Paper 5 Randomized Text Encryption

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InternationalReviewonComputersandSoftware(I.RE.CO.S.),Vol.9,N.2ISSN1828-6003 February2014

RandomizedTextEncryption:aNewDimensioninCryptography

JamshedMemon1,MohdZaidiAbdRozan1,MueenUddin2,AdamuAbubakar3,HarunaChiroma3,DzurllkanianDaud4

AbstractCryptographyreferstoprotectingtransmittedinformationfromunauthorizedinterceptionor tampering,whilecryptanalysis isartofbreakingsuchsecretciphersandreading

information,orperhapsreplacingitwithdifferentinformation.Theresearchhighlightsanew

encryptiontechniquecalledrandomizedtextencryption.Thealgorithmproposedincreasesthe

complexityofcryptanalysttodecrypttheciphertextandrestrictsthemtobreakthesecurityof

encoded

file.

The

proposed

technique

uses

random

numbers

added

to

plaintext

along

with

encryptionkey.Afterapplyingencryptiontechnique,eachtimesameplaintextwillbeconvertedto

differentciphertextprovidedthatencryptionkeyissameordifferent.Twodifferentcharactersare

generatedagainstsinglecharacterofplaintextthatdoublesthesizeofencryptedtext.Decryption

processdoesntrequirerandomnumbersbutonlyneedsencryptionkeytodeciphertheencrypted

text.Consequently,theproposedtechniqueissafetodifferentcryptanalyticattackslikeFrequency

analysis,

Brute-Force,

Linear

and

Differential

Cryptanalysis.

Copyright

2014

Praise

WorthyPrizeS.r.l.-Al lrightsreserved.

Keywords:Cryptography,PrivateKeyEncryption,RandomizedText,Ciphertext,Plaintext

I. IntroductionThe glory of communication seems new but

surroundedbydifferentevolutionaleras,transformationsandtrendsevolvedfortheoptimizationandenhancement

of

communication

styles.

Enormous

approaches

were

adoptedandbecameobsolete from time to time,asnewtechnologicalrevolutionshadsetthecommunication

parametersup-to-date.Thewholephenomenonofinformationexchangesignifiestheimportanceofreliableandunfailingtransportationofdataandinformationfromsourcetodestination.

In this concern of intact data transportation,cryptographic techniques are used for securecommunicationstoprovideefficienttransmissionandreceptionofintactandundamageddata.Duetotheknownweaknessesofinformationsystems,informationhasbeendestroyedandindividualinformationrecords

have

been

released

in

illegal

marketing,

which

alsoincludessimilarharmfuleffects.Duetocasessuchasthese,theprotectionof

informationhasbecomeanincreasinglyimportantissue.Theresearchersareworkingtodraftdifferent

solutionsformakingalltypesofinformationincludingtext,audios,videos,imagesandothermeansmoresecureespeciallywheninformationisbeingtransferredovernetwork.

Encryptionisusedtomakealltypesofdocumentsmoresecureand functionallydifferent from theoriginaldocument,

so

that

it

becomes

really

impossible

for

theintruderstogettheoriginalinformationanduseitfor

illegalpurposes[1]-[27].

Specificencryptionissuesincludetheoriginalcontentsandothersecretdocumentsmadethroughcomputerrelatedfilesandmathematicallyrelatedmessagecharacters[1].

Othertechniquestosecurecontentsofinformation

include

modern

coding

technologies,

which

hasbackground

of

confusion

and

diffusion

theory

isincreasinglybeingusedinpublicnetworksliketheInternetande-businessesandvariousothertechniquestypes

like

authentication,

data

integrity,

andnon-repudiationarebeingdevelopedandused[2].

Moving vast amounts of data quickly and securely across prodigious distances is one of our most pressing needs now days. On the Internet data can be anything;this can be credit card numbers , bank account information, health/social security information, or

personalcommunicationwithsomeoneelse.Dataprotectionhasbecomeanindispensablenecessity

nowadays

[6].

