Sunday, 13 November 2016

Some Terms of Network Security

Basic Concepts :

1)Cryptography :The art or science encompassing the principles and methods of transforming an intelligible message into one that is unintelligible, and then retransforming that message back to its original form.

2)Key :Some critical information used by the cipher, known only to the sender& receiver.

3)Plaintext :The original intelligible message. 

4)Cipher text :The transformed message. 

5)Cipher :An algorithm for transforming an intelligible message into one that is unintelligible by transposition and/or substitution methods.

6)Encipher (encode) :The process of converting plaintext to cipher text using a cipher and a key.

7)Decipher (decode) :The process of converting cipher text back into plaintext using a cipher and a key.

8)Code :An algorithm for transforming an intelligible message into an unintelligible one using a code-book.

9)Cryptanalysis :The study of principles and methods of transforming an unintelligible message back into an intelligible message without knowledge of the key. Also called code breaking. 

10)Cryptology :Both cryptography and cryptanalysis.

11)Symmetric-key cryptography refers to encryption methods in which both the sender and receiver share the same key (or, less commonly, in which their keys are different, but related in an easily computable way). This was the only kind of encryption publicly known until June 1976.

The Data Encryption Standard (DES) and the Advanced Encryption Standard (AES) are block cipher designs that have been designated cryptography standards by the US government (though DES's designation was finally withdrawn after the AES was adopted).Despite its deprecation as an official standard, DES (especially its still-approved and much more secure triple-DESvariant) remains quite popular; it is used across a wide range of applications, from ATM encryption to e-mail privacy and secure remote access. Many other block ciphers have been designed and released, with considerable variation in quality. Many have been thoroughly broken, such as FEAL. Symmetric key ciphers are implemented as either block ciphers or stream ciphers. A block cipher enciphers input in blocks of plaintext as opposed to individual characters, the input form used by a stream cipher.

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