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

TCP/IP v OSI, What are the main differences between TCP/IP vs OSI?

What are the main differences between TCP/IP vs OSI?

Ids deployment overview, IDS Deployment Overview The decision regarding ...

IDS Deployment Overview The decision regarding control strategies, decisions about where to locate elements of intrusion detection systems is an art in itself. Planners should s

Network security keys, The three primary types of network protection are th...

The three primary types of network protection are the same as the three primary areas where a network can be attacked. Every network needs protection against people-related, hardwa

Explain the purpose of the dr and bdr, QUESTION a) Compare and contras...

QUESTION a) Compare and contrast between static and dynamic routing. b) What are the merits (five merits) and limitations (3 limitations) of using Open Shortest Path First

Issue specific security policy, Why an organization need the issue specific...

Why an organization need the issue specific security policy

Find the capacity of the wcdma, Question: (a) Describe the term interfe...

Question: (a) Describe the term interference in the space, time, frequency, and code domain. (b) Consider a 1 G - AMPS: 824-849 MHz (forward) ; 869-894 MHz (reverse). B

Explain what is a broadcast storm, QUESTION: (a) Ethernet has grown in ...

QUESTION: (a) Ethernet has grown in popularity in the recent years and is now used in LANs. Give three reasons for the success behind Ethernet. (b) Ethernet uses the CSMA/CD

Network, what is computer network?

what is computer network?

Selecting a risk control strategy, Selecting a Risk Control Strategy Risk...

Selecting a Risk Control Strategy Risk controls involve selecting one of the 4 risk control strategies for every vulnerability. The flowchart is shown in the figure given below

Understanding a business model of a spammer, The first and foremost need of...

The first and foremost need of  any business is a role to perform for its client base, and for the spammer this will typically be the role of advertising products which, due to the

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