Section 21: Hashing and Symmetric Algorithms

Question 1

HMAC

Answer 1

Hash Based Message Authentication Code

▪ Combines a cryptographic hash of the message with a secret key shared by the sender and receiver.

▪ Reduces collisions due to the addition of unique outputs

Question 2

Message Authentication Code (MAC)

Answer 2

▪ Confirms the stated identity of the sender and provides integrity of the message without the need to use any other means

Similar concept to digitally signing an email or code signing an application.

Question 3

Stream Cipher

Answer 3

Combines a stream of plaintext bits or bytes with a pseudorandom
stream initialized by a secret key

Encryption is performed one bit at a time. or one byte at a time

Very good for encrypting live audio and video since it is continuous

Message: 1234
Key: ABCD

1A2B3C4D

Question 4

Block Cipher

Answer 4

▪ Breaks input into fixed-length blocks of data and then performs
encryption on each block

● Easy implementation
● More secure