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

Security services, (a) Mention the five main security services. (b) What...

(a) Mention the five main security services. (b) What is a passive attack? Give an example of passive attack? (c) What four types of active attacks and mention their respecti

Intrusion detection and classification, i want to detec and classify networ...

i want to detec and classify network anomaly detection based on KDD99 data set using swarm intelligence

What is b-router, B-Router Hybrid devices that has the features of bot...

B-Router Hybrid devices that has the features of both routers and bridges . A bridge router or brouter is a network machine that acts as a router and as a bridge. The brout

Explain security, W h a t do you understand by the terms security, netwo...

W h a t do you understand by the terms security, network security and information security? How network security and information security are connected? Security can be def

Elliptic curve encryption - decryption scheme, (a) (i) If m = p·q·r where...

(a) (i) If m = p·q·r where p, q, and r are prime numbers, what is Φ(m)? (ii) Therefore, Determine Φ(440). (b) Describe the following terms as used in cryptography: (i)

Nyquist capacity theorem, (a) Illustrate what you understand by Nyquist Cap...

(a) Illustrate what you understand by Nyquist Capacity Theorem? (b) Consider we wish to transmit at a rate of 64 kbps over a 4 kHz noisy but error-free channel. What is the mini

Using icmp reachability, USING ICMP TO TEST REACHABILITY:  ICMP can a...

USING ICMP TO TEST REACHABILITY:  ICMP can also be used to test several tools. An Internet host A, is reachable from another host B, if data packets can be send from A to B. P

Algorithm, algorithm on simple intrest

algorithm on simple intrest

Who are the individuals who cause these security problems, Who are the indi...

Who are the individuals who cause these security problems? Many unauthorized people who cause network security problems for obtaining information about the other users and causi

Information and network security, Information and Network Security Part ...

Information and Network Security Part 1- Recovery of an encrypted `word' using a forward search attack. Complete and correct summary for part 1. Adequately commented, clea

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