M2: Cryptographic building blocks - C2

Question 1

What is encryption?

M2: Cryptographic building blocks - C2

Answer 1

Turning readable data into a secret code to keep it safe.

Question 2

What is decryption?

M2: Cryptographic building blocks - C2

Answer 2

Turning the secret code back into readable data.

Question 3

What is symmetric-key encryption?

M2: Cryptographic building blocks - C2

Answer 3

Using the same key to both encrypt and decrypt data.

Question 4

What is public-key encryption?

M2: Cryptographic building blocks - C2

Answer 4

Using a public key to encrypt data and a private key to decrypt it.

Question 5

What is a digital signature?

M2: Cryptographic building blocks - C2

Answer 5

A unique tag added to a message to verify the sender’s identity.

Question 6

What is a cryptographic hash function?

M2: Cryptographic building blocks - C2

Answer 6

A function that converts data into a fixed-size string of characters which appears random.

Question 7

What is message authentication?

M2: Cryptographic building blocks - C2

Answer 7

Ensuring that a message comes from a legitimate source and hasn’t been altered.

Question 8

What is authenticated encryption?

M2: Cryptographic building blocks - C2

Answer 8

Combining encryption and authentication to protect data confidentiality and integrity.

Question 9

What is a certificate?

M2: Cryptographic building blocks - C2

Answer 9

A digital document that verifies the ownership of a public key.

Question 10

What is the Vernam cipher?

M2: Cryptographic building blocks - C2

Answer 10

An encryption method using a key as long as the message known for being unbreakable if used correctly.

Question 11

What is a one-time pad?

M2: Cryptographic building blocks - C2

Answer 11

A type of Vernam cipher where the key is used only once and is as long as the message.

Question 12

What is a block cipher?

M2: Cryptographic building blocks - C2

Answer 12

An encryption method that processes data in fixed-size blocks.

Question 13

What is a stream cipher?

M2: Cryptographic building blocks - C2

Answer 13

An encryption method that processes data one bit or byte at a time.

Question 14

What is the Advanced Encryption Standard (AES)?

M2: Cryptographic building blocks - C2

Answer 14

A widely used block cipher for securing data.

Question 15

What is the Caesar cipher?

M2: Cryptographic building blocks - C2

Answer 15

An ancient encryption technique that shifts letters by a fixed number of places.

Question 16

What is exhaustive key search?

M2: Cryptographic building blocks - C2

Answer 16

Trying all possible keys until the correct one is found.

Question 17

What is a passive adversary?

M2: Cryptographic building blocks - C2

Answer 17

An attacker who only observes and records data without altering it.

Question 18

What is an active adversary?

M2: Cryptographic building blocks - C2

Answer 18

An attacker who can alter data or inject new data into the communication.

Question 19

What is a known-plaintext attack?

M2: Cryptographic building blocks - C2

Answer 19

An attack where the adversary has access to both the plaintext and its ciphertext.

Question 20

What is a chosen-plaintext attack?

M2: Cryptographic building blocks - C2

Answer 20

An attack where the adversary can choose the plaintext and see the resulting ciphertext.

Question 21

What is a chosen-ciphertext attack?

M2: Cryptographic building blocks - C2

Answer 21

An attack where the adversary can choose the ciphertext and see the resulting plaintext.

Question 22

What is the Electronic Codebook (ECB) mode?

M2: Cryptographic building blocks - C2

Answer 22

A block cipher mode where each block is encrypted independently.

Question 23

What is the Cipher Block Chaining (CBC) mode?

M2: Cryptographic building blocks - C2

Answer 23

A block cipher mode where each block of plaintext is XORed with the previous ciphertext block before being encrypted.

Question 24

What is the Counter (CTR) mode?

Answer 24

A block cipher mode that turns a block cipher into a stream cipher by encrypting a counter value.

Question 25

What is a hybrid encryption? ## Footnote M2: Cryptographic building blocks - C2

Answer 25

Using public-key encryption to share a symmetric key which is then used for encrypting the actual message.

Question 26

What is RSA encryption? ## Footnote M2: Cryptographic building blocks - C2

Answer 26

A public-key encryption method based on the difficulty of factoring large numbers.

Question 27

What is data origin authentication? ## Footnote M2: Cryptographic building blocks - C2

Answer 27

Verifying who sent a message.

Question 28

What is data integrity? ## Footnote M2: Cryptographic building blocks - C2

Answer 28

Ensuring that data has not been altered.

Question 29

What is non-repudiation? ## Footnote M2: Cryptographic building blocks - C2

Answer 29

Ensuring that a sender cannot deny sending a message.

Question 30

What is a collision in hash functions? ## Footnote M2: Cryptographic building blocks - C2

Answer 30

When two different inputs produce the same hash value.