The idea of cryptography is to hide informationfrompeepingeyes.Itisusedtosecuretheprivacyandauthenticationof

data

byaltering

itsinformationcontentstopreventunauthorizeduse.Cryptographyisdividedintotworelatedareasnamelycryptographyandcryptanalysis.Cryptographyisthestudyofsecuring(Encrypting)information,whilecryptanalysisisthestudyofbreaking(Decrypting)thatsecuritytogettheinformation.

Anencryptionsystemtakestheoriginalmessageandakey,whichisarrangedbetweensenderandreceiverinadvance,andcreatesanencodedversionof themessagecalledtheciphertext.Whiledecryptingitisassumedthat

thepersontryingtodecodethemessageknowswhatthe

ManuscriptreceivedandrevisedJanuary2014,acceptedFebruary2014 Copyright2014PraiseWorthyPrizeS.r.l.-Allrightsreserved

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generalprocedureisandislookingattheciphertext.Theonlythingotherpersondoesnothaveisthekey.

Oneofthemajorpurposesofdataencryptionistoencode

data

to

be

sent

in

such

a

way,

that

it

becomesdifficultforanunauthorizedpartytodecodetheinformationwithouthavingaproperkey.Anumberof

methods

have

been

proposed

for

data

security,

since

encryption

has

the

potential

to

offer

high-speed

parallelencryptionofdata[7].Indatasecurity,public-keyencryption

(asymmetric

key

system)

has

an

importantrole,becausethereisnoneedforthekeytobesenttothereceiver[8].Inthesetechniques,thepublickeyisavailabletopublicandthereceiverhasitsownkeyorsecretkey.Thesecurityofapublic-keyencryptionschemeagainstadaptivechosenciphertextattack(CCA2)has

been

demonstrated

by

RackoffandSimon[8].Differentotherpublic-keyencryptiontechniqueshavebeenproposed tosecurelyencryptcontentsofdatatobetransferovercommunicationmediums[9],[10].

Naor

and

Yung

[3]

introduced

and

proposed

ciphertext

security

as

secure

means

for

transferringimportantinformationacrossnetworks.RackoffandSimon [4] provided a stronger notion calledindistinguishabilityunderadaptivechosenciphertextattack(IND-CCA2),whichisequivalenttothenotionofnon-malleability[5].Adaptivechosenciphertextsecurityhassincebecomeastandardnotionforthesecurityof

publickeyencryption.Asignificantnumberofeffortshavebeendevotedby researchers to theconstructionof

public

key

encryption

that

is

secure

against

adaptivechosenciphertextattack.Someoftheresearchoutcomesoftheseeffortswerebasedonnon-interactivezero

knowledgeproofs [5],whichwerenotquitepractical inreal

world

applications.

Even

though

the security

of theencryption techniquecanbe increasedby increasing thenumberofkeysbutthesecurityoftheencryptiontechniqueisstilllimitedbytheissueofkeymanagementandtransmission.Allencryptionalgorithmsarebasedontwogeneralprinciples:(a)Substitution,inwhicheachelementof theplain text (bit,groupofbitsor letters) ismapped into another element of cipher textcorresponding to theplain textand (b)Transposition, inwhichelementsintheplaintextarerearrangedintodifferentordertohidetheoriginalmessageoftext.Oncethemessageisreceived,textisconvertedbacktoplain

text

using

reverse

order

already

known

to

receivingperson/party.

The

fundamental

requirement

is

that

noinformationbelostorsimplytosaythatalloperationsarecompletely reversible.The textencryption technique

presentedinthispaperiscalledrandomizedtextencryptiontechnique.Thecomplexityrequiredtodecryptrestricts

theability

ofcryptanalyst.But

likeotherencryptiontechniques,thistechniquealsodoesntguarantee tobeanunbreakable.Theproposed techniquenotonlyuserandomnumberstoencryptplaintextintodifferentciphertextbutitalsouserandomblocksizeequaltothelengthofkey,whichmakesitdifficultforciphertexttobedecryptedwithoutkeyasbruteforce

needtobeappliedofnotonlyallpossibilitiesbutalsoof

allpossiblelengths.TheproposedrandomizedtextencryptiontechniqueusesanycharacterfromUnicodethatcomprisesof65535differentsymbolsforencryption

purpose,makingitdifficultandtimeconsumingjobtoapplybruteforcetodecryptencryptedtext.

