Outline Chapter 8 - Outline Chapter 8 Is the process of...

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Outline Chapter 8 Encryption Is the process of converting an original message into a form that is unreadable to unauthorized individual, that is to anyone without the tools to convert the encrypted message back to its original format. 351 Decryption Is the process of converting the ciphertext message back into plaintext so that it can be readily understood. 351 Cryptography, Cryptology 350 History of Cryptology 351 Algorithm The programmatic steps used to convert an unencrypted message into an encrypted sequence of bits that represent the message; sometimes refers to the programs that enable the cryptographic processes. 354 Cipher or cryptosystem An encryption method or process encompassing the algorithm, key(s) or cryptovariable(s), and procedures used to perform encryption and decryption. Ciphertext or cryptogram Encoded message resulting from an encryption Code The process of converting components (words or phrases) of an unencrypted message into encrypted components Decipher To decrypt or convert ciphertext into the equivalent plaintext Encipher To encrypt or convert plaintext into the equivalent ciphertext Key or cryptovariable The information used in conjunction with an algorithm to create the ciphertext from the plaintext or derive the plaintext from the ciphertext, the key can be a series of bits used by a computer program, or it can be a passphrase used by humans that is then converted into a series of bits used by a computer program. Keyspace The entire range of values that can be used to construct an individual key Link encryption A series of encryption and decryptions between a number of systems, wherein each system in a network decrypts the message sent to it and then reencrypts it using different keys and sends it to the next neighbor, and this process continues until the message reaches the final destination. Plaintext or cleartext The original unecrypted message, or a message that has been successfully decrypted Steganography The hiding of messages, for example, within the digital encoding of a picture or graphic Work factor The amount of effort (usually in hours) required to perform crypt-analysis to decode an encrypted message when the key or algorithm (or both) are unknown. Cryptosystems Are made up of a number of elements or components- algorithms, data handling techniques, and procedures and process steps, which are combined in multiple way to ensure confidentiality and provide authentication and authorization for business processes. 354 Cipher Methods The are two methods of encrypting plaintext: The bit stream method or the block cipher method. 354 Bit stream method Each bit in the plaintext is transformed into a cipher bit one bit at a time. Bit stream methods commonly use algorithm like the exclusive OR operation (XOR). 354
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This note was uploaded on 03/15/2012 for the course CIS CIS120 taught by Professor Zales during the Spring '12 term at Harrisburg Area Community College.

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Outline Chapter 8 - Outline Chapter 8 Is the process of...

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