Problem $1$: CryptoAnalysis

The objective of cryptoanalysis is to break the code which someone is using as a secret

message to communicate. In this case, assume that you are part of the United States

Counter$-$Intelligence Department. You have just intercepted a message from a foreign

entity $($the enemy$)$ which looks like garbage. You know that the message is coded using

Ceaser$$s Cipher. You also know that the enemy is only using words from the following

vocabulary:

BOMB, MEETING, RIOT, PLANNED, PLANTED, NEW YORK CITY, BOSTON, SAN FRANCISCO,

WASHINGTON, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY,

SUNDAY, ON$,$ IN$.$

Can you write java code that will be able to figure out the coded message when the

boundary between words in the coded message is available.

The program should be able to take an input like:

ZDDJEFX QPMFFDO EF FDK STIY NEJS TF ZTFOMS

You should be able to determine that it stands for:

MEETING PLANNED IN NEW YORK CITY ON MONDAY

P$.$S$.$ In order to do the analysis, you may need to figure out the translation key, e$.$g$.$ this

encryption uses uses the following translation key. You may only be able to figure out the

translation key partially.

A $->$ M

C $->$ N

D $->$ O

E $->$ D

I $->$ E

K $->$ Y

L $->$ P

M $->$ Z

N $->$ F

O $->$ T

P $->$ Q

R $->$ I

T $->$ J

Y $->$ S

Be prepared to show your code in class, discuss the approach you used, and whether

arrays were the logical data structure to use the same.

For evaluation, the instructor will give you a code message which you will need to cryptoanalyze and produce the right plain text during your presentation.

Problem $2,$ Harder Cryptography:

Write a java program that does cryptoanalysis under the following conditions when the

enemy has gotten rid of all spaces in the coded message, so that you are not aware of

where the word boundaries lie.

The program should be able to take an input like:

ZDDJEFXQPMFFDOEFFDKSTIYNEJSFZTFOMS

You should be able to determine that it stands for:

MEETING PLANNED IN NEW YORK CITY ON MONDAY

Be prepared to show your code in class, discuss the approach you used, and whether

arrays were the logical data structure to use the same.

For evaluation, the instructor will give you a code message which you will need to cryptoanalyze and produce the right plain text during your presentation.

Problem $3$: Puzzle Solver

You must be familiar with puzzles of the following nature:

If$.$ then what is

ABC CJD

$+$DEF $+$ AAC

$---------$

EGI

Where each letter stands for one numeral from $0$ to $9,$ and there is a one$-$to$-$one mapping

between the numerals $0-9$ and the letters A$-$J$.$

In this case, you have the mapping that A $1,$ B$2,...$ I $9$ and J $0,$ leading to the

answer being DAG.