Cryptography Concepts

Question 1

Define Synchronous Encryption

Answer 1

encryption / decryption occurs immediately

Question 2

Define Asynchronous Encryption

Answer 2

encryption / decryption requests are processed from a queue. A delay can take place

Question 3

Define Symmetric Encryption

Answer 3

same key used to encrypt and decrypt

Question 4

Define Asymmetric Encryption

Answer 4

One private key and one public key perform encryption and decryption

Question 5

Define Digital Signature

Answer 5

method of providing sender authentication and message integrity.

message acts as input to hash function

sender’s private key encrypts the hash value

hash computation on received message determines validity of the message

Question 6

Define hash

Answer 6

one way function that reduces message to a hash value

Comparison of sender’s hash value to receiver’s hash value determines message integrity

Question 7

Define ciphertext

Answer 7

altered form of message that is unreadable without knowing the key and encryption system used

aka cryptogram

Question 8

Define cryptosystem

Answer 8

components that make encryption possible:

algorithm
key
key management system

Question 9

Define cryptanalysis

Answer 9

science of decrypting ciphertext without prior knowledge of the key or crypto system used

aka breaking encryption

Question 10

Define key clustering

Answer 10

Occurs when different encryption keys generate same ciphertext from same plaintext message

considered a weakness of an algorithm if they occur frequently

Question 11

Define keyspace

Answer 11

all possible key values when using particular algorithm or other security measure

Question 12

Define collision

Answer 12

when a hash function produces same hash value on different messages

considered a weakness of an algorithm if they occur frequently

Question 13

Define algorithm

Answer 13

mathematical function that encrypts and decrypts data

aka a cipher

Question 14

Define cryptology

Answer 14

science that studies encrypted communications and data

Question 15

Define Encoding

Answer 15

process of changing data into another form using code

Question 16

Define Transposition

Answer 16

process of shuffling or reordering the plaintext to hide the original message

aka permutation

Question 17

Define Substitution

Answer 17

process of exchanging 1 byte in a message for another

Question 18

Define Confusion

Answer 18

process of changing a key value during each round of encryption

confusion is often carried about by substitution

Question 19

Define Diffusion

Answer 19

process of changing location of the plaintext within the cypher text

often carried out during transposition

Question 20

Define Avalanche Effect

Answer 20

Condition in which any change in the key or plaintext no matter how minor significantly changes the ciphertext

Question 21

Define Work Factor

Answer 21

Amount of time and resources needed to break encryption

Question 22

Define one-way function

Answer 22

mathematical function that can be more easily performed in one direction than the other

Question 23

Define Trapdoor

Answer 23

secret mechanism that allows the implementation of the reverse function in a one-way function

Question 24

Cryptographic Life Cycle

Answer 24

implementation

maintenance

retirement / replacement