CP3404 Assignment 1
SP53, Singapore (2021)
Due Friday on Week 8 (no later than 9:00pm)
Aim: This assignment is designed to help you improve your critical thinking and
problem solving skills, as well as your information literacy skills (i.e. the ability to
select and organise information and to communicate it effectively and ethically).
Requirements, Method of Submission, and Marking Criteria:
Answer all of the following questions in a single document. Each question
should begin on a new page.
Include your name on the first page.
Include list of references for each question with proper in-text citations.
For each of the first two (2) questions, write a report of approximately 750
words in the structure of a scientific paper (e.g., articles and/or conference
papers).
In your answer to question 3 (i.e., cryptanalysis), show all your work. Note
that using the Internet for deciphering the cryptogram and/or learning the
key from any other sources is an instance of plagiarism. You have to show
(step-by-step) how did you achieve the plaintext and key.
For marking criteria, see the included rubrics.
Upload your solution to the Assignment Box, located in the subject’s site.
1. Answer a) OR b)
a)
Using the web, find out who Kevin Mitnick was.
What did he do?
Who caught him?
Write a short summary of his activities and why he is famous.
b)
What went wrong at Sony Entertainment? Review the Fortune Magazine article Hack of
the Century and other resources and summarize what went wrong and why.
[5 marks]
2. One-Time Pad (OTP) – An unbreakable cryptographic system
Use the Internet to search OTPs; who was behind the initial idea, when they were first used,
in what application they were found, how they are used today, etc. Then visit an online OTP
creation site (such as www.braingle.com/brainteasers/codes/onetimepad.php) and
practice creating your own ciphertext with OTP. Exchange your OTPs with other students
to see how you might try to break them. Would it be practical to use OTPs? Why or why
not? Can you find any references about its use in practical situation? Write a short
summary on your findings.
[5 marks]
3. Cryptanalysis of Substitution Ciphers
In this question you learn a classical monoalphabetic (substitution) cryptographic system,
and are required to cryptanalysis a given cryptogram.
In substitution ciphers, a permutation of the alphabet is chosen as the cryptogram of
original alphabet. That is, every letter of the plaintext substitutes by corresponding letter in
the permuted alphabet. For example,
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
c o d k s z r g e l u y a f m v p h i n w t b j q x
Figure 1: A possible permutation of English alphabet
is one of such permutation, in which letters a,b,c,···,y,z from the plaintext are substituted by
corresponding letters c,o,d,···,q,x respectively. Since remembering permutation is not easy,
one may employ a keyword and use a table to generate the permuted alphabet. Let
CRYPTOGRAPHY be the keyword. The permuted alphabet can be obtained as follows.
Choose a 6 × 5 table/matrix, i.e., a table with 6 rows and 5 columns.
Write down the secret keyword in cells (1,1),(1,2),···, one letter in each cell, but skip
repeated letters. Figure 2 shows how ‘CRYPTOGRAPHY’ (as a keyword) written down in
the table.
Write alphabet letters (in order) from the first available cell after keyword, but skip all
letters that are already written in the table. You will come out with Table 3.
The permuted alphabet, which will be used to generate the cryptogram, can be obtained by
simply reading the content of Table 3 in columns order (Which gives you the cryptogram
alphabeth of Figure 1).
Figure 2: CRYPTOGRAPHY is the Keyword
Figure 3: Table for permuting alphabet
Your Task:
Cryptanalysis of an information system is the study of mathematical techniques for
attempting to defeat information security services.
A cryptographic system is said to be breakable if a third party (i.e., cryptanalyst), without
prior knowledge of the key, can systematically recover plaintext from corresponding
ciphertext within an appropriate time frame.
In this question, you are required to determine the plaintext and the keyword associated to
the given cryptogram. Note that brute force attack (i.e., searching all possible keys) in order
to find the keyword is not efficient. However, letter frequency attack and redundancy in
natural languages are efficient tools for breaking substitution ciphers.
In the following you can find 20 cryptograms, where the breaks are genuine breaks
between English words, and any non-alphabet characters have not been changed. You are
required to decipher the cryptogram that matches with the last two digits of your
StudentID. For example: if your student ID ends with 73 then cryptogram number 8 is
yours.
[10 marks]
1 Cryptogram for whom their Student-ID is XXXXXX[02468]0
vugdugqm jm a iqfwxrug-lurhqgv axreulrjiarjql wgqrqiqc rear hqgvm ql
reu damjm qz rjivurm rq accqh lqoum iqffxljiarjlt qbug a lql-muixgu
lurhqgv rq wgqbu reujg joulrjrs rq qlu alqreug jl a muixgu fallug.
reu wgqrqiqc ham lafuo azrug reu ieagairug vugdugqm zgqf tguuv
fsreqcqts, reu zugqijqxm reguu-euaouo txago oqt qz eaoum. jrm
oumjtlugm ajfuo jr wgjfagjcs ar a icjulr–mugbug fqouc, alo jr
wgqbjoum fxrxac axreulrjiarjql am dqre reu xmug alo reu mugbug
bugjzs uaie qreug'm joulrjrs. vugdugqm wgqrqiqc fummatum agu
wgqruiruo atajlmr uabumogqwwjlt alo guwcas arraivm.
2 Cryptogram for whom their Student-ID is XXXXXX[13579]0
muheus mblejko mhbudum wercjpu zre sbu muheuht rz mukmjsjcu
jkzredlsjrk at wlesjsjrkjko js jksr mucuelg wlesm jk mxhb l flt sbls
l mwuhjzjup kxdaue rz sbu wlesm dxms au hrdajkup jk repue sr euhrcue
sbu rejojklg jkzredlsjrk. mr, grmjko l wjuhu prum krs hrdwerdjmu sbu
muheus, sbls jm, sbu rwwrkuks hlkkrs gulek sbu muheus lm grko lm bu
prum krs blcu lhhumm sr l weupusuedjkup kxdaue rz wjuhum.
3 Cryptogram for whom their Student-ID is XXXXXX[02468]1
bwlmc-zvymki vwmapdmcyvmckd cf vd plpymikdcy vwmapdmcyvmckd bpmakh
cd tacya v wfpi cf uivdmph vyypff mk v tprfcmp ki vsslcyvmckd kdlo
vzmpi fwyypffzwllo sipfpdmcdu mtk ki bkip scpypf kz pechpdyp (ki
zvymkif) mk vd vwmapdmcyvmckd bpyavdcfb: qdktlphup (fkbpmacdu kdlo
map wfpi qdktf), skffpffckd (fkbpmacdu kdlo map wfpi avf), vdh
cdapipdyp (fkbpmacdu kdlo map wfpi cf). bwlmc-zvymki
vwmapdmcyvmckd sikmpymf wfpi hvmv—tacya bvo cdylwhp spifkdvl
chpdmczcyvmckd ki zcdvdycvl vffpmf—zikb rpcdu vyypffph ro vd
wdvwmakicfph macih svimo mavm bvo avep rppd vrlp mk hcfykepi, zki
pgvbslp, v fcdulp svfftkih.
4 Cryptogram for whom their Student-ID is XXXXXX[13579]1
bqcu wcuhjlust, hctwrqecdwat jl rau xlu qz rcdklzqcbdrjqkl qz odrd
jkrukouo rq bdvu rau odrd xlusull rq qwwqkukrl, nxr budkjkezxs rq
suejrjbdru cuhujgucl. rau qkst luhcur wdcr qz dsbqlr dss bqouck
hctwrqecdwajh ltlrubl, aqfuguc, jl rau vut --rau wdcdburuc radr
lusuhrl rau wdcrjhxsdc rcdklzqcbdrjqk rq nu ubwsqtuo.
5 Cryptogram for whom their Student-ID is XXXXXX[02468]2
jmfwlj jxbr wuuqweqj cf bmnqjcb emlqg cf wfcnwoqj bweommfg. jmfwlj'g
zcego osqwoecbwl wuuqwewfbq ywg cf osq ycgq lcoolq sqf (1934), ixo
co ywg scg gqbmfj wuuqwewfbq cf meuswf'g iqfqzco oswo gwnq pqwe oswo
cfoemjxbqj scn wg w oqnuqewnqfowl bmncb zmcl om ncbrqp nmxgq.
osemxasmxo osq fqho oym jqbwjqg, jmfwlj wuuqweqj cf mdqe 150
osqwoecbwl zclng, gqdqewl mz yscbs yqeq eqbmafcyqj wo osq wbwjqnp
wywejg. cf osq 1930g, sq opucbwllp wuuqweqj wg uweo mz w bmncb oecm
ycos ncbrqp wfj ammzp wfj ywg acdqf scg myf zcln gqecqg goweocfa
ycos jmf jmfwlj (1937). osqgq zclng cfoemjxbqj jmfwlj'g lmdq
cfoqeqgo wfj uqenwfqfo acelzecqfj jwcgp jxbr wfj mzoqf cfblxjqj scg
oseqq fqusqyg sxqp, jqyqp, wfj lmxcq. wzoqe osq zcln bscug wsmp
(1956), jmfwlj wuuqweqj uecnweclp cf qjxbwocmfwl zclng iqzmeq
qdqfoxwllp eqoxefcfa om osqwoecbwl wfcnwocmf cf ncbrqp'g bsecgonwg
bweml (1983). scg lwgo wuuqwewfbq cf w osqwoecbwl zcln ywg cf
zwfowgcw 2000 (1999). smyqdqe, gcfbq osqf jmfwlj swg wuuqweqj cf
jceqbo-om-dcjqm zqwoxeqg gxbs wg ncbrqp, jmfwlj, ammzp: osq oseqq
nxgrqoqqeg (2004), oqlqdcgcmf gqecqg gxbs wg ncbrqp nmxgq blxismxgq
(2006–2016), wfj dcjqm awnqg gxbs wg txwbrgsmo (1991).
6 Cryptogram for whom their Student-ID is XXXXXX[13579]2
bxak bxjjs ik cj cjiecqum hcfqppj hdcfchquf, hfucqum ij qdu rcqu
1930k bs rupj khdrukijauf wfpmxhqipjk (rcquf gcfjuf bfpk. hcfqppjk)
cjm tpihum pfiaijcrrs bs eur brcjh. bxak ik bukq vjpgj zpf dik
kqcffija fpruk ij qdu rppjus qxjuk cjm euffiu eurpmiuk kufiuk pz
cjiecqum kdpfq zirek, wfpmxhum bs gcfjuf bfpk. bxak ik cj
cjqdfpwpepfwdih afcs cjm gdiqu fcbbiq pf dcfu gdp ik zcepxk zpf dik
zriwwcjq, ijkpxhicjq wufkpjcriqs. du ik crkp hdcfchqufiyum bs c
bfppvrsj chhujq, dik wpfqfcscr ck c qfihvkquf, cjm dik hcqhd wdfcku
"ud...gdcq'k xw, mph?". mxu qp bxak' wpwxrcfiqs mxfija qdu aprmuj
cau pz ceufihcj cjiecqipj, du buhceu jpq pjrs cj ceufihcj hxrqxfcr
ihpj cjm qdu pzzihicr eckhpq pz gcfjuf bfpk. ujqufqcijeujq, bxq crkp
pju pz qdu epkq fuhpajiycbru hdcfchqufk ij qdu gpfrm. du hcj qdxk bu
kuuj ij qdu prmuf gcfjuf bfpk. hpewcjs rpapk.
7 Cryptogram for whom their Student-ID is XXXXXX[02468]3
sjksjk jm snu sjsxlbd wdrsberkjms rz snu bpiuksxdum rz sjksjk, snu
hrcjhm mudjum at aulejbk hbdsrrkjms nudeé. nu jm b duwrdsud bkp
bpiuksxdud fnr sdbiulm bdrxkp snu frdlp fjsn njm pre mkrft. snu
hnbdbhsud fbm hdubsup jk 1929 bkp jksdrpxhup jk lu wusjs ijkesjucu,
b fuuvlt trxsn mxwwlucuks sr snu aulejbk kufmwbwud lu ijkesjucu
mjuhlu. nu bwwubdm bm b trxke cbk, bdrxkp 20 sr 30 tubdm rlp (axs
nudeu kuiud ejiu njc bk uobhs beu) fjsn b drxkp zbhu bkp gxjzz
nbjdmstlu. sjksjk nbm b mnbdw jksulluhs, hbk puzukp njcmulz, bkp jm
nrkums, puhuks, hrcwbmmjrkbsu, bkp vjkp. sndrxen njm jkiumsjebsjiu
duwrdsjke, gxjhv-snjkvjke, bkp bll-bdrxkp errp kbsxdu, sjksjk jm
blfbtm balu sr mrliu snu ctmsudt bkp hrcwlusu snu bpiuksxdu. xkljvu
crdu hrlrxdzxl hnbdbhsudm snbs nu ukhrxksudm, sjksjk'm wudmrkbljst
jm kuxsdbl, fnjhn bllrfm snu dubpud krs cudult sr zrllrf snu
bpiuksxdum axs bmmxcu sjksjk'm wrmjsjrk fjsnjk snu msrdt. hrcajkup
fjsn nudeé'm mjekbsxdu "hlubd ljku" mstlu, snjm nulwm snu dubpud
"mbzult uksud b mukmxbllt msjcxlbsjke frdlp".
8 Cryptogram for whom their Student-ID is XXXXXX[13579]3
ghzncbpognh wcnosfognh fnascj hno nhiq jsfcsfq, p ocplgognhpi
wcnosfognh prpghjo spasjlcnwwghr, txo pijn pxoeshogfpognh,
ghosrcgoq, ascgzgptgigoq phl noesc bncs jwsfgzgf jsfxcgoq
fnxhoscbspjxcsj. fcqwonrcpweq gj oes jfgshfs oepo lspij dgoe oes
lsjgrh nz pirncgoebj, wcnonfnij phl jqjosbj znc jniaghr odn ughlj nz
jsfxcgoq wcntisbj: wcgapfq phl pxoeshogfpognh.
9 Cryptogram for whom their Student-ID is XXXXXX[02468]4
bgiigq bnxjq gj s fsconni frscsfoqc fcqsoql ap orq dseo lgjiqp fnbvsip.
sj orq eniwogbq jdqqorqsco nz bgfuqp bnxjq, jrq gj si siorcnvnbncvrgf
bnxjq dgor drgoq wenhqj, s and, vneus-lnooql lcqjj, sil end-rqqeql jrnqj
nffsjgniseep dgor cgaanij ni orqb. orq bgfuqp bnxjq fnbgf jocgv joncp
"orq weqsb" (vxaegjrql msixscp 19 – bsp 2, 1942) ap bqccgee lq bscgj sil
zenpl wnoozcqljni zgcjo wshq rqc zxee isbq sj bgiqchs bnxjq, seornxwr
orgj gj jqelnb xjql.bgiigq gj fesjjp, fseb, jsjjp, dqee-bsiiqcql,
frqqczxe, sil zqbgigiq. jrq gj zgeeql dgor enhq sil szzqfogni, vnegoq on
see rqc zcgqilj, sil uindj rqc bsiiqcj. orq fnbgf jocgv joncp "bc.
jegfuqc sil orq qww cnaaqcj" (vxaegjrql jqvoqbaqc 22 – lqfqbaqc 26, 1930)
giocnlxfql rqc zsorqc bscfxj bnxjq sil rqc xiisbql bnorqc, anor zscbqcj.
orq jsbq joncp zqsoxcql vrnonwcsvrj nz bgiigq'j xifeq bgeoni bnxjq dgor
rgj zsbgep sil rqc wcsilvscqioj bschqe bnxjq sil bsogels bnxjq. rqc aqjo-
uindi cqesoghqj, rndqhqc, cqbsgi rqc xifeq bncogbqc bnxjq (bncogbqc dsj
sebnjo orq isbq nz bgfuqp) sil rqc odgi igqfqj, bgeegq sil bqenlp bnxjq,
ornxwr bnjo nzoqi s jgiweq igqfq, bqenlp, svvqscj. gi bsip svvqscsifqj,
bgiigq gj vcqjqioql sj orq wgcezcgqil nz bgfuqp bnxjq, sil gj aqjo
zcgqilj dgor lsgjp lxfu, sil s zcgqil on fescsaqeeq fnd.
10 Cryptogram for whom their Student-ID is XXXXXX[13579]4
uosulmkgu fumucfjb bcm euul jrlpxjsup kl rfpuf sr kdwfrgu sbu mujxfkst
clp uzzkjkuljt rz uaujsfrlkj cxjskrlm. briuguf, lrs dxjb cssulskrl bcm
euul wckp sr sbu pumkhl kmmxum.
kl sbkm wcwuf, iu pkmjxmm mujxfkst, sfxms, clp pumkhl kmmxum jrlsfcmsklh
sbu pkzzufuljum eusiuul gcfkrxm cxjskrl stwum.
iu ikaa mbri sbcs wrrf pumkhl zrf cl uaujsfrlkj cxjskrl efucjbum sbu
mujxfkst rz sbu mtmsud clp puhfcpum ksm wfcjskjcakst --lr dcssuf bri
mujxfu uzzkjkuls cfu sbu exkapklh earjvm rz cl uaujsfrlkj cxjskrl.
zxfsbufdrfu, iu pkmjxmm c mus rz funxkfudulsm zrf wfcjskjca clp mujxfu
uaujsfrlkj cxjskrlm (lrsu sbcs caa uokmsklh klsuflus cxjskrl mksum bcgu
lr mujxfkst --luksbuf zrf sbu ekpm lrf zrf sbu ekppufm-- clp sfxms km
zxaat wacjup kl sbu cxjskrluuf, ibkjb km lrs cjjuwsceau zfrd fumucfjb
wrklsm rz gkui).
11 Cryptogram for whom their Student-ID is XXXXXX[02468]5
ij ticvs ij rat zgzra fthrxcs e.f. rat jwicrihj tjrievgjatm rat zgcjr
jsjrtb qz bgvgrics fcswrqnciwas. fcswrqnciwas gh grj ticvs sticj
ctjtbevtm ltcs bxfa jtfctr dcgrghn. rat dtvv uhqdh fitjic fgwatc, dagfa
dij xjtm rq thfcswr bgvgrics qcmtcj, gj ih tkibwvt qz ragj nthtcirgqh. gh
ragj jsjrtb faicifrtcj dtct rcihjzqcbtm xjghn i ltcs jgbwvt jxejrgrxrgqh.