Essay on Week 3 Lab Assignment

977 Words Mar 10th, 2015 4 Pages
CSEC 630 – Lab Assignment

Q1. Which tool or technique from the above list would be most effective for a cryptanalyst to use to decipher a text encrypted with the Caesar cipher, and why?

Floating frequency is the most effective tool used to decipher a text encrypted with the Caesar cipher. Floating frequency replace one letter of the plaintext with another to produce the cypher text, and any particular letter in the plaintext will always, in the simplest and most easily breakable of these cyphers, turn into the same letter in the cypher. For instance, all E's will turn into X's. Floating frequency is based on the fact that certain letters, and combinations of letters, appear with characteristic frequency in essentially all texts in a
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The Caesar cipher is less secured because it is very easy to the key. For the Caesar cipher there are 26 alphabet characters meaning there are 25 possible keys and the 26 key would be in plaintext. All someone have to do to crack the code is to try all alphabet shift until the coded message is revealed (Caesar Shift Cipher, 2011).
The Vigenere cipher can be crack as well because the security of this cipher is directly related to the length and security of the keys. The code can be crack simply by guessing the key length (Vigenère Cipher, 2011).
As far as Playfair goes it is more secured because then instead of the 26 alphabet characters the Caesar cipher uses, Playfair instead uses 600 possible characters to determine the code (Playfair Cipher, 2013).

Q5. For each of the following say whether ECB or CBC would be most appropriate and give a brief explanation as to why.
a. an online bank statement
b. an encrypted VoIP session
c. viewing of a website using TCP/IP

A. CBC would be used for an online bank statement because bank statements included a lot of personal information such as account numbers, bank transactions and account balances.

B. ECB would be used for an encrypted VoIP session because VoIP protocols are connectionless. C. When viewing of a website using TCP/IP I would recommend CBC because TCP/IP delivers packets in order and TCP/IP is not connectionless which means

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