break the code cryptography for beginners

Free ebooks ==> www.Ebook777.comZontents Introduction iv "Crypto"Talk v Samplegrid sheet vii Samplealphabet blanks viii Simple Letter Grouping 2Secretmessages Nos.1-8 The Reverse Trail 1

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Free ebooks ==> www.Ebook777.com

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l^reak the (Zode

7§>uA Johnson

IllustrationsbyLarryDaste

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Tomybeautifulwife,Evelyne— mylove,mypartner,withoutwhoseinsight,beliefand encouragementmycryptocareerwouldnot have happened

To M/Sgt JimmyWest,

who"awakened"metotheexcitementandcomplexitiesofcryptography

Andto thelovingmemoryof Sgt.WilliamE.(Bill)Kelly,my ArmyAirCorps buddy

Fromthejunglestothe desert,we'crypt'throughit all

—

fromcryptography schooltoa lifelong friendship,youmadeita blast, Kel

-About the Autkot

J BudJohnsonserved inWorldWarII asa cryptographer/

joe cryptanalystfortheArmyAir Corps.Theactivitiesof hisand

1997 otheroverseasfieldintelligenceunitsintheinterceptionof

enemycoded messagesandthecaptureofcodesand codeequipment wereimportant contributionstothesuccessful

Normandylandingsofthe Allied invasionforces,inJune1944,

aswellas tothewareffortingeneral.InJune1994,BudJohnson

was honored bytheFrenchgovernmentwithtwo medalsfor his

wartimework

All rightsreservedunderPanAmericanandInternationalCopyrightConventions

PublishedinCanada by General PublishingCompany,Ltd.,30LesmillRoad,

DonMills, Toronto, Ontario.

Publishedin theUnitedKingdomby Constable andCompany,Ltd.

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(Zontents

Introduction iv

"Crypto"Talk v

Samplegrid sheet vii

Samplealphabet blanks viii

Simple Letter Grouping 2Secretmessages Nos.1-8

The Reverse Trail 12Secretmessages Nos.9-16

Secretmessages Nos.17-25

Make Your OwnSecretMessage

Key Word Code 34Secretmessages Nos 26-34

Date Shift Code 46

Secretmessages Nos 35-43

Twisted Path Code 58Secretmessages Nos.44-51

Solutions to the Secret Messages 69

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DINGA RELOT SOFFU NWXYZ

No,it'snot gibberish! Readletterbyletteruntilyoufindaword

—

in this case,ENCODING Keep going andyou'llfindthatthecoded messagereads: Encoding and decodingarelotsoffun(wxyz)

(Thosenonsenselettersattheend—"wxyz"— makethemessageeventrickiertoread!)

You now know one waytodecode — but can you .

EGASS EMDED OCEHT KAERB

It'seasy Just read themessagebackwardstoBreakthecoded message Almost everyoneisintriguedbysecrets Infact,overthe centuries

many famous people — and some infamousones,too— have usedsecret

methodsof writing Eventoday,governments,businessesandallsorts

oforganizations regularlyuse codestocommunicate.

Inour book,we'llintroduceyoutosomeofthetechniquesusedinthismysteriousglobalworldofcodes,ciphersandsecretwriting You'lllearnhow eachtechniqueworks .howtobreakthatkindofcode .

and howtousethattechniquetocreateyour ownsecretmessages

Andyou'llhaveplentytosolvewithallthe practicemessagesscattered

throughoutthesepages Thecartoonsmayhelpyousolve thesecrets

—

butiftheydon't,allofthe solutions are printedattheendofthe book

Havefun! Enjoy!

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1 [ereansometermscommonlyusedbyayptagrapheisBREAKING A CODE

Discovering(learning)theintricaciesof theformulathatsomeonehas usedto

create acodeunknowntoyou.Theprocess of unravellingsuchacode can be verycomplex,andmayrequirebreakingscores orhundredsoreven thousandsofcodedmessagesbefore the actualcodeitselfcanbe broken

BREAKING A MESSAGE

Theactoftranslating amessage from codeto cleartext

CLEARTEXTorINTHE CLEARorPLAINTEXT

Amessagewritten in plainlanguage,asopposedtoacodedorencipheredmessage

CODESand/orCIPHERS

These termsaresometimes usedinterchangeably Technically,however,

acoderequires theuseofacode book,or a pre-selectedbookor a periodical

knownonlytothesenderandthe receiver;bothmusthavethecode key being

usedforamessage Withoutthecodebook andcodekey,it isimpossibleto

breakacoded message

Ciphersaremoreinteresting.In a cipher,eachplaintextletterischanged

bysubstitutinganotherletterforit,orbytransposing(shifting)itinsomeway

Toavoid unnecessary confusioninterminology,thisbookuses thewords

"code,""encoding"and"decoding"todescribe selectedtechniquesforsecret

writing

CODE BOOK

A bookcontainingwordsand /or symbols usedincoded messages,together

withtheiractual (plaintext)meaning

Wordsorsymbols—sometimesbothusedincombination—todenotethe

typeofcode beingused,alongwithoneormorekey elementsof thecodeor

cipher Inthe"twistedpath"code, forexample(see pp 58-9), asample codekeyis

5x6V T I i J, R/L

—

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Slang(amongfellow professionals) for"cryptographer"or "cryptanalyst."CRYPTOGRAPHY

Theartandscience ofcreatingandbreakingcodesandciphers

In amonoalphabeticsystem,onelettersubstitutes foroneandonlyoneletter

In apolyalphabeticsystem,onelettermaystandinplace of differentletterswithin

thesamemessage

GARBLEorGARBLED MESSAGE

Anencoded messagethathasbeenmessed up duetoerrors initstransmission

or reception Thetextmayskiponeormoreletters,lettergroupsand/orwhole

sections ofthemessage

NULL(S)

A dummyornonsenseletterorgroupoflettersinserted inamessage—usually

atitsbeginningorend.Thepurposeofthe nullistofilloutashort (incomplete)

5-letteror4-lettergroupinanencoded message

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pimple JtZettei ^yzoupln^

It'seasytoreadthissentence . but .

ITSEA SYTOR EADTH ISSEN TENCE

willmake youstopandthinkbecauseitmakes nosenseandlooks soweird What doesitmean?

Here'show we made upthissecretmessage:

•First,we wroteout themessage"It'seasytoreadthissentence"

in capital letters— butwithoutany punctuation and withthewords

squeezed together:

ITSEASYTOREADTHISSENTENCE

(You havetoadmitthatitalready looks pretty mysterious!)

•Then wedivided themessageinto 5-lettergroups,like this .

ITSEASYTOR EADTHISSENTENCE

. and

—

prestochango— wecreated a simplesecretmessage!

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Did von knowthatwritingineither 4-lettergroupsor5-lettergroups

isthestandardwaythatprofessional cryptographersallover theworld encodetheirmessages? It'saquickwaytoslow down somebody's

readingspeed — andit'sespecially puzzlingforreaderswho have never

seenthistechniquebefore Inthisbook,we'll stick to 5-lettergroups

only

"It'seasytoreadthissentence"workedgreatbecause thosesixwords

divided evenlyinto 5-lettergroups But whatwillyou do withthis

message?

SECRET MEETING AT ONE

Changedintocode,itbecomes .

SECRE TMEET INGAT ONE What's wrong withit? It'stoo short.ThatE attheend needs two moreletterstocompleteits5-lettergroup

"Nulls"tothe rescue!Thesolutioniseasyifyou add two"nulls"

— any dummyornonsenseletters—tofilloutthatshort5-lettergroup

Forinstance,ifyoupickQXasyournulls,themessage wouldread:

SECRE TMEET INGAT ONEQX

Or you cancomplicate thecode even more byplacing the nullsatthe

beginning of thesecretmessage,just tomakeitsmeaning even harder

to solve:

QXSEC RETME ETING ATONE

As soonasyou breakthecoded messagesthatfollow,make up some

ofyour owntosendtoyourfellowcryptographers

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ANCEO FTHEN EWYOR KPUBL ICLIB RARYL OCATE

DATFI FTHAV ENUEA NDFOR TYSEC ONDST REETI

NNEWY ORKCI TYAKA THEBI GAPPL EOQBR

Decodedmessage:

Printoutthecompletemessageincapitalletters,withnospacesbetween

letters. Markaslash(/)betweenwordsastheyappeartoyou

Cleartextmessage:

Write outthecompletemessageinplainEnglish

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Secret Message No 2

THELO NEEAG LECHA RLESA UGUST USUN DBERG

HFLEW THESP IRITO FSTLO UISON HISHI STORI

CFLIG HTWHI CHINR ETROS PECTC ANBEL IKENE

DTOTH EPLAC INGOF THEFI RSTSP ANOFT HENOW

MUCHT RAVEL EDAIR BRIDG ERWMB

Decodedmessage:

letters. Markaslash( / )betweenwordsastheyappeartoyou

Cleartextmessage:

<±Cb

<Z^

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Code: Lettergrouping

Key: 5-lettergroups

Codedmessage:

THEPROFUSI ONOFP RODUC TSREL ATEDT OTHEI

NVENT IVEGE NIUSO FTHOM ASALV AEDIS ONTOU

CHTHE LIVES OFTHE MAJOR ITYOF THEPO PULAT

IONSP ANNIN GTHEG LOBEC ONTRI BUTIN GTOTH EIRCO MFORT ANDWE LLBEI NGBCR

Decodedmessage:

Printoutthecompletemessagein capitalletters,withnospacesbetween

Cleartextmessage:

Write outthecompletemessageinplain English

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Secret Message No 4Code: lettergrouping

Ko\ 5-lettergroups

Codedmessage;

EXHIB ITING RAREF ORESI GHTBL ESSED WITHO

RATOR ICALM AGNIF ICENC EANDP OSSES SINGA

SPIRA TIONS ANDDR EAMSB EYOND COMPA REDRM

ARTIN LUTHE RKING JRWAS ASING ULARG IANTW

ITHTH EPOWE ROFOU TSTAN DINGL EADER SHIPQ

[Suggestion:Ifoneofyourownsecretmessagesturnsupobvious or nearly recognizable

words—likeARTIN LUTHE RKINGinthemessage above—tryplacinganynullsatthe

beginning instead ofattheend.Thiswillhelpcomplicate the look of thecodedmessage.]

Decodedmessage:

Cleartextmessage:

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letters.Markaslash( / )betweenwordsasthey appeartoyou

Cleartextmessage:

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Secret Message No 6Code:

Key:

1ettergrouping

5-lettergroups

Codedmessage:

RECOG NIZED FORHE RDISTINGUI SHEDC AREER

ASANA SSIST ANTAT TORNE YGENE RALST ATESE

NATOR ANDAS UPERI ORCOU RTJUD GESAN DRADA

YOCON NORBO RNINE LPASO TXWAS THEFI RSTWO

MANAP POINT EDTOS ERVEA SANAS SOCIA TEJUS

TICEO FTHEU SSUPR EMECO URTMZ

[Inthe fourthline,noticehowtheabbreviationTXavoids spellingout"TEXAS"

as acomplete,andobvious,5-lettergroup.Inyourowndispatches,usecommon

abbreviationswhereverpossibletohelpconfuse the look ofyoursecretmessage.]

Decodedmessage:

Printoutthecompletemessagein capitalletters,withnospacesbetween

Cleartextmessage:

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NANDW ASNOT EDFOR HERAC COMPL ISHME NTSTO

WARDH ELPIN GTOEN DINST ITUTI ONALI ZEDDI

SCRIM INATI ONAGA INSTW OMENX

Decodedmessage:

Cleartextmessage:

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Secret Message No 8

Code: Lettergrouping

Key: 5-lettergroups

Codedmessage:

PTRPN URTUR INGTH ETHEO RYOFR ELATI VITYA

LBERT EINST EINBE CAMEA NOBEL LAURE ATEFO

RHISW ORKIN PHYSI CSALT HOUGH SOMEO FHISC

ONCEP TSANDTHEORIESDI DNOTG AINUN IVERS

ALACC EPTAN CEHIS SCIENTIFIC ANDSO CIALE

FFORT SANDF REETH INKIN GGAIN EDHIM WORLD

WIDER ECOGN ITION

Decodedmessage:

Cleartextmessage:

<(3«,<«-*)

t('»'-^^

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ECNET NESSI HTDAE RYDAE

RLAEV UOYTA HTWON KEWQX

willstopeverybodyin theirtracksbecauseitlookslikecomplete

nonsense What doesitmean? (Readitbackwards! The X and Q

arenulls.)

Here'show we made upthissecretmessage:

•First,we wroteout themessage .

"We knowthatyou'vealreadyreadthissentence"

in capital letters,but without anypunctuation:

WE KNOW THAT YOUVE ALREADY READ THIS SENTENCE

•Then we wroteitout backwards,withthewordssqueezedtogether:

ECNETNESSIHTDAERYDAERLAEVUOYTAHTWONKEW (Do you suppose aninterceptorwill try topronounceit?!)

•Then,aswedid before,wedividedthemessageinto 5-letter

groups,like this .

ECNET NESSI HTDAE RYDAE

RLAEV UOYTA HTWON KEWQX

. addingthenullsQXtofillout thelast5-lettergroup

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A"reversetrail"code may seemeasytobreak,butyoucanfool

eventhesmartest "spy"bytheway you choose your words.

Suppose you wantedtotellyour buddythatyoursecretmeeting

plannedfor 11a.m.hastotakeplaceat9a.m Instead of writing the

obvious message, youcouldsay:

WE HAVE TO DWARF[shorten]THE TIME ELEVEN

HUNDRED SHRINKS[goes back]TO ZERO NINE OH OH.

(Noticethatwe're using militarytalk todisguise11a.m.—"1100

hours" — and9a.m.—"0900 hours.")

Then,encodingthismessageasa"reversetrail,"you wouldwrite:

HOHOE NINOR EZOTS KNIRH SDERD NUHNE

VELEE MITEH TFRAW DOTEV AHEWR

(ThelastRisa null.)

Here'sa realopportunityforyourimaginationandinnovation

Butdon'toutsmartyourself! Becleverandcrafty,but becertainthat

your messagewillbeunderstood Clarityisessential inpreparing

amessage. Patience, common senseandcareful preparation are

essentialwhenitcomestimetoencodeit. Tosimplify thejob,you

may wanttohandprint your message onacopyofthe gridpaper

suppliednear the front of the book Use one boxforeachcapitalletter

As soonasyou breaktheencoded"reversetrail"messagesthat

follow, createsomeofyour owntosendtoyourfellowcryptographers

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SEOEG NIHTO NROFS KNAHT

•Goinginreverse—fromright toleft—printouteachcapitalletter,

oneafterthe other, untilyoureach thebeginningofthe secretmessage

•Don't leaveanyspacesbetweenletters.

•Markaslash( / )betweenwordsastheyappeartoyou.Cleartextmessage:

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Key:

Reversebrail

5-lettorgroups

Codedmessage:

VRQMT URANI KCUTS TEGUO YEROF

EBKCI UQEBK CAJEL BMINE BKCAJ

Decodedmessage:

•Goinginreverse—fromright toleft—printouteachcapitalletter,

oneafterthe other, untilyoureachthebeginningof the secretmessage

•Don'tleaveany spacesbetweenletters.

•Markaslash( / )betweenwordsastheyappeartoyou

Cleartextmessage:

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Secret Message No. 1

LLEWS DNETA HTLLE WSLLA

•Goingin reverse—fromright toleft—printout eachcapitalletter,

oneafterthe other, untilyoureachthebeginningofthe secretmessage

•Don't leaveanyspacesbetweenletters.

•Markaslash( / )between wordsastheyappeartoyou

Cleartextmessage:

— ^-7 \ ;v

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Remembertoreversethemessagewithnospacesbetween

letters-andmarka slashbetweenwordsastheyappeartoyou

Cleartextmessage:

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Code: Reversetrail

Key: 5-lettergroups

Codedmessage:

WMSEN IHSNU SEHTE LIHWY AHEKA MSTEL

Decodedmessage:

Remembertoreversethemessagewithnospacesbetweenletters

andmarkaslashbetweenwordsastheyappeartoyou

Cleartextmessage:

Y>"/''tilts ' ,^v^^

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VRHSU BEHTN IOWTH

TROWS IDNAH EHTNI DRIBA

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Code: Reversetrail

Key: 5-lettergroups

Codedmessage:

Decodedmessage:

Cleartextmessage:

OGNIH TDOOG AFOHC

UMOOT EVAHR EVENN ACUOY

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Secret Message No 16Code: Reverse trail

Key: 5-lettergroups

Codedmessage:

Decodedmessage:

OXRLL ATADA ERBON NAHTF

AOLAF LAHAR ETTEB

Cleartextmessage:

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Skijt Code

A"shiftcode"usesTWOalphabets,one ontop of the other

Theupper alphabetiscalled thePLAINTEXTalphabet.^>

Itshows your messageinplainEnglish. ^^

•PLAINTEXT A B C D E F G H I J K L M N O p Q R S T U V w X Y z

SHIFT A 6 c x> E F 6 H 1 K L M N o p QfcSTOVWXYZ

TheloweralphabetiscalledtheSHIFT alphabetbecauseit'sgoingtoslide(shift) alloverthe place!

Itwillshow yoursecretmessageincode(assoonasweshift it!).

Nowlet'sslidetheSHIFT alphabet oneplacetothe right

sothatletter"A"fallsrightunder PLAINTEXTletter"B."

Callthisa "SHIFT+1" code(todescribe that1-spaceslide):

This timelet'sslidetheSHIFT alphabetthree placestotheright

sothatletter"A" nowfallsrightunder PLAINTEXTletter"D."

Callthisa "SHIFT + 3" code(todescribe that3-spaceslide):

PLAINTEXT A B c D E F G H I I K L M N o p Q R s T u V w X Y z

SHIFT X Y Z A b c D E F <JH 1 vj K L M N p<k fc 5 T a V V^

^-J

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Forstarters,let'sdecodethesecretmessage belowusing the SHIFT+

code

3

IBQQE BDXJB PYBDF KWLON

STEP1: Write out both alphabets,movingthe SHIFT alphabet3places

totheright

A B c p E F G H I i K L M N o p Q K S T U V w X Y Z

STEP2: Letterbyletter,lookupthecoded messageinthe SHIFT alphabet:

I B .Q .andso on Thensubstituteeachof thoseletters

withitscorrespondingletterinthe PLAINTEXT alphabet:

(Thesubstitute forI isL .Thesubstitute forBisE .Thesubstitute forQ isT .

complete PLAINTEXT message(stillin 5-lettergroups):

STEP4: Finally,use commonsenseandlogic tofindone good word

aftertheotherinthePLAINTEXT message,untilyou havethe

complete messageinplain English.AplainEnglishmessageis

called a "cleartext"message,oramessagethat's"intheclear."

Thisonesays: V^ "ZORQ"are nulls

LET THE GAMES BEGIN ZORQ

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ALKQD FSBRM QEBPE FMZDO

Compositionfordecoding:

•Print theSHIFT+3alphabetbelowthisPLAINTEXTalphabet

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

Plaintextmessage:

•Letterbyletter,lookupthecoded messageintheSHIFT(lower) alphabet

•Thensubstituteeachofthoseletterswithitscorrespondingletterinthe

PLAINTEXT(upper) alphabet

•Printthecompleteplaintextmessagein 5-lettergroups

Cleartextmessage:

•Useslashes(/)todividethe plaintextmessageintorecognizablewords

•Write outthecompletemessageinplainEnglish

^U^

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•Print theSHIFT+8alphabetbelowthisPLAINTEXTalphabet

A B C D E F G H 1 1 K L M N P Q R S T U V vv X Y z

Plaintextmessage:

•Letterbyletter,lookupthecoded messageintheSHIFT (lower) alphabet

Cleartextmessage:

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No 19Code:

Key:

Shiftcode

SHIFT +2

Codedmessage:

GRQYQ NJYGL YQRFC LMQCM LWMSP DYACV

•PrinttheSHIFT+ 2 alphabetbelowthisPLAINTEXTalphabet

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

Plaintextmessage:

•Letterbyletter,lookupthecodedmessageintheSHIFT(lower) alphabet

Cleartextmessage:

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Secret Message No 20

Code: Shin code

•Asyou've already learnedtodo, substituteaPLAINTEXTletter

foreachletterinthe secretmessage

Cleartextmessage:

•Whatdoesthecoded messagesay?

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Code: Shiftcode

Asyou've already learnedtodo, substitute aPLAINTEXTletter

foreachletterinthesecretmessage

Cleartextmessage:

•Whatdoesthecodedmessagesay?

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Code: Shiftcode

Key: SHIFT+5

Codedmessage:

BZOOD IBVIV DNVWM ZZUZY VNCIJ OLSML

A B C D E F G H 1 J K L M N O P Q R S T U V w X Y ZPlaintextmessage:

Cleartextmessage:

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Code: Shiftcode

Key: SHIFT +5

Codedmessage:

KMJIO JJCOR JCPIY MZYOC

ZMVDY CDONV NKGVI IZYLU

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

Cleartextmessage:

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