This chapter presents the following content: Models for network (access) security, classical encryption techniques, symmetric cipher model, have considered, classical cipher techniques and terminology, brute force, cryptanalysis of brute force, caesar cipher, cryptanalysis of caesar cipher. | Data Security and Encryption (CSE348) Lecture slides by Lawrie Brown for “Cryptography and Network Security”, 5/e, by William Stallings, briefly reviewing the text outline from Ch 0, and then presenting the content from Chapter 1 – “Introduction”. Lecture # 3 Review Security concepts: confidentiality, integrity, availability Security attacks, services, mechanisms Models for network (access) security Classical Encryption Techniques Symmetric Cipher Model Chapter 1 summary. Some Basic Terminology plaintext - original message ciphertext - coded message cipher - algorithm for transforming plaintext to ciphertext key - info used in cipher known only to sender/receiver encipher (encrypt) - converting plaintext to ciphertext decipher (decrypt) - recovering ciphertext from plaintext cryptography - study of encryption principles/methods cryptanalysis (codebreaking) - study of principles/ methods of deciphering ciphertext without knowing key cryptology - field of both cryptography and cryptanalysis Briefly review some terminology used throughout the course. Symmetric Cipher Model Detail the five ingredients of the symmetric cipher model, shown in Stallings Figure : plaintext - original message encryption algorithm – performs substitutions/transformations on plaintext secret key – control exact substitutions/transformations used in encryption algorithm ciphertext - scrambled message decryption algorithm – inverse of encryption algorithm Cryptanalytic Attacks ciphertext only only know algorithm & ciphertext, is statistical, know or can identify plaintext known plaintext know/suspect plaintext & ciphertext chosen plaintext select plaintext and obtain ciphertext chosen ciphertext select ciphertext and obtain plaintext chosen text select plaintext or ciphertext to en/decrypt Stallings Table summarizes the various types of cryptanalytic attacks, based on the amount of information known to the cryptanalyst, from least to most. | Data Security and Encryption (CSE348) Lecture slides by Lawrie Brown for “Cryptography and Network Security”, 5/e, by William Stallings, briefly reviewing the text outline from Ch 0, and then presenting the content from Chapter 1 – “Introduction”. Lecture # 3 Review Security concepts: confidentiality, integrity, availability Security attacks, services, mechanisms Models for network (access) security Classical Encryption Techniques Symmetric Cipher Model Chapter 1 summary. Some Basic Terminology plaintext - original message ciphertext - coded message cipher - algorithm for transforming plaintext to ciphertext key - info used in cipher known only to sender/receiver encipher (encrypt) - converting plaintext to ciphertext decipher (decrypt) - recovering ciphertext from plaintext cryptography - study of encryption principles/methods cryptanalysis (codebreaking) - study of principles/ methods of deciphering ciphertext without knowing key cryptology - field of both .