II.

Problem

Background

Datasecurityconcernshaverecentlybecomeveryimportantanditcanbeexpectedthatsecuritywilljoin

performanceandpowerasakeydistinguishingfactor incomputersystems.Thisexpectationhaspromptedseveralmajorindustrialeffortstoprovidetrustedcomputer

platformswhichwouldpreventunauthorizedaccessandmodificationofsensitiveorcopyrightedinformationstoredinthesystem[24].

Encryptionisthemosteffectivewaytoachievedatasecurity.TheprocessofEncryptionhidesthecontentsofamessageinawaythattheoriginalinformationis

recovered

only

through

a

decryption

process.

ThepurposeofEncryption is topreventunauthorizedpartiesfromviewingormodifyingthedata.Encryptionoccurswhendataispassedthroughsomesubstitutetechnique,shiftingtechnique,tablereferencesormathematicaloperations.All thoseprocessesgenerateadifferentformofthatdata.Theunencrypteddataisreferredtoasthe

plaintextand theencrypteddataastheciphertext,whichisrepresentationoftheoriginaldatainadifferentform[11].Lately,informationsecurityhasbecomeveryimportant,especiallyincommunications,computersystems,electroniccommerce,datastorageandothers.Data confidentiality is obtained by utilizing

cryptography, toensure thehighestdegreeofprotectionto

users.

Cryptography

is

one

of

the

trusted

practicalmethodsforperforminginformationsecurity.

Themajorityofmoderncryptographyalgorithmsinvolvecalculations,whichhaveto

becarriedouton

acomputer.Imagineacryptographicsystemwithoutanycryptographiccomputationson thepartof thedecoders,suchthatthedecryptioncanbeaccomplishedbythehumanvisualsystem.Suchsystemcanbeusedwherecomputersorotherdecryptiondevicesarescarceandunavailable.Asfortheencryption,suchsystemalsodoesnotneedcomplexcomputationandassuchcouldbedone

bythesimplestmoderncomputers.Inthelasttwo

decades,

numbers

of

researchers

have

focused

ondevelopingcryptosystems,whichrequirecomparativelylesscomplexcomputation.

With the fast development of Internet, datatransmissionthoughInternetisbecomingmoreandmoreimportant.Encryptionofinformationfromsourcetodestinationplaysanimportantroleasithidesorencryptstheoriginalmessagesothatnooneelsecangetaccesstoinformationorunderstandwhatisbeingsenttoreceiving

person.MosttheinformationsentviaInternetissubjectto

eavesdropping as Internet is public entity andinformationflowacrosstheInternetispronetodata

manipulation

and

theft

[23].

A

lot

of

hackers

Copyright2014PraiseWorthyPrizeS.r.l.-Allrightsreserved InternationalReviewonComputersandSoftware,Vol.9,N.2

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JamshedMemonetal.

continuouslymonitortheInternettraffictolookforusefulinformationlikeemailpasswords,creditcardinformationetc.Thoughmanywebsitesnowensuresecuretransmissionofinformationbetweentwoparties

butevenencryptedinformationispronetodecipherasoncehackergetencryptedinformation,itcanbe

decrypted

by

using

cryptanalysis

which

is

the

study

of

breaking

cipher

text

to

extract

information.

Most

of

theencryptiontechniqueslikeAES,DESuseblockcipherthat

encrypt

plaintext

block

byblockwhichmake

iteasierforcryptanalyststousebruteforceattackasblocksizeisalreadyknowntothemsoprobabilitythatakeywillmatchispossiblemorequickly.

III. RelatedWork

Recently,securityhasbecomeahotresearchtopicfortransferringinformation.Severalencryptiontechniquesandalgorithmshavebeenproposedintheliterature.

Cryptography

is

an

important

and

powerful

tool

forsecurityservices,namelyauthentication,confidentiality,integrity,andnon-repudiation.

Cryptographyhastwodominantapproaches,namelysymmetric-key(secret-key)andasymmetric-key(public-key).Thereareavarietyofsymmetricorasymmetricalgorithmsavailable,suchasDES,AES,IDEA,RSA,andEIGamal[20],[21],[25].

Hybridencryption,whichisalsoknownastheKEMDEMapproach[12],appliesapublickeycryptosystemtoencapsulatethekeyofasymmetriccryptosystem(KEM)and thesymmetriccryptosystem issubsequentlyusedtoconcealdata(DEM).CramerandShoupfirst

generalizedthenotionintheirwork[13],[14].KurosawaandDesmedt[15]laterpresentedamoreefficienthybridencryptionschemebyusingaKEMthatisnotnecessarilyadaptivechosenciphertextsecure.Morerecently,Kiltz[16]improvedontheKurosawaDesmedttechniqueandproposedanewapproachtodesigningadaptivechosenciphertextsecurehybridencryptionschemeswithouta randomoracle.ComparedwithKiltzconcretescheme thatrelieson theDDHassumptionandAE-OT1securesymmetricencryption,modifiedZhengSeberryuhschemeisconceptuallymuchsimplerandreliesonlyontheadaptiveDDHassumption.Moreimportant, this newly modified scheme requires

significantly lesscomputation time thanKiltz.Hofheinzand

Kiltz

[17]

recently

proposed

a

new

public

keyencryptionschemebasedonfactoring.Theirschemerequiresonly roughly twoexponentiations inencryptionandroughlyoneexponentiationindecryption.(Here,roughly twooroneexponentiationmeanstwooronefullexponentiationandadditionalexponentiationswithsmallexponents.).Whilefortheencryptionschemes

basedondiscretelogarithm,DHIES[18]isoneofthemost efficient schemes without random oracle.ComparedwithDHIES,whichreliesontheoracleDiffieHellman(ODH)assumptiontogetherwiththesecurityofsymmetricencryptionandamessage

authentication

code

(MAC),

modified

scheme

relies

on

theadaptiveDDHassumptiononlyandpreservesthecomputationalefficiencyofZhengSeberryuh.However,itisfairtosaythatmodifiedZhengSeberryschemeandDHIESarecomparable,eachhavingitsownprosandconsinpractice.WithDHIES,allthreeassumptionsonsymmetricencryption,MACandODHareresponsible

for

the

security

of

DHIES

and

it

is

relatively

easy

to

select

practical

candidates

to

instantiate

functionsunderlyingtheassumptions.WithmodifiedZhengSeberryscheme,theadaptiveDDHassumptionthatissolelyresponsibleforthesecurityoftheschemeisslightlystrongerthantheODHassumptionrequiredbyDHIES.

IV.

OurContribution

Securityisbecomingoneofthemostimperativechallengesfortransferringinformationsecurelyandrecentlyhasbeenthetopicofutmostimportancefor

research

and

industry.

A

lot

of

research

has

been

goingon

to

develop

strategies

and

techniques

to

securelytransferdatawhileprotectingprivacyatthelevelofindividualrecords[22].We proposed a new algorithm to

preprocess text in order to improve the compression ratioof textual documents, in particular online documents such as web pages on the World Wide Web. The processof randomized text encryption is explained below in flowchart in Fig. 1 to show how an input text file is encrypted and output file is generated thatsto be transferred overInternetorsomeothermedium.The flowchartexplainstheprocessofencryption.Applyingencryption functionusingrandomnumbertechniqueandencryptionkeywill

encrypt

input

file.

The

process

of

encryption

will

beapplied

to

each

character

of

input

file

separately

andappendedintoanarrayandthenwillbestoredintoanoutputfile.Theencryptedoutputfile isasecurefileandcanbe

sent

over

Internet

or

via

any

communicationmedium.

IV.1.RandomizedTextEncryptionAlgorithm

Theproposedtextencryptionalgorithmusescharactersasvariableandallothersymbolslikealphabets,numbersandothersymbolsinASCIIcodeareinterpretedasacharacterandtheircorrespondingASCII

codes

were

used

for

arithmetic

operations

e.g.

ASCIIcodeforAis65,Bis66andCis67.Algorithmtakesfileasan inputandextractsalldatafrom itandstores itintoanarraynamedPlaintext.SizeofarrayisNwhereNwillbeequaltosizeoffile.Lengthofciphertextarraywillbedoublethanthatofplaintextaseachplaintextsymbolisconvertedintotwociphertextsymbols.Acharvariablehasbeendefinedwhichstoresrandomcharactergeneratedeachtimeduringtheloop,pseudorandomfunctionhasbeenusedtominimizetherepetitionofrandomcharacters.Loopwillrunfrom1i.e.firstcharacter inarray tillN,which is theendofarray;eachtimeonecharacterfromarrayisencryptedandstoredintoarrayofciphertextuntiltheendofarrayisachieved.


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InputFile

ApplyingEncryption

Technique

JamshedMemonetal.

whereC1andC2areciphertextcharacters,whicharegoingtogeneratefromKeyK,PlaintextPandrandomnumberR,forexample:Plaintext=5Key=7RandomNumber=3

After

putting

these

values

into

proposed

encryption

algorithm

C1=K+2(P)+R

RandomFunction NoC1=7+2(5)+3=20

AndC2=2(K)+P+RC1=2(7)+5+3=22

UseAppropriate EndofFile

KeyIndex

Yes

OutputFile

Fig.1.RandomizedTextEncryptionFlowChart

Aftertheendofloopsciphertextisstoredintoanotherfileandcanbeusedforcommunicationpurposes.The

proposedalgorithmisdepictedinTableI.

TABLEIRANDOMIZEDTEXTENCRYPTIONALGORITHM

IntegernumIntegern

CharPlaintext[n]CharCiphertext[n*2]

CharrandIntegerm=KeySize

Encrypt(Key[m])LoopI=1tonm=I%m1

Ifn=0n=m1

Rand=random()

ResultingciphertextisC1=20andC2=22.

IV.3.RandomizedTextDecryptionAlgorithm

The

second

part

of

paper

focuses

on

the

decryptionprocess,inwhichencryptedfilewillbedecryptedbyapplyingproposeddecryptedalgorithmtogettheoriginalfile.TheprocessofdecryptionisexplainedinflowchartinFig.2.

Theencryptedfilegoesthroughthedecryptionprocesswheredecryptionfunctionusesdecryptionkeystodecryptthefile.Eachcharacterofinputfilegoesthrough thedecryptionprocessseparatelyandappendedintoanarray.Once it isEndof inputfilearrayandthenwillbestoredintoanoutputfile,whichcanbereadbyreceivingperson.

Input

File

ApplyDecryption

Technique

GenerateKey

Ciphertext[num]=key[m]+(2*plaintext[I])+rand

Ciphertext [num+1] = (2 * key[m]) + plaintext [I] + randNum+=2EndofLoop

Index No

AppendCiphertext[]intoCipheredFile

IV.2.WorkingofProposedEncryptionAlgorithm

ForanyencryptionPlainTextPandKeyKisneededtogenerateaCipherTextC.Butforour

proposedtechniquePlaintextP,KeyKandRandomNumberR,areneeded togenerateCipherText1C1andCipherText2C2.EncryptionCalculationforC1andC2C1=K+2(P)+RC2=2(K)+P+R

Decipher

Text EndofFile

Yes

OutputFile

Fig.2.RandomizedTextDecryptionFlowChart


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JamshedMemonetal.

