COSC2651/CPT251 IT Security Assignment Report, OUA SP2 2018

This report delves into the practical aspects of IT security, focusing on decryption and encryption techniques. It begins by explaining various methods to decipher messages, including monoalphabetic substitution, Caesar shift ciphers, and polyalphabetic substitution. The report then analyzes the time required to decrypt messages using automated techniques on high-end consumer hardware, considering the CPU's processing power. Furthermore, it examines the techniques senders can employ to complicate the decryption process, such as employing advanced encryption standards like AES and Blowfish, and discusses their effectiveness. Finally, the report identifies factors that can either expedite or hinder the decryption process, such as the number of decryption keys and the use of video cards for parallel processing. The assignment is a response to a specific brief and adheres to submission guidelines, highlighting a student's ability to understand and articulate key concepts in IT security.

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Security in It and Information Technology
Student’s Name
Institutional Affiliation
Date

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Task 5
i. Explain what various techniques you could use to try to decipher the message (or simplify
the decryption process / bypass the decryption process altogether).
Decryption is the process of converting cipher text into plaintext. Conversely, the
highlighted below are some of the techniques which are used. The first technique is
monoalphabetic substitution. This involves each letter of the alphabet to be replaced as per the
key with another letter or symbol. The second technique is the Caesar shift cipher. This
technique requires a person to be told which Caesar cipher was used to decipher a message.
Probable word attack is another technique which involves having little knowledge about the
message is all about (Meingast, Roosta and Sastry 2016).
The fourth technique is polyalphabetic substitution based ciphers. In this technique,
multiple alphabetic strings are used to encode the plaintext. The fifth technique is transposition
based ciphers where the order of the plaintext is not preserved.
ii. For automated techniques estimate approximately how long the technique would take to
decipher the message on current high end consumer hardware (Intel Core i7 6950X
running at 3.0GHz).
The number of operations per second is usually influenced by the clock frequency. In this
case, the approximate time to decipher a message on a hardware running at 3GHz, Intel core i7
6950x is as illustrated below. To start with, the CPU usually fetches the instructions from the
memory and hence fetches data to operate if needed and executes it. Conversely, the CPU has a
frequency of 3GHz which means it can produce 3000, 000, 000 cycles per second. As for the

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manual technique, it will be much slower to decrypt a message up to around half of what the
automatic technique can take (Meingast, Roosta and Sastry 2016).
iii. What techniques could the sender use to make this decryption process harder and how
effective are they likely to be?
The sender could use advanced encryption standard uses keys of 192 and 256 bits for the
heavy duty encryption purposes (Alberts and Dorofee 2015). The second technique that could be
used by the sender is blowfish which is another algorithm designed to replace data encryption
standard. This technique usually works by splitting messages into blocks of 64 bits and hence
encrypts them individually. The other technique is triple DES which uses individual keys with 56
bits each. However, it usually has up to 168 buts total key length. This can make a dependable
hardware encryption for financial services along with other industries where data cannot be
decrypt easily.
iv. What factors will make the decryption process easier/faster? [20 marks]
One of the factors that usually makes decryption process easier is reduced number of
decryption keys has to be guessed. The second factor is that the chain is usually long and never
perfect. The proof only covers one part of the chain (Alberts and Dorofee 2015). The other factor
is the video cards which brings easy parallelism to cracking. As an illustration, the hardware
which goes through several triangles can also go through several passwords even faster.

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References
Meingast, M., Roosta, T. and Sastry, S., 2016, August. Security and privacy issues with health
care information technology. In Engineering in Medicine and Biology Society, 2006.
EMBS'06. 28th Annual International Conference of the IEEE (pp. 5453-5458). IEEE.
Alberts, C.J. and Dorofee, A., 2015. Managing information security risks: the OCTAVE
approach. Addison-Wesley Longman Publishing Co., Inc..