CSEC 630 Lab Assignment 1 Introduction To Cryptography Essay

1133 Words Mar 29th, 2015 5 Pages
Lab Assignment 1 - Introduction to Cryptography
Laurel Schneider
CSEC 630 - Prevention and Protection Strategies in Cybersecurity
University of Maryland University College
Jeffrey Daniels
February 21, 2015

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?
The Caesar cipher is a substitution cipher that substitutes one character for another and shifting the alphabet by a determined number of spaces. This type of cipher is vulnerable to statistical analysis. (Kendall, 2008). Therefore, a Histogram would be the most effective tool to use. The Histogram can be used to show “the relative frequency of each of the characters in
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Of the three ciphers discussed (Caesar, Vigenère, Playfair), what are their relative degree of security and why?
Using the entropy tool in CrypTool on the following ciphertext:
I came up with the following results:
Caesar 4.18
Playfair 4.46
Vigenère 4.59
According to our lab assignment, “generally speaking, a high calculated value is considered less likely to be deciphered by a cryptanalyst.” (CSEC 630 Lab Assignment 1 – Introduction to Cryptography, n.d.). Therefore, it appears that the Vigenère cipher is the most secure, followed by the Playfair and then the Ceasar.
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 [10 points]
b. an encrypted VoIP session [10 points]
c. viewing of a website using TCP/IP
According to our text Security Engineering by Ross Anderson, ECB is “adequate for many simple operations such as challenge-response and some key management tasks; it’s also used to encrypt PINs in cash machine stations”. (Anderson, 2008). However, “using ECB to encrypt message of more that an one block length…such as bank payment messages, would be foolish, as messages could be subject to

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