cryptography and network security by atul khare pdf download
Posts: 8,059
Threads: 1
Joined: Mar 2014
cryptography and network security by atul khare pdf download
Cryptography
! Cryptography is the study of " Secret (crypto-) writing (-graphy)
! Concerned with developing algorithms:
" Conceal the context of some message from all except the sender and recipient (privacy or secrecy), and/or " Verify the correctness of a message to the recipient (authentication)" Form the basis of many technological solutions to computer and communications security problems
CS595-Cryptography and Network Security
Basic Concepts
! 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
! Plain text
" The original intelligible message ! Cipher text
" The transformed message CS595-Cryptography and Network Security
Basic Concepts
! Cipher
" An algorithm for transforming an intelligible message into unintelligible by transposition and/or substitution
! Key
" Some critical information used by the cipher, known only to the sender & receiver
! Encipher (encode)
" The process of converting plain text to cipher text
! Decipher (decode)
" The process of converting cipher text back into plain text CS595-Cryptography and Network Security
Basic Concepts
! Cryptanalysis
" The study of principles and methods of transforming an unintelligible message back into an intelligible message without knowledge of the key. Also called codebreaking
! Cryptology
" Both cryptography and cryptanalysis
! Code
" An algorithm for transforming an intelligible message into an unintelligible one using a code-book
Security
! Two fundamentally different security " Unconditional security
# No matter how much computer power is available, the cipher cannot be broken " Computational security
# Given limited computing resources (e.G time needed for calculations is greater than age of universe), the cipher cannot be broken