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

Example of an attack against a windows, The objective of this example is to...

The objective of this example is to demonstrate the steps required for a successful attack against a vulnerable Windows XP SP2 system. It will show: a) how Nessus can be used to di

Netfilter firewall, Netfilter Firewall Netfilter is the popular name f...

Netfilter Firewall Netfilter is the popular name for the packet filtering system installed by default in the Linux kernel. The filtering system can be used as a very effective

Using Technology as Experience Framework, Write a two to three (2-3) page p...

Write a two to three (2-3) page paper in which you: Explain how the Web user interfaces help donors to make decisions. Relate the emotional thread demonstrated in the case study to

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

Meaning of dns - domain name system, What do you understand by the DNS? Exp...

What do you understand by the DNS? Explain the usage of the resource rec or ds. Domain Name System is described below: The Domain Name Service (DNS) is the hierarchi

Explain symmetric and asymmetric encryption system, Question 1: (a) Dif...

Question 1: (a) Differentiate between symmetric and asymmetric encryption system. (b) Describe how a digital signature is created. (c) Explain briefly what SSL (secure so

Discuss the influence the commercial operations, Question: A regional p...

Question: A regional police force has the following corporate objectives: ? to reduce crime and disorder; ? to promote community safety; ? to contribute to delivering just

What is triple key management scheme, Q. What is Triple Key Management Sche...

Q. What is Triple Key Management Scheme? The triple key management mechanism provides optimum security by enabling the use of two pre-deployed keys for each of the WS nodes, an

Tracing a route, There is another probing methods i-e Trace Route. To get m...

There is another probing methods i-e Trace Route. To get more detail it is used     As given in the figure about the route to DANDELION-PATCH.MIT.EDU was looked out a

Develop a tcp-based client-server socket program, Develop a TCP-based clien...

Develop a TCP-based client-server socket program for transferring a large message. The message transmitted from the client to server is read from a large file (size is about 30000

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