Intro to Cryptography WGU C839 Module 2 Exam Questions with Correct Answers| Latest
Update Guaranteed Success
A random key is XOR'ed with a stream of plaintext.
Is sometimes called a state cipher, asynchronous stream cipher or ciphertext autokey (CTAK)
Symmetric Stream Ciphers
A stream of pseudo-random digits is generated independently. That stream of digits (called a
key stream) is combined with the plaintext (to encrypt) or the ciphertext (to decrypt)
Synchronous Stream Cipher
This method uses several of the previous N ciphertext digits to compute the key stream.
Self-synchronizing Stream Ciphers
Symmetric Stream Cipher
Most widely used software stream cipher
used identically for encryption and decryption as the data stream is XORed with the key.
has a variable key length from 1 to 256 bytes.
The resulting pseudo-random stream is XORed with the plaintext to produce the ciphertext
RC4
Symmetric Steam Cipher
Published by the German engineering firm Seimans in 1993
Is a software-based stream cipher that uses a Lagged Fibonacci generator with a concept
borrowed from the shrinking generator ciphers FISH
Symmetric Stream Cipher
Was published as an improvement on FISH
Identified how FISH was vulnerable to known plaintext attacks
, Is faster and stronger then FISH PIKE
Takes a variable-size input m and returns a fixed-size string (Digest)
Is expressed mathematically as h = H(m)
Said to be be one way if it is hard to invert, meaning computationally infeasible to find some
input x such that H(x) = h Hash Function
This refers to a situation where two different inputs yield the same output. A good has function
should not have any of these Collision
The input can be of any length
The output has a fixed length
H(x) is relatively easy to compute for any given x
H(x) is one-way
H(x) is collision-free Properties a good Hash function should include
In relation to hashing, this term refers to random bits that are used as one of the inputs to a
hash
This data complicates dictionary attacks that use pre-encrypted entries Salt
128 bit Hash Function specified by RFC 1321
Designed to replace MD4
Is not collision resistant MD5
Is a Hash function that uses a Merkle Tree-like structure to allow for immense parallel
computation of hashes for very long inputs.
Not ready to be a candidate for SHA-3 due to speed issues and other concerns MD6
Update Guaranteed Success
A random key is XOR'ed with a stream of plaintext.
Is sometimes called a state cipher, asynchronous stream cipher or ciphertext autokey (CTAK)
Symmetric Stream Ciphers
A stream of pseudo-random digits is generated independently. That stream of digits (called a
key stream) is combined with the plaintext (to encrypt) or the ciphertext (to decrypt)
Synchronous Stream Cipher
This method uses several of the previous N ciphertext digits to compute the key stream.
Self-synchronizing Stream Ciphers
Symmetric Stream Cipher
Most widely used software stream cipher
used identically for encryption and decryption as the data stream is XORed with the key.
has a variable key length from 1 to 256 bytes.
The resulting pseudo-random stream is XORed with the plaintext to produce the ciphertext
RC4
Symmetric Steam Cipher
Published by the German engineering firm Seimans in 1993
Is a software-based stream cipher that uses a Lagged Fibonacci generator with a concept
borrowed from the shrinking generator ciphers FISH
Symmetric Stream Cipher
Was published as an improvement on FISH
Identified how FISH was vulnerable to known plaintext attacks
, Is faster and stronger then FISH PIKE
Takes a variable-size input m and returns a fixed-size string (Digest)
Is expressed mathematically as h = H(m)
Said to be be one way if it is hard to invert, meaning computationally infeasible to find some
input x such that H(x) = h Hash Function
This refers to a situation where two different inputs yield the same output. A good has function
should not have any of these Collision
The input can be of any length
The output has a fixed length
H(x) is relatively easy to compute for any given x
H(x) is one-way
H(x) is collision-free Properties a good Hash function should include
In relation to hashing, this term refers to random bits that are used as one of the inputs to a
hash
This data complicates dictionary attacks that use pre-encrypted entries Salt
128 bit Hash Function specified by RFC 1321
Designed to replace MD4
Is not collision resistant MD5
Is a Hash function that uses a Merkle Tree-like structure to allow for immense parallel
computation of hashes for very long inputs.
Not ready to be a candidate for SHA-3 due to speed issues and other concerns MD6
