Intro to Cryptography WGU C839 Module 5 Exam Solved 100% Correct!!

Finding any method to decrypt the message that is more efficient that simple brute force attempts. - Breaking Ciphers Simply trying every possible key to decrypt a message - Brute Force Using other techniques to attempt to derive the key, can be used to test the efficacy of a cryptographic algorithm. Frequently used to test hash algorithms for collisions. - Cryptanalysis The most basic tool for breaking classic ciphers like the Caesar and Vigenere Ciphers. Analysis the frequency of certain letters of the alphabet to derive some information about the key that was used. - Frequency Analysis This method is used for attacking polyalphabetic substitution ciphers, such as the Vigenere Cipher. Used to deduce the length of the keyword used in the polyalphabetic substitution, the longer ciphertext the more effective this method becomes. - Kasiski Method or Test The attacker obtains ciphertexts corresponding to the set of plaintexts of his own choosing. This is difficult but not impossible - Chosen Plaintext Attack The attacker only has access to a collection of ciphertexts. It is much more likely then a known plaintext attack, but is also the most difficult. This attack is completely successful if the corresponding plaintexts can be deduced, or the key. Obtaining any information about the underlying plaintext is still considered a success. - Chosen Ciphertext Only Like a chosen-plaintext attack, except the attacker can obtain ciphertext encrypted under two different keys. Very useful if you can obtain the plaintext and matching ciphertext. - Related-key Attack Based on finding affine approximations to the action of the cipher.Most commonly used on block ciphers. Known as a plaintext attack and uses linear approximations to describe the behavior of the block cipher. You can use this method to slowly re-create the key that was used. Eventually you will have an equation in the form of: Pi1 ⊕ Pi2 ⊕ . . . ⊕ Cj1 ⊕ Cj2 ⊕ . . . = Kk1 ⊕ Kk2 ⊕ . . . - Linear Cryptanalysis A form of cryptanalysis applicable to symmetric key algorithms The examination of differences in an input and how that input affects the resultant differences in output. Originally worked only with chosen plaintext, could also work with known plaintext and ciphertext only - Differential Cryptanalysis This attack in particularly useful against block ciphers. Based on substitution-permutation networks, an extension of differential cryptanalysis. - Integral Cryptanalysis Cryptanalysis Resource The number of primitive operations which much be performed. Could be basic computer instructions like addition, XOR, shift or even entire encryption methods - Time Cryptanalysis Resource The amount of storage required to perform the attack - Memory