Definition of Cryptography

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Cryptography is the study of mathematical techniques related to aspects of information security such as confidentiality, data integrity, entity authentication, and data origin authentication. Cryptography is not the only means of providing information security, but rather one set of techniques. An easy way to comply with the conference paper formatting requirements is to use this document as a template and simply type your text into it :

1.      Confidentiality is a service used to keep the content of information from all but those authorized to have it.

2.      Data Integrity is a service which addresses the unauthorized alteration of data.

3.      Authentication is a service related to identification. This function applies to both entities and information itself.

4.      Non-repudiation is a service which prevents an entity from denying previous commitments or actions

It provides a schematic listing of the primitives considered and how they relate. These primitives should be evaluated with respect to various criteria such as:

A. Level of Security This is usually difficult to quantify.

B. Functionality Primitives will need to be combined to meet various information security objectives.

C. Methods of Operation Primitives, when applied in various ways and with various inputs, will typically exhibit different characteristics;

D. Performance This refers to the efficiency of a primitive in a particular mode of operation. 

E. Ease of Implementation This refers to the difficulty of realizing the primitive in a practical instantiation.

Cryptography, over the ages, has been an art practiced by many who have devised ad hoc techniques to meet some of the information security requirements. Public key cryptography is also an option when it comes to encryption but it requires excessive communication and processing resources. There are several algorithms that can be categorized as classical but out of many  will be shedding some light on 3 such techniques :

A. Caesar Cipher is a classical substitution cipher, and one of the simplest example of substitution cipher  which replaces the letter of alphabet with a letter that is 3 paces ahead of it , for example “ZULU” will be converted in to “CXOX”.

B. Vigenere Cipher when compared with Caesar gives some level of security with the introduction of a keyword; this key word is repeated to cover the length of the plain text that is to be encrypted example is shown below: 

C. Playfair Cipher Another example of classical cipher is Playfair cipher that has a square of matrix of 5X5 alphabetic letters arranged in an appropriate manner.

Several modern encryption techniques exist but here it will focus on two variants of Data Encryption Standard one is DES other is S-DES.

A.    S-DES Simplified-DES has a process of key generation instead of using key as it is for encryption and decryption the key generation process of S-DES generates 2 sub keys after processing the initial 10 bit input.

B.     DES enhances the structure of S-DES by increasing the key size from 10-bits to 64-bits out of which its affective length is 56-bits.

Avalanche effect is the phenomenon that describes the effect in the output cipher text if a single or few bits are changed in the plain text. This change that occurs at the output should be sufficient if we want to create a secure algorithm. Encryption Algorithms are considered essential in any secure communication environment. Several encryption techniques are proposed in this regard, one of the recent techniques talks about an algorithm that have surpassed DES, S-DES, Vigenere and Playfair algorithm in terms of Avalanche Effect,  in they compared their proposed idea with the above mentioned techniques and found that the proposed technique. The Avalanche Effect is 45 bits, 70.31% [14] as compared to DES (35 bits, 54.6%), S-DES (5 bits, 7.8%), Playfair (7 bits, 10.9%), Vigenere (2 bits, 3.1%) [2], Caesar (1 bit, 1.56%) [8], Blowfish (19 bits, 28.71%), Proposed (42 bits, 65.6%). This review showed that in terms of avalanche effect the worst technique is Caesar that gives a difference of 1 bit similarly it is seen that Vigenere giving better results than Caesar by giving a difference of 2 bits, it is also seen that Playfair giving better results than Vigenere by giving a difference of 7 bits DES that uses 16 rounds gave 35 bit difference and proposed  gave 42 bits difference when a single character was changed and for the same sample the proposed technique gave an avalanche effect of 45 bits hence it concludes that this technique was superior to the ones mentioned and compared in this review paper.

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Posted by Samini on Monday, 17 July 2017 - Rating: 4.5

Title : Definition of Cryptography
Description : Cryptography is the study of mathematical techniques related to aspects of information security such as confidentiality, data integrity, en...

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