D334 Introduction to Cryptography - Set 4 - Part 2

Correct Answer: To issue and manage digital certificates

A Certificate Authority (CA) is responsible for issuing, managing, and validating digital certificates, which are used to verify the identity of parties in secure communications.

Correct Answer: AES

AES is considered the most secure symmetric encryption algorithm, offering strong encryption with key sizes of 128, 192, and 256 bits.

Correct Answer: Replay attack

In a replay attack, the attacker captures valid data transmissions and reuses them at a later time to gain unauthorized access.

Correct Answer: SHA-256

SHA-256 is a cryptographic hash algorithm that generates a fixed-length hash value, ensuring data integrity.

Correct Answer: It verifies the identity of the sender and the integrity of the message

A digital signature verifies the identity of the sender and ensures that the message has not been tampered with during transmission.

Correct Answer: Asymmetric encryption

Asymmetric encryption uses different keys for encryption and decryption, typically a public key for encryption and a private key for decryption.

Correct Answer: AES

AES is a symmetric block cipher that encrypts data in fixed-size blocks using the same key for both encryption and decryption.

Correct Answer: Side-channel attack

A side-channel attack exploits weaknesses in the physical implementation of encryption, such as timing, power consumption, or electromagnetic leaks, to deduce the encryption key or other sensitive information.

Correct Answer: 128 bits

AES has a fixed block size of 128 bits, regardless of the key length used in the encryption process.

Correct Answer: The attacker decrypts a message by trying all possible keys

A brute-force attack involves trying all possible keys until the correct key is found to decrypt the ciphertext.

Correct Answer: 256 bits

AES-256 uses a 256-bit key for encryption, providing a higher level of security than AES-128 or AES-192.

Correct Answer: It ensures data integrity by producing a fixed-length output from a variable-length input

Hashing ensures data integrity by producing a unique, fixed-length hash value from a variable-length input, allowing verification that the data has not been altered.

Correct Answer: ECB

In Electronic Codebook (ECB) mode, identical plaintