DOC

Transposition Ciphers

By Ronald Turner,2014-05-07 21:51
9 views 0
Transposition Ciphers

    Transposition Ciphers

    Caesar Shift Cipher

Assignment 1

CONTINUE TO ENCIPHER THIS MESSAGE YOU NEED TO REPLACE

    FRQWLQXH WR HQFLSKHU

EACH LETTER WITH THE LETTER BELOW IT ON THE CIPHER GRID

    HDF…

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

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

Using the same grid decipher the following remember to decipher

    from the lower grid to the upper.

Assignment 2

JHQLXV LV RQH SHU FHQW LQVSLUDWLRQ DQG QLQHWB QLQH

    SHU FHQW SHUVSLUDWLRQ TXRWH IURP WKRPDV HGLVRQ

    Shift Cipher

Similar to the example above, can you crack the cipher? How much

    does it shift?

Assignment 3

RCTQCA KIMAIZ AMVB BPM NQZAB SVWEV MVKQXPMZML

    UMAAIOMA NWZ UQTQBIZG XCZXWAMA PM LQL QB QV

    I AGABMUIBQK EIG JG APQNBQVO BPM ITXPIJMB

    NWZEIZL BPZMM XTIKMA BPQA XZWDML ZMTIBQDMTG

    MIAG BW LMKQXPMZ ZMXTIKQVO MIKP TMBBMZ EQBP

    WVM BPZMM XTIKMA JIKSEIZLA LQNNMZMVB KIMAIZ

    1

APQNBA KQXPMZA MFQAB JG UWDQVO I LQNNMZMVB

    VCUJMZ WN XTIKMA QN GWCZ MVMUG QVBMZKMXBML

    GWCZ UMAAIOM QB EIA VWB BWW LQNNQKCTB NWZ

    BPMU BW LMKQXPMZ

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

    Assignment 4 The Text Puzzle

Study this paragraph and all things in it. What is vitally wrong with

    it? Actually nothing in it is wrong but you must admit it is most

    unusual. Don’t just zip through it quickly but study it scrupulously.

    With luck you will spot what is particular about it and all words in it.

    Can you say what it is? Tax your brains and try again. Don’t miss a

    word or symbol. It isn’t all that difficult.

Hint: experienced cryptanalysts would spot the answer immediately.

    Look up Frequency Analysis in the Glossary.

Assignment 5

Encipher the following using a 6 shift

HE WHO MAKES NO MISTAKE NEVER LEARNS ANYTHING.

    ENGLISH PROVERB

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

2

    Shift Cipher Decipher the following, notice that there are no spaces shown

    between the words, which makes it harder. What techniques can

    you use to decipher? Do you know what is the most commonly used

    letter in the English Language?

Assignment 6

PDANASWOWJKHZIWJSEPDWXAWNZ

    SDKOWEZEPEOFQOPWOEBAWNAZ

    PSKKSHOWJZWDAJBKQNHWNGOWJZWSNAJ

    DWRAWHHXQEHPPDAENJAOPOEJIUXAWNZ

    XUAZSWNZHAWN

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

    Substitution Ciphers

    Keyword Cipher

Decipher the following using the cipher grid below. The cipher has a

    key word SPY notice how the rest of the alphabet is coded.

Assignment 7

DFUB JB PTR LKB CFOJ QMLR LK VEFYE RL QRSKA SKA F

    VFII JLUB REB BSORE NTLRB COLJ SOYEFJBABQ

    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

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

The following message for deciphering uses a different cipher and

    keyword can you crack the cipher.

3

    RMKT KTRRACTR AQT ITOS RTEQTS LMS GTEAURT SDTY Assignment 8

    AQT WQFSSTL FL EMNT GUS GTEAURT SDTY AQT DFNNTL SDFR FR ILMWL AR RSTCALMCQAODY FLVFRFGJT FLI ALN RDQFLIFLC KTRRACTR SM SDT RFZT MB A KFEQMNMS AQT WTJJ ILMWL KTSDMNR MB RSTCALMCQAODY MLT MB SDT KMRS ULURUAJ KTSDMNR URTN GY SDT CQTTIR WAR SM RDAVT SDT DTAN MB SDT KTRRTLCTQ SASSMM SDT KTRRACT ML DFR REAJO ALN SDTL NTROASED DFK MLET SDT DAFQ DAN CQMWL TVTL FB SDT TLTKY NFREMVTQTN ALN RTAQEDTN DFK LM KTRRACT WMUJN GT BMULN DMWTVTQ SDFR WAR EJTAQJY FL A OTQFMN MB DFRSMQY SDAS SMJTQASTN A JAEI MB UQCTLEY

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

4

    The Babington Plot

Babington code to be inserted here.

In the Sixteenth Century, there was an attempt to overthrow

    Elizabeth, Queen of England. Elizabeth had kept Mary, Queen of

    Scots, prisoner for many years. Some English Catholics were

    unhappy that England was led by a Protestant monarch and plotted

    to assassinate Elizabeth and rescue Mary, a Catholic, and have her

    instated as Queen of England. Babington led the plotters; they

    used both steganography and a substitution code. Unknown to the

    plotters the carrier of the message (who was unable to read the

    code) was a double agent and gave copies of the code to Elizabeth’s

    minister Walsingham, who used frequency analysis on the symbols

    to crack the code.

    Pig-Pen Code

Pig-pen code to be inserted here

Pig-pen code was developed in the Eighteenth Century and was

    used by the Freemasons; it had limited use since it was so awkward.

    Later in the Eighteenth Century the admiralty in Whitehall, London,

    needed to send messages quickly and efficiently to the Navy based

    in Portsmouth. The usual method had been to send a horse and

    rider, which were prone to kidnapping and took a lot of valuable

    time. A system of visual telegraphs, using semaphore, was set up

    relaying messages via thirteen strategically placed stations. One of

    which has recently been renovated near Guildford, in Effingham.

    When sensitive information was relayed it could be transmitted in

    code in case an enemy was watching.

    Decipher the following using Pig-Pen code

    Pig-pen phrase to be inserted here

    In the early Nineteenth century the advent of the telegraph inspired

    Morse code. Later the invention of radio meant messages could be

    sent quickly, but could be intercepted by anyone. The use of codes

    escalated during World War One. Armies needed to relay signals

    from Headquarters to the troops in the field. The enemy could easily

    listen to the radio signals so armies needed a code that was easy to

    encipher and decipher but difficult to crack. Coding became more 5

    sophisticated but it meant that valuable time was lost encrypting

    and decrypting messages for your own troops.

    Cryptanalysis

    Just as with the Babington Plot many codes are cracked using

    Frequency Analysis because certain letters are used more often

    than others. In English E then T are the two most frequently used

    letters; here is a grid with the relative frequencies of each letter i.e.

    the percentage of occurrences of each letter in English

7 1 3 4 13 3 2 3 8 1 1 4 3 8 7 3 1 8 6 9 3 1 1 1 2 1 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

Assignment 9

    Decipher the following, you may find Frequency Analysis useful

WDGGDRWDGGDRBMQQYSTRVRBMQQYADNFEKBJBMQQY

    TBQRRKJRTWKTBQRRRASQDNBMQATWKBRJQYCKUQCDV

    RSDXTBRJWBKRAWMQACKUQCDVRADNFTBROMABRJQYS

    RVRJRDHBTRATBRGMAIMQYRGDZMORTBEMIRSTBRVMDJ

    NBMQGDRNBMQGDREMIRSMHMDJWDGGDMIMJAIMQYMJJ

    MHGKQDMCKUQHRKQHRSWDGGDMIMJAVDNTKQDMRAMJ

    AHRKQHRMJARAMHMDJHRKQHRMJARGDZMORTBSTDGGD

    JQRDHJ

    6

    Assignment 10 Encrypt the following using the keyword ‘mission’; because the ‘i’

    and ‘s’ are repeated, but each letter can be used only once, you

    have to ignore the second appearance of each repeated letter.

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

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

EncryptingbyhandcanbetediousasyoumayagreeMechanisationwasincreasi

    nglyusedintheSecondWorldWarTheGermansdevelopedtheEnigmamachin

    ewithvariouscogwheelsEventhoughtheAllieshadcapturedseveralEnigmam

    achinestheywerestillunabletodeciphermessagesprecisedataaboutthearrang

    ementsofthecogwheelsandotherfactorswasessentialTheMathematiciansan

    dothercodebreakersatBletchleyParkeventuallycrackedthecodehoweverthe

    ykepttheirknowledgehiddensoastobeabletointerceptenemymessages

7

    Exercises

    Exercise 1

    Encipher the following quotation by Oscar Wilde using the cipher in

    the grid below, (notice the keyword is: codes).

I HAVE NOTHING TO DECLARE EXCEPT MY GENIUS

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

Again using the same cipher, decipher the following:

TFSQS GR MLJY MLS TFGLB GL TFS WMQJE WMQRS TFCL OSGLB

    TCJISE COMUT CLE TFCT GR LMT OSGLB TCJISE COMUT

    Remember that the grid is set up:

    PLAINTEXT

    CIPHERTEXT

    Which means that when enciphering you find each letter in the top

    line and write the letter in the lower line; however, when

    deciphering you read from the lower line and write from the top

    line.

Exercise 2

Using the keyword ‘SPY’ write out the cipher in the grid and then

    decipher the following text, ensure each letter is used only once.

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

    S P Y

JSYSUFRX Q S JXQRBOX YSR EB Q YSIIBA REB EFAABK MSV CLO

    EB Q REB JSQRBO YOFJFKSI VEL YSK ABCX REB ISV EB Q REB

    PSCCIBJBKR LC QYLRISKA XSOA REB CIXFKD QNTSA Q ABQMSFO

    CLO VEBK REBX OBSYE REB QYBKB LC REB YOFJB JSYSUFRX Q KLR

    REBOB PX R Q BIFLR

    Notice how ciphers avoid punctuation. Why do you think they do

    that?

8

Exercise 3

    Decipher the following using the keyword ‘DOG’.

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

TFB ANAN SDYS TFDT TFB FDTTBR TBKKS KHBS

    TFB FDTTBR SDYS TFDT TFB LDRGF FDRB TBKKS KHBS TFB LDRGF

    FDRB SDYS TFDT ONTF TFB ANAN

    DMA TFB FDTTBR TBKK KHBS

    WFNSB TBKKHME TFB TRUTF

Did you notice that the letters in the second half of the alphabet

    (after ‘O’) did not change?

    Why was that?

    How come when ‘SPY’ keyword was used ‘Z’ was the only letter that

    did not alter?

What are the requirements of a good keyword?

Exercise 4

Encipher the following, develop your own cipher, it can have a

    keyword, or just be a simple shift cipher.

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

There was a young woman of Ryde,

    Who ate a green apple and died,

    But the apple fermented inside the lamented

    And made cider inside ’er inside. By Edward Lear 9

Exercise 5

    Decipher the following, you will need to work out what cipher has been used; a keyword has been used. Hint: work on the shorter words first.

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

     BUBPXMLB EPTKAJBS RFB QIX VDQ EPBX

    VB FDS LMRFGLE RM SM DLS LMRFGLE RM QDX VB VBPB LBDPGLE RFB BLS MC D SGQKDJ SDX DLS RFBPB QBBKBS RM AB LMRFGLE ABXMLS RFBL SDSSX CBJJ GLRM RFB NMLS

    DLS BUBPXMLBQ CDYB EPBV KBPPX DLS APGEFR DLS RGKMRFX SDLYBS CMP QFBBP SBJGEFR

    EGUB KB RFB YDKBPD OTGYI MF OTGYI

    FBQ YPDVJGLE MTR MC RFB STYIVBBS YJGYI RFB EDPSBLBP QTSSBLJX QJDNNBS FGQ ILBB DLS SMTAJBS TN QFDIGLE QGJBLRJX

    RFB STYIQ DJJ OTDYIBS DQ GC RFBX VBPB SDCR GR QMTLSBS DQ GC RFB MJS SPDIB JDTEFBS MF RFBPB VDQLR D RFGLE RFDR SGSLR PBQNMLS VFBL SDSSX CBJJ GLRM RFB NMLS

10

Report this document

For any questions or suggestions please email
cust-service@docsford.com