COMPILER DESIGN

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ADVANCED TOPICS IN COMPILER DESIGN

CODE GENERATION FOR OBJECT ORIENTED LANGUAGES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The Caesar cipher, also known as a shift cipher, encrypts words by replacing each letter in the word with a letter that is a fixed number of positions forward in the alphabet. At the end of the alphabet, the cipher wraps around to the beginning of the alphabet. For instance, with a shift of 2, the word “zoo” is encrypted as “bqq.” For a student learning cryptography, which of the following activities best demonstrates the vulnerabilities of the Caesar cipher encryption technique?
A
Using a program that takes an input message and returns the Caesar cipher encrypted text
B
Using public and private key encryption to see how a more-secure encryption algorithm works
C
Analyzing the frequency of letters in the encrypted text to show how easy it is to break the Caesar cipher
D
Viewing program code that can both code and decode a message using the Caesar cipher
Explanation: 

Detailed explanation-1: -The Shift Cipher. Also known as the Caesar cipher, the shift cipher is one that anyone can readily understand and remember for decoding. It is a form of the substitution cipher. By shifting the alphabet a few positions in either direction, a simple sentence can become unreadable to casual inspection.

Detailed explanation-2: -The “Caesar Box, ‘’ or “Caesar Cipher, ‘’ is one of the earliest known ciphers. Developed around 100 BC, it was used by Julius Caesar to send secret messages to his generals in the field. In the event that one of his messages got intercepted, his opponent could not read them.

Detailed explanation-3: -The action of a Caesar cipher is to replace each plaintext letter with a different one a fixed number of places down the alphabet.

Detailed explanation-4: -With a shift of 3, every letter is replaced by the letter 3 letters to its right. Letters at the end of the alphabet wrap around to the beginning (e.g. ‘z’ shifted by 3 becomes ‘c’).

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