Lecture 8 Flashcards
Cryptography: comes from ?
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Cryptology
Greek
Cryptography: Kryptos means ?
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Cryptology
hidden
Cryptography: Grahein means ?
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Cryptology
to write
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Process of making and using codes to secure the transmission of information
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Cryptology
Cryptography
?
Process of obtaining the original message form encrypted message
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Cryptology
Cryptanalysis
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Process of converting an original message into a form that is unreadable to unauthorized individuals
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Cryptology
Encryption
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Process of converting the encrypted message (cipertext) into an easily read message (plain text)
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Cryptology
Decryption
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Programmatic steps to encrypt message
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Cryptology - Basic Definitions
Algorithm
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Encryption method or process
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Cryptology - Basic Definitions
Cipher
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Encrypted message
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Cryptology - Basic Definitions
Ciphertext or cryptogram
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Process of converting unencrypted components into encrypted components
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Cryptology - Basic Definitions
Code
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Convert to plaintext
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Cryptology - Basic Definitions
Decipher
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To encrypt
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Cryptology - Basic Definitions
Encipher
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Information used with the algorithm to encrypt
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Cryptology - Basic Definitions
Key or crypto-variable
?
Entire range of values that can possibly be used to construct an individual key
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Cryptology - Basic Definitions
Key-space
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Series of encryptions /decryptions between a number of systems
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Cryptology - Basic Definitions
Link encryption
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The original message
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Cryptology - Basic Definitions
Plaintext or clear text
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Process of hiding messages
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Cryptology - Basic Definitions
Steganography
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Amount - effort required to perform cryptanalysis
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Cryptology - Basic Definitions
Work factor
? ??
(2) Cipher methods
Enumerate
Cryptology - Cipher methods
- Bit stream method
- Block cipher method
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Each bit in the plaintext is transformed bit by bit
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Cryptology - 1/2 Cipher methods 1/2 ?
Bit stream method
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Most common use XOR
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Cryptology - 1/2 Cipher methods 2/2 ?
Bit stream method
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Messaged divided into blocks
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Cryptology - 2/2 Cipher methods 1/3 ?
Block cipher method
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Each block is encoded
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Cryptology - 2/2 Cipher methods 2/3 ?
Block cipher method
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Substitution, transposition, XOR or combination
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Cryptology - 2/2 Cipher methods 3/3 ?
Block cipher method
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Substitute one value for another
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Cryptology - 1/3 ?
Substitution Cipher
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3 character substitution to the right
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Cryptology - 2/3 ?
Substitution Cipher
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Simple by itself – powerful when combined with other operations
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Cryptology - 3/3 ?
Substitution Cipher
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3 shift to the right is know as the ?
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Cryptology - Substitution Cipher
Caesar Cipher
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Implemented using the Vigenere Square
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Cryptology - 1/6 ?
Vigenere Cipher
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26 distinct cipher alphabets
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Cryptology - 2/6 ?
Vigenere Cipher
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Header row – normal order
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Cryptology - 3/6 ?
Vigenere Cipher
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Each additional row – shift right
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Cryptology - 4/6 ?
Vigenere Cipher
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Start in first row and find a substitution for one letter
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Cryptology - 5/6 ?
Vigenere Cipher
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Move down the rows for each subsequent letter of plaintext
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Cryptology - 6/6 ?
Vigenere Cipher
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Simply rearranges the values within a block
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Cryptology - 1/4 ?
Transposition Cipher
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Can be done at the bit level or the byte level
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Cryptology - 2/4 ?
Transposition Cipher
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Julius Caesar was associated with the early version of this cipher also
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Cryptology - 3/4 ?
Transposition Cipher
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Larger blocks or keys makes cipher stronger
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Cryptology - 4/4 ?
Transposition Cipher
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- Function of Boolean algebra
- Two bits are compared
- If identical, result is binary 0
- If not identical, result is binary 1
Identify
Cryptology - 1/2 ?
Exclusive OR (XOR)