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

Structure of a typical frame relay, Problem a) Consider a 1000 Mbps Eth...

Problem a) Consider a 1000 Mbps Ethernet with a single Store-N-Forward switch mid-way in the path between two nodes A and B. Assume that there are no other nodes on the network

Calculate the false rejection, Divide the user data into 6 equal sets. Use ...

Divide the user data into 6 equal sets. Use the first set for the enrollment phase of your system, and the rest for the verification phase. Use the following formula to calculate t

Network security, Network security has become much more complex than ever b...

Network security has become much more complex than ever before. New types and sources of network security threats, always-on high-speed Internet connections, wireless networking, a

Network-based ids (nids), Network-Based IDS (NIDS) A NIDS resides on com...

Network-Based IDS (NIDS) A NIDS resides on computer or appliance connected to segment of an organization’s network and looks for signs of attacks. While examining packets, a NID

Transmision imparment, What are Transmission Impairments? Explain the follo...

What are Transmission Impairments? Explain the following concepts with respect to Transmission Impairments a) Attenuation b) Delay Distortion c) Noise ion #Minimum 100 words ac

Explain how the diffie-hellman key agreement protocol works, (a) Using Fer...

(a) Using Fermat's theorem, find 3 201 mod 11. (b) Explain how the Diffie-Hellman key agreement protocol works and what its purpose and main properties are. Consider a Dif

Social studies, how would land elevation have canged if coronado had travel...

how would land elevation have canged if coronado had traveled 150 miles due west from what is today arizona instead of west toward new mexico

Collision detection, COLLISION DETECTION The signals from two devices ...

COLLISION DETECTION The signals from two devices will interfere with each other and the overlapping of frames is known a collision. It does not cause to the hardware but data

Software vulnerabilities, 1.  We used the National Vulnerability Database. ...

1.  We used the National Vulnerability Database. Select a recent vulnerability from that Database and analyse it from the following aspects: Criticality level Impact in

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