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Ch08 - Scrambling Through Cryptography

# Ch08 - Scrambling Through Cryptography - S...

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Scrambling Through Cryptography Security+ Guide to Network Security Fundamentals  Second Edition Chapter 8:

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2 Objectives Define cryptography Secure with cryptography hashing algorithms Protect with symmetric encryption algorithms Harden with asymmetric encryption algorithms Explain how to use cryptography
3 Cryptography Terminology Cryptography: science of transforming information so it is  secure while being transmitted or stored Steganography: attempts to hide existence of data Encryption: changing the original text to a secret message  using cryptography Decryption: reverse process of encryption Algorithm: process of encrypting and decrypting information  based on a mathematical procedure Key: value used by an algorithm to encrypt or decrypt a  message

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4 Cryptography Terminology (continued) Weak key: mathematical key that creates a detectable pattern  or structure Plaintext: original unencrypted information (also known as  clear text) Cipher: encryption or decryption algorithm tool used to create  encrypted or decrypted text Ciphertext: data that has been encrypted by an encryption  algorithm
5 Cryptography Terminology (continued)

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6 How Cryptography Protects Intended to protect the confidentiality of information Second function of cryptography is authentication Should ensure the integrity of the information as well Should also be able to enforce nonrepudiation, the inability to  deny that actions were performed Can be used for access control
7 Securing with Cryptography Hashing  Algorithms One of the three categories of cryptographic algorithms is  known as hashing

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8 Defining Hashing Hashing, also called a one-way hash, creates a ciphertext from  plaintext Cryptographic hashing follows this same basic approach Hash algorithms verify the accuracy of a value without  transmitting the value itself and subjecting it to attacks A practical use of a hash algorithm is with automatic teller  machine (ATM) cards
9 Defining Hashing (continued)

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10 Defining Hashing (continued) Hashing is typically used in two ways: To determine whether a password a user enters is correct  without transmitting the password itself To determine the integrity of a message or contents of a file Hash algorithms are considered very secure if the hash that is  produced has the characteristics listed on pages 276 and 277 of  the text
11 Defining Hashing (continued)

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12 Message Digest (MD) Message digest 2 (MD2) takes plaintext of any length and  creates a hash 128 bits long  MD2 divides the message into 128-bit sections If the message is less than 128 bits, data known as padding
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Ch08 - Scrambling Through Cryptography - S...

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