Thedecryptionprocessisreverseofencryptionprocess.Sizeofplaintextarrayishalfofciphertextarrayasciphertextwillbedouble thesizeofplain textduringencryption process. Decryption algorithm takesencrypted fileasan inputandextractsalldata from fileandstores it intoanarraynamedciphertext.Thesizeof

array

will

be

N

where

N

is

equal

to

the

size

of

encrypted

file.Contrary toencryptionprocess randomcharacter isnotneededduringdecryptionprocess.Loopwillrunfrom1 i.e.firstcharacterinarraytillN,whichisendofarray;each time twocharactersfromarraywillbe takenandwillgothroughdecryptionprocessandconverted

backintosingleplaintextcharacter,thewholeprocesswillberepeateduntiltheendofarray.Afterendofloops,

plain textwillbe stored into file,which is readableandoriginalmessagecanberead.

TABLEIIRANDOMIZEDDECRYPTIONALGORITHM

Integernum

IntegernCharCiphertext[n]CharPlaintext[n/2]

Integerm=KeySizeDecrypt(Key[m])

Loopi=1tonm=i%m1

ifn=0n=m-1

Plaintext[i]=(Ciphertext[num]-key[m])(Ciphertext[num+1]-(2*key[m]))

num+=2EndofLoop

AppendPlaintext[]intoPlainFile

IV.4.

Working

of

Proposed

Decryption

Algorithm

C1=K+2(P)+RC2=2(K)+P+R

AsafterapplyingencryptionalgorithmwewillgetC1andC2,inthesamewaydecryptionwillbecalculatedfromencryption:

2(P)+R=C1K

TodecryptthefileweneedtohavejustKeyK,whichisunknownso,Kwillbemovedtoothersideandwillbe

subtracted

from

C1:

P+R=C22K

2(K)willbemovedtoothersideandwillbesubtractedfromC2,nowwewillhave:Equation1: 2(P)+R=C1 KEquation2: P -+R=C2+2K

Bychanging thesignofequation2,R i.e.Randomnumberwillbecanceledduetooppositesign,oneKandonePwillalsobecanceledandwewillgetresultingformulagivenbelow.

P=

(C1

K)

(C2

2K)

Letsuppose:

Plaintext=5Key=7RandomNumber=3

Put

these

values

into

formula:

C1=K+2(P)+RC1=7+2(5)+3=20

and:C2=2(K)+P+R

C1=2(7)+5+3=22

ResultingciphertextisC1=20andC2=22.Nowputthesevaluesintodecryptionformulaitwill

generatesameplaintext,whichwasencrypted.

Decryption

Formula:

P=(C1K)(C22K)

where:C1=20,C2=22andK=7

P=(207)(222(7))=5

Sofive(5)istheplainencryptedtext,whichwasdecryptedbackafterapplyingdecryptiontechnique.

V. Experiments

TwodifferentfilescontainingmessagesATTACKATDAWN

and

0123456789

respectively

were

encryptedanddecryptedtwicebyusingthesamekeytoprovethatencryptiontechniqueworkonbothcharactersandnumbers.Itwasalsoprovedthatdifferentciphertextisgeneratedevenafterweusesamekeytwiceonsame

plaintextbyapplyingtheproposedencryptiontechnique.

V.1. Experiment1:EncryptionofPlainTextFile

Initiallytheencryptionwasappliedonaplaintextfilecontainingonlytext.Theresultsgeneratedare:

Plain

Text:ATTACKATDAWNKey:asdfCipherText:Ff!@l|Ej+If6gB5B-8X9^dn#H

Eachcharacterhasbeenconvertedintotwociphertextcharacters.TableIIIandTableIVshowtheconversionofeachcharacterintotwociphertextcharacters.Thetablesalsoshowencryptionkeyandrandomnumberusedforencryptingeachcharacterinthetextfile.

Inordertoprovethatproposedalgorithmgeneratesdifferentciphertexteachtime,samefilewasencryptedagainusingthesamekey.TableIVshowsthathoweachcharacterwasencryptedusing thesamekey.ComparingTablesIIIandIV,itwasanalyzedthatplaintextandkey

aresamebutciphertextisdifferentinbothtables.


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PlainText Keyan om

JamshedMemonetal.

Itisbecauseofdifferentrandomnumbergeneratedeach time thatcreatedifferentciphertexteven ifweusesamekey.

This

processimproves

thesecurityofplain

textfilebeingencrypted.

