Cipher methods-cryptography, Computer Network Security

Assignment Help:

Cipher Methods

There are 2 methods of encrypting plaintext:

• Bit stream method – every bit in the plaintext bit is transformed into a cipher bit one bit at a time.
• Block cipher method – the message is divided into blocks (for example sets of 8-, 16- or
32-bit blocks) and then each block of plaintext is transformed into an encrypted block of cipher bits by using an algorithm and a key.

Bit stream method which is uses algorithm functions like XOR, while block cipher method can use substitution, transposition, XOR, etc.

Substitution cipher

Substitution cipher substitutes one value for the other value. The following are the different types of substitution:
• Monoalphabetic substitution – It uses one alphabet to substitute. Simple method but powerful if combines with other operations.
• Polyalphabetic substitution – It is more advanced method which uses two or more alphabets.
• Vigenère cipher – It is an advanced type of cipher which uses simple polyalphabetic code that is made up of 26 distinct cipher alphabets.

Transposition cipher


Transposition cipher rearranges values within the block to create ciphertext.

Exclusive OR (XOR)

It is a function of Boolean algebra where the two bits are compared to each other
•     If the two bits are identical, result is 0
•     If the two bits not identical, result is 1

Vernam cipher

This is developed at AT&T that uses set of characters once per encryption process.

Book (or Running Key) cipher

This method uses text in book as key to decrypt a message where ciphertext contains codes which represents page, line and word numbers

Hash Functions

Hash functions are mathematical algorithms that generate message summary or digest to confirm message identity and confirm no content has changed. Hash algorithms are publicly known functions that create hash value. Use of keys is not needed, but message authentication code (MAC) may be attached to a message. This method is mostly used in password verification systems to confirm identity of user.


Related Discussions:- Cipher methods-cryptography

Describe the functioning of cloud computing, Question 1:  Describe the ...

Question 1:  Describe the functioning of cloud computing. Question 2: Discuss on "Platform as a Service". Question 3: Discuss the steps involved in effective co

Describe phishing attacks, QUESTION (a) (i) Describe Phishing attacks. ...

QUESTION (a) (i) Describe Phishing attacks. (ii) Distinguish between Phishing and Spear Phishing attacks. (b) Describe two instances where an attacker sniffing on a netwo

Ids-information security, IDS Intrusion is a attack on information assets...

IDS Intrusion is a attack on information assets in which instigator attempts to gain entry into or disrupt normal system with harmful intent Incident response is an identificatio

Designing and coding of job search mechanism, Designing and coding of Job s...

Designing and coding of Job search mechanism: Project Title: FREEHIVE (Sep 2005- Nov 2006) Role             : Developer Domain         : Social Network Client

Develop a preliminary simulation model, Question: (a) State the strong ...

Question: (a) State the strong law of large numbers. (b) Data have been collected on response times (in minutes) at a fire station. The data are 2:7 1:8 0:8 1:4 1:2 (i

Distinguish between a mobile agent state and code, Question: (a) Disti...

Question: (a) Distinguish between a mobile agent "state" and "code". (b) Differentiate between "weak" and "strong" mobility. (c) Mobile agent systems are known to have

Computer security incident response team, QUESTION 1 Using a real life ...

QUESTION 1 Using a real life scenario or context list and set the scene for at least four advantages that an organized incident response program promotes. QUESTION 2 Yo

Public key cryptosystem based on rsa technology, Problem: (a) What is ...

Problem: (a) What is the minimum length of a password that could be considered to be "strong" in the context of today's computing power? (b) The security of a PIN system,

Biology, Ask question #Minimum 100 words are there non parasitic v...

Ask question #Minimum 100 words are there non parasitic viruses

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd