The document describes two encryption/decryption case studies. The first case study involves encrypting and decrypting 4-digit numbers by replacing each digit with its sum plus 7 modulus 10 and swapping the first and third digits and second and fourth digits. The second case study involves taking a text message and applying 14 rules to encrypt it by changing letters, removing vowels, and substituting letters and numbers for other letters and numbers. The encrypted text is then decrypted by applying the reverse rules.

1. Grand Assignment
Case Study-1
Encryption/Decryption
A company wants to transmit data over the telephone, but is concerned that its phones can be tapped. All
the data are transmitted as four digit integers. The company has asked you to write a pro- gram that
encrypts that data so that it can be transmitted more securely. Your program should read a four
digit integer and encrypt it as follows: Replace each digit by (the sum of that digit plus 7)
modulus 10. Then, swap the 1st
digit with the 3rd
, swap the 2nd
digit with 4th
and print the
encrypted integer.
Write a separate program that inputs an encrypted four digit integer and decrypts it to form the original
number?
Case study-2
Encryption A Text Message
The user will input a regular message or text. Your program will convert it into text message with
the following
rules:
Case 1
If the word contains `ee 'consecutively, change to `i '
Example:- meet into mit
Case 2
If the word starts with `qu 'or `c ', convert it to `kw 'or `k 'respectively
Example:- quit into kwit , cast into kast
Case 3
If the word end with `y ', change to `i '
Example:- jury into juri
Case 4
If the word contains vowel followed by a consonant, eliminate the vowel
Example:- text into txt
Case 5
If word contains with `ate ', change it to`8 '; and contains with `ite ', change `i ' to `y 'and eliminate `e '.
Example:- mates into m8, category into k8gori , site into syt , liter into lytr
Case 6
If the word contains same letter consecutively, eliminate one of it; if word contains `eas 'change to `I '
eliminate the next letter if vowel.
Example :- mass into mas , mirror into mirror , lease into lis , pleasant into plisnt , measure into misr
Case 7
If the word contains `ote ', change it to `ow 'and eliminate `e '; if word contains `at ', `ot 'or `ut 'change to
`@'
Example :- emote into emowt , hotshot into h@sh@
Case 8
If the word contains `ck', change to `k'; if word contains `sh' change to `sy'; if word contains `ou' change
to `aw'; if word contains `ks', `cts'change to `x.'
Example :- quick into kwik , checker into chekr , shoot into syut , loud into lawd , licks into lix , insects
into nsex
Case 9
If the word contains `oo ', change to `u '; if word contains `ex' or `ix ', change to `x '; if word contains `el
'or `il ', change to `l 'if not in front of the word.
Example:- book into buk , expert into xprt , gel into gl , illness into ilnes

2. Grand Assignment
Case 10
If the word contains `the ',`tha ', `da ', `de 'or `di ', change to `d'; if word contains `if 'or `ef 'change to `f 'if
not in front of the word and will not follow by `e ', otherwise change to `y ' and eliminate `e '
Example:- delimiter into dlimitr , there into dr , radar into radr , radix into radx , eects into efex ,
lift into lft , life into lyf
Case 11
If the word contains `ove ', change `o 'to `u 'and eliminate `e '; if word contains `ar ', `ur ', or `er 'change to
`r '; if word contains `to ', `too 'or `tu 'change to `2 '; if contains `wan ', `won 'change to `1 '; if `tre ', tree
'change to `3 '; if `for ', `fore ', `fur 'change to `4 '
Example :- love into luv , discover into dskuvr
Case 12
If the word contains `is 'or `es ', change to `s'; if contains `be', `bee'or `bi', change to `b'if the letter after it
is consonant, otherwise, change it to `by '; if contains `ti ', `te 'or `ty 'change to `t 'if the word is not
ends on it, otherwise, change to `ti '; if contains `yo 'or `yu ', change to `u '; if contains `ey 'or
`ay ', change to `i '; if contains `inâ?• or `en ', change to `n '.
Example :-beautiful into byutful , beauty into byuti , miss or mess into ms , message into msg ,
binary into bnari , bending into bndng , your into ur ,mbru into embryo
Case 13
If word contains numbers change to digit.
Example :- times three to tyms
Case 14
Eliminate all the vowels in the word if not in the above rule if not one syllable word.
Example :- eliminate into elmn8 , make into make
Example
Input: the quick brown fox jumps over the lazy dog
Output: d kwikbrwnfxjmpsovr d lzy dog
Input: life is so beautiful
Output: lyf s so butful
Input: I love you
Output: I luv u
Input: one moment please
Output: 1 mmntplis
Input: Later than the sunset, later than the rain.
Output: L8r dn d snst, l8r dn d rain
Instructor
Sunawar Khan
Deadline: - Dec 21, 2017
Code never lies, comments sometimes do.