s#s a /# as aninpu! !o an#ncrp!ion $#!hod

Fu!pu! is si$ilar inl#ng!h !o inpu!

Q#*#rsibl#= ciph#r!#@!can b# d#crp!#dbac/ !o plain!#@!

s# o %#

#ng!h oQ#sul!

Q#*#rsibili!

8ashing

?ass'ord is usuall add#d!o !#@!= !h# !'o ar#co$bin#d, and !h#

co$bina!ion is hash#d

Fu!pu! is o a i@#dshor! l#ng!h,r#gardl#ss o inpu!

Fn#N'a unc!ion= hashcanno! b# d#Nhash#dB bac/!o !h# original s!ring


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2!

8ashing 9 3ublic $ey for authentication

As$$#!ric %# &ncrp!ion is also us#d or au!h#n!ica!ion

suall us#d along 'i!h hashingCon&ientiality A%thentication

?ublic %#

&ncrp!ion

S#nd#r #ncrp!s 'i!h

receiver’s public key Q#c#i*#r d#crp!s 'i!h !h#receiver’s own private key

S#nd#r (supplican!) #ncrp!s 'i!h

own private key Q#c#i*#r (*#rii#r)d#crp!s 'i!h !h# public key of thetrue party , usuall ob!ain#d ro$ aC#r!iica!# Au!hori!

ashing s#d in MSNCA? or ini!ialau!h#n!ica!ion and in MACs or$#ssag#NbN$#ssag#au!h#n!ica!ion

ashing and ?ublic %# or au!h#n!ica!ion *#r us#d incrp!ographic ss!#$s li/# SS-"S or I?S#c


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2"

Cryptographic 'ystems

?ac/ag#d s#! o crp!ographic coun!#r$#asur#s us#d orpro!#c!ing dialogu#s

&@a$pl#E S#cur# Soc/#! a#r-"ranspor! a#r S#curi! –SS-"S us#d in s#cur#d '#bs#r*ic#

&ach crp!ographic ss!#$ includ#s di#r#n! s#curi!s!andards (algori!h$s, hashing $#!hods, s#curi!para$#!#rs) !ha! co$$ par!n#rs n##ds !o agr##B on

"pical ?roc#ssE andsha/ing s!ag#s

Fngoing co$$unica!ion s!ag#E M#ssag#NbNM#ssag#au!h#n!ica!ion


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3+

Cryptographic 'ystems )cont&*

?ac/ag#d s#! o crp!ographic coun!#r$#asur#s us#d orpro!#c!ing dialogu#s

andsha/ing S!ag# 1EIni!ial >#go!ia!ion o S#curi! ?ara$#!#rs

andsha/ing S!ag# 2EIni!ial Au!h#n!ica!ion

(suall $u!ual)

andsha/ing S!ag# 3E%#ing

(S#cur# #@chang# o /#s and o!h#r s#cr#!s)

Fngoing Co$$unica!ion S!ag#'i!h M#ssag#NbNM#ssag#

Conid#n!iali!, Au!h#n!ica!ion,and M#ssag# In!#gri!

S#r*#r

Cli#n! ?C

"i$#

&ncrp!#d or Conid#n!iali!

?lain!#@!&l#c!ronic Signa!ur#(Au!h#n!ica!ion, In!#gri!)


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3*

0'+C8-3: 8ashing for -uthentication

: Microso!Ls *#rsion o Chall#ng# andsha/# Au!h#n!ica!ion ?ro!ocol

CA? is an au!h#n!ica!ionsch#$# us#d b ?oin! !o ?oin!

?ro!ocol (???) s#r*#rs !o*alida!# !h# id#n!i! o r#$o!#cli#n!s

1) A!#r !h# co$pl#!ion o !h# lin/#s!ablish$#n! phas#, !h# s#r*#r s#nds aWchall#ng#W $#ssag# !o !h# cli#n!

2) "h# cli#n! r#sponds 'i!h a *alu#calcula!#d using a on#N'a hashunc!ion, such as an .D5 or 8A (S#cur# ash Algori!h$)

3) "h# s#r*#r ch#c/s !h# r#spons# agains!i!s o'n calcula!ion o !h# #@p#c!#d hash*alu# I !h# *alu#s $a!ch, !h# s#r*#r

ac/no'l#dg#s !h# au!h#n!ica!ion=o!h#r'is# i! should !#r$ina!# !h#conn#c!ion

H) A! rando$ in!#r*als !h# s#r*#r s#nds an#' chall#ng# !o !h# p##r and r#p#a!ss!#ps 1 !hrough 3

Shar#d s#cr#!


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0essage+by+0essage -uthenticationusing 8ashing and 3ublic $ey"o Cr#a!# !h# Digi!al Signa!ur#E

1 ash !h# plain!#@! !o cr#a!# abri# M#ssag# Dig#s!= !his is>F" !h# Digi!al Signa!ur#

2 Sign (#ncrp!) !h# $#ssag#dig#s! 'i!h !h# s#nd#rLs pri*a!#/# !o cr#a!# !h# Digi!al Signa!ur#

3 "rans$i! !h# plain!#@! digi!alsigna!ur#, #ncrp!#d 'i!h

s$$#!ric /# #ncrp!ion

?lain!#@!

MD

DS

ash

Sign (&ncrp!)'i!h S#nd#rLs?ri*a!# %#

49 Encrypte ith

ession Key

DS ?lain!#@!

S#nd#r Q#c#i*#r

?lain!#@!


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0essage+by+0essage-uthentication )cont&*

"o "#s! !h# Digi!al Signa!ur#

8 ash !h# r#c#i*#d plain!#@!'i!h !h# sa$# hashing algori!h$

!h# s#nd#r us#d "his gi*#s!h# $#ssag# dig#s!

6 D#crp! !h# digi!al signa!ur#'i!h !h# s#nd#rLs public /#

"his also should gi*# !h#

$#ssag# dig#s!

K I !h# !'o $a!ch, !h#$#ssag# is au!h#n!ica!#d

MD

Q#c#i*#d ?lain!#@!

MD

DS

8 6

ash

D#crp! 'i!h"ru# ?ar!Ls?ublic %#

K Ar# !h# #.ual

?lain!#@!

MD

DS

ash

Sign (&ncrp!)'i!h S#nd#rLs?ri*a!# %#


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'ummary ;uestions

S## Xu#s!ions on 0o%r 'nolege Abo%t

CryptographyLs slid#s in !h#s# class no!#s S## Q#adingXu#s!ionCh3doc il# in >o!#sL s#c!ion o

'#b si!# &ncrp!ion &@#rcis#s pos!#d !o !h# cours# '#bsi!#

Documents

MELJUN CORTES CRYPTOGRAPHY Elements Lectures