Chpt 6 Flashcards
What are the 4 goals of cryptography?
Confidentiality
Integrity
Authentication
Nonrepudiation
What does this symbol mean in Boolean mathematics?
AND
Tests whether two values are both true.
What does this symbol mean in Boolean mathematics?
v
OR
This checks to see whether at least one of the input values is true.
What does this symbol mean in Boolean mathematics?
~ or !
NOT
This simply reverses the value of an input variable.
What does this symbol mean in Boolean mathematics?
+ in a O
XOR or Exclusive OR
This returns the true value when only one of the input values is true.
I.e. if both values are false or both are true, the output of XOR is false (0).
What is the Modulo function?
The remainder value left over after a division operation is performed.
Represented by %
What is a Work Function?
A measure of the strength of a cryptography system. A measure of the effort in terms of cost/time to perform a complete brute force attack.
Define Confusion in Cryptography
When the relationship between the plaintext and the key is so complicated that an attacker can’t merely continue to alter the plaintext and analyzing the ciphertext to determine the key.
Define Diffusion in Cryptography
When a small change in the plaintext results in a big change in the ciphertext.
What the bit block size of AES?
128-bit
Which ciphers often use a passage from a commonly available book as a key?
Running Key or Book Ciphers
Which algorithm uses prewhitening and postwhitening?
Twofish algorithm
What is the equation for finding the number of keys needed in symmetric ciphers?
n(n-1) / 2
What cannot be achieved by secret key cryptography?
Nonrepudiation
