Cyber Security and Traffic

Running head: CYBER SECURITY AND TRAFFIC
Cyber Security and Traffic
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Question 1: Vignere cipher programming algorithm
The program written here summarizes the Vignere cypher algorithm. The Vignere cypher is a
polyalphabetic cypher which is used to encrypt messages and then decrypt it using a single
key. It is a type of symmetric algorithm as it uses the same key for both encryption and
decryption (Radwan, AbdElHaleem and Abd-El-Hafiz 2016). The program written is very
efficient as it uses the algebraic equivalent of the vignere cypher algorithm to both encrypt
and decrypt the data. The program written does not use any complex functions and is
relatively easy to understand. The program uses basic numerical calculations to implement
the algorithm. The Vignere cypher is quite a robust algorithm and has fewer weakness. The
algorithm due to its polyalphabetic substitution is quite difficult to break in and cannot be
hacked without knowing the secret key (Ardy et al. 2017). This cypher is especially suitable
for small text messages as theoretically it becomes impossible to break this encryption if the
message length and the key length is same. For example, in Vignere cypher due to the
polyalphabetic substitution and the interwoven Caesar cyphers, if a message of length 10
characters is encrypted using a randomly generated key of 10 characters it becomes
impossible to break this message without the key (Oktaviana and Siahaan 2016).
The functioning of the Vignere cypher is quite simple. The cypher uses a table to
encrypt and decrypt its data. The table is given below:

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Figure 1: Vignere cipher polyalphabetic cipher
For example, let us assume the message as HELLO. Let the key be ASDAS. The algorithm
checks the first letter of the message with the first letter of the key and selects the letter than
coincides both rows in the table. This letter is H. So following this procedure if we encrypt
the data the message becomes: HWOLG. This is algebraically given in the program as Ei =
(Pi + Ki) mod 26, where P is plain text and K is key. The same process is repeated to decrypt
the message using the Pi = (Ei – Ki + 26) mod 26 expression, where E is the encrypted
message and K is the key. The program utilises both these expressions to implement the
algorithm.
This algorithm is best suitable to be used between two persons during communication
because between two people if the key is kept private and secure, it will be practically
impossible for an outsider to decode their messages without the secret key (Chou, Bloch and

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Abbe 2015). This helps in proper encrypting of the communication line and providing better
security.
Question 2: Policies for securing data, deletion and recovery
There exists various set of policies and procedures for securing, deleting and
recovering data. These policies vary as there are different types of operating systems
(Tanenbaum and Bos 2015). The security policies of operating systems outline processes of
ensuring the OS meets the required integrity and confidentiality levels as well as availability.
The OS security system provide protection from threats like virus, worm, malwares,
ransomware attacks as well as backdoor intrusions and others (Nourian and Madnick 2018).
Such protection is made possible through the security policies employed by operating
systems to cover preventive techniques and measures so as to safeguard a particular operating
system, the associated data that can be edited, stolen or destroyed as also the network that the
OS is connected to.
These security policies cover broad areas in securing OSes by protecting from attacks
and threats in several ways (Dautenhahn et al. 2015). These can be:
 To ensure that systems are kept updated with the latest patches and hostfixes.
 Installation of antivirus software and updating the definitions.
 Installation of firewall applications and making sure that these are configured
appropriately for monitoring incoming as well as outgoing traffic.
 Implementation of procedures for managing and securing accounts and
privileges of users.
For ascertaining that the right policies and procedures get defined one first requires to assess
the hardware, systems, assets and data that play a critical role for the business (Massa, Tucci