TABLEIII

TEXTENCRYPTION1

TABLEVTEXTDECRYPTIONFROMTABLEIII

CipherCipherText1Text2

Key

Plain

Text

F f a A! @ s TL | d TE J f A

+ I a C

PlainText KeyRandom

Number

CipherText1

CipherText2

F s K 6 d SPACE

A a C F fT s ! @T d ` l |A f ] E jC a D + IK s ] f

SPACE d N 6A f Z B gT a , 5 B

SPACE s -D d L 8 XA f Q 9 ^W a U d N

N s # H

TABLEIVTEXTENCRYPTION2

B G f A5 B a T - s SPACE8 X d D9 ^ f AD N a W# H s N

TABLEVITEXTDECRYPTIONFROMTABLEIV

CipherCipherText1Text2

Key

Plain

Text

SPACE

@

a

A

K s T" 2 d T7 \ f A> \ a C

PlainText KeyRandom

Number

CipherText1

CipherText2

E s K ( d SPACE

A a = SPACE @T s P k T d " 2A f O 7 \C a W > \K s \ e

SPACE d @ (A f K 3 XT a W ` m

SPACE s . 4D d P \E(3X`M4


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Key:israCipherText:5.p!a+1o%a'Q!R*

JamshedMemonetal.

theoriginalplaintextfile,butitshowstremendoussecuritywhenappliedagainsttheseattacks.

Plain Cipher

TABLEVIIINUMERICALENCRYPTION2

NumberText1CipherText2

Thedescriptionaboutthesecurityachievedbyproposedencryptionagainstdifferentattacksisexplainedbelow.

0

i

3

5

1 s Y . p2 r K ! a3 a 4 i % +5 S T 1 o6 R G % a7 A X ' Q8 I H ! R9 S *

V.4. Experiment2:DecryptionofPlaintextFile

Duringdecryptionprocessencryptedfileswereconvertedbackintoplaintextusingsamekeyeven

though

the

cipher

text

in

both

files

were

different

fromeachother.

DecryptionFile1CipherText:'A'-!V>.j"L s 5

. J r 6" L a 7


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JamshedMemonetal.

In case of Randomized Text Encryption acryptanalysiswillnotaffectthesecurityofrandomizedtextencryptionnomattercryptanalysthavepreviouslycipheredaplaintextasciphertextisextremelyrandomeachtimeandthereispracticallynochancethatsameciphertextwillberepeated.

IV.4.

DifferentialCryptanalysis

Differentialcryptanalysisisusuallyachosenplaintextattack,meaningthattheattackermustbeabletoobtainencryptedciphertextsforsomesetofplaintextsofhischoosing.Thereare,however,extensionsthatwouldallowaknownplaintextorevenaCiphertext-onlyattack.

Thebasicmethodusespairsofplaintext

relatedbyaconstantdifference;differencecanbedefinedinseveralways,buttheXclusiveOR(XOR)operationisusual.Theattacker thencomputes thedifferencesof thecorrespondingciphertexts,hopingtodetectstatistical

patterns

in

their

distribution.

In

the

basic

attack,

oneparticular

ciphertext

difference

is

expected

to

beespeciallyfrequent;inthisway,theciphercanbedistinguishedfromrandom.

Moresophisticatedvariationsallowthekeytoberecoveredfasterthanexhaustivesearch.Itisverydifficulttoobtainsecretkeythroughdifferentialcryptanalysisbecauseevennochangeinkeyproduceshugedifferenceinciphertext.Ciphertextisabsolutelyrandomandifweassumethatcryptanalysthas

previouslycipheredplaintextand thekey throughwhichitwasciphereditisevenverydifficultforacryptanalysttoknowthatwhethernewciphertextisencryptedwith

samekeyanditissameplaintext.

VII. Conclusion

RandomizedTextEncryptionwasappliedonamessageATTACKATDAWNtwicetoprovethatdifferentciphertextisgeneratedwhensamemessageisencryptedusingsamekey.Aclearadvantageofthistechniqueoverotherexistingonesisthatitgeneratesdifferent

ciphertexteach

time

no

matter

we

apply

samekey,thisisachievedbyapplyingrandomnumbersinencryptionalongwithsymmetrickey.

While indecryptiononejustneed thesymmetrickey

to

decrypt

the

cipher

text.

Another

advantage

of

thistechnique is thatKeysize isnot fixedandsoblocksizeoftexttobeencryptedisalsonotfixed.Thismakesciphertextmoresecuretobrute-forcekindofattacks

because

cryptanalyst

have

toapplyall

keys

withallpossiblecombinationsofallsizes.

Ifwelookattherunningtimeofthealgorithmitislineari.e.O(n)(BigOofn).Itiscomputedthroughanalysisofalgorithm.AlgorithmislinearbecausethereisonlyoneloopinthealgorithmcostsO(n)andallotherstatements

arewithout

loops

costsO(1).

As

lengthofrandomnumbersisfiniteincomputerthatswhyalgorithmislinearandcostsO(n),thisiscomparativelymuchbetterthanmanyalgorithms.

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AuthorsInformation1Department of Information

Systems,

Faculty

of

Computing,

Dr.AdamuAbubakarisaPostdoctoralFellowinInformationSystemdepartmentatInternationalIslamicUniversityMalaysia.HereceivedhisPhDinInformationTechnologyfromInternationalIslamicUniversityMalaysia.HiscurrentresearchinterestisonRemoteTimingAttacks.

Haruna

Chiromis

a

PhD

Student

in

ArtificialIntelligence

department

at

University

ofMalaya.HereceivedhisMScinBayeroUniversityKanoNigeria.HiscurrentresearchinterestisonNeuralNetworks.

DzurllkanianDaudiscurrentlyAssociateprofessorinFacultyofGeoInformationandRealEstate.Mr.Dauddidhisbachelorsinpropertymanagement fromHerriot-WattUniversity,UnitedKingdomandmastersincomputerSciencefromUniversitiTeknologi

Malaysia.

His

Research

interest

includesdatabasemanagementandmodernizationofrealUniversitiTeknologi Malaysia.

2,

3KulliahofInformation

Communication

Technology,InternationalIslamicUniversity,Malaysia.

4FacultyofGeoInformationandRealEstate,UniversitiTeknologiMalaysia.

JamshedMemonisaPhD(InformationSystems) student at UniversitiTeknologiMalaysia.Mr.MemonhasreceivedhisBScandMScinComputerSciencefromIsraUniversityPakistan.HissecondmastersisinComputerSystemsandNetworkingfromUniversityof

Greenwich,Londonin.Mr.Memonisauthorofover10 internationalresearchpublications.HisresearchinterestsincludeInformationSecurityandGreenIT.Hehasover6yearsofindustryexperienceatvariouslevels.

AbdRozanMohdZaidi(Dr.)hasreceivedhisB.Sc.(Hons.)inPhysics&Compw.Ed.,andM.Sc.ITfromUniversitiTeknologiMalaysia(UTM),Malaysia.HehasreceivedaDoctorateofEngineering (D.Eng) in InformationScience& Control Engineering from NagaokaUniversityofTechnology,Japan.HisresearchinterestsareITProjectManagement,Profiling

and Data Mining utilizing Multivariate Approach andTechnopreneurship.HeholdsaRadioAmateurLicence,withcallsign9W2DZD.

Dr.

Mueen

Uddin

is

Senior

Lecturer

at

AsiaPacificUniversityKLMalaysia.HehashisPhDfromUniversitiTeknologiMalaysiaUTMin2012.HisresearchinterestsincludeGreenIT,EnergyEfficientdatacenters,GreenMetrics,GlobalWarmingEffects,Virtualization,CloudComputing.Dr.MueenhasBS&MSinComputerSciencefromIsraUniversityPakistan

withspecializationinInformationNetworks.Dr.Mueenhaspublishedmorethan25internationalJournalPapersinindexedandreputedjournals.

estate.


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Paper 5 Randomized Text Encryption