CSC 290A Cryptology: E2 Rotating Grille

FYI, the prof did this in thirty minutes. Hand in just the answer (decrypts and the grille), along with all your intermediate work, scratch paper, scribblings, etc. This assignment is ripped off Toby's web site. All you need to know to solve it is a few pages from Gaines's Book. We'll get to the cryptograms in a minute, but first a little geopolitical background.

The People's Democratic Republic of Zurbia (Ratûrespublikum Demokrâtef Zerbû), located on the Dzeshret-plateau, has an area of 678.000 sq km and a population of 28.9 million. Capital: Hatan Bulag. Agriculture, forestry and mining are the principal industries. Timber, raw rubber, bauxite and industrial diamonds are exported.

The English were the first Europeans to explore the Dzeshret-plateau area, 16th century. Traditional backwardness in industry and administration ill prepared Zurbia for the demands of 19th century Western expansionism which exposed it to military and political humiliations, and mandated a drastic revision of political practice in order to secure an accommodation with the modern world.

The Republic of 1935 barely survived the stress of World War II Japanese occupation, and was subsequently all but shattered by the rise of nationalism and the emergence of the Zurbian Communist movement. Moscow, which practiced a policy of cooperation between Communists and other parties in movements for national liberation, sought to establish an entente between the Zurbian Communist Party and the Partî Ratomo-movement ('People's Party') of General A. Klinkanai. The ensuing cooperation was based on little more than the hope each had of using the other.

An increasingly uneasy association between the Partî Ratomo and the Zurbian Communist Party developed and continued until July 31, 1965, when General A. Klinkanai took over power through a coup-de-etat. He has ruled the country with iron-hand ever since.

[Note: Text in italics denote genuine Zurbian - the native language of Zurbia, but all plaintext contained in any Zurbian cryptograms given here will be in English.]

The Zurbian Ground Forces held their annual manoeuvres last week, and here are a few intercepted messages. They are believed to have emanated from low-level units, probably companies and a controlling batallion. There are reason to believe they have used a turning grille to encrypt their traffic. Traffic at this level usually consists of battle reports, requests for reinforcements, supplies and the like. 

Your vital mission -- break the messages and reconstruct the grille used. Good luck! The Fatherland is counting on you.

The messages:



"JUNGLE", "JUNGLE" this is "PUMA" do not answer, message follows:

Groups 4, text: SANO RITT RTEI OUXP. End of message. Out.



"PUMA" this is "TIGER". Message follows:

Groups 4, text: ASER ELXL TQHU IIXE. Over.

"TIGER" this is "PUMA". Message understood. Out.



"PUMA" this is "LION". Message follows:

Groups 4, text: EYIY LNOE VAIC TMWT. Over.

"LION" this is "PUMA". Message understood. Out.



"PUMA" this is "JAGUAR": Msg follows:

Gr 4, txt: NIOO ROTT RNEG THXP. Over.

"JAGUAR" this is "PUMA". OK. Out.



"PUMA" this is "LEOPARD": Msg follows:

Gr 4, txt: ASLE XLXL HWEE LIXR. Over.

"LEOPARD" this is "PUMA". Msg understood. Out.



Flash, flash "PUMA" this is "JAGUAR": Urgent msg:

Gr 4, txt: EYTK INNE TIAS AMGC. Over.

"JAGUAR" this is "PUMA". Msg understood. Out.



"JAGUAR" this is "PUMA": Msg follows:


"PUMA" this is "JAGUAR". OK. Out.



"PUMA" this is "JAGUAR": Msg follows:

Gr 4, txt: WERI NEGA ERAE TRXT. Over.

"JAGUAR" this is "PUMA". Msg understood. Out. 


As usual, submit your PDF writeup to webCT.


This page is maintained by CB.

Last update: 21.8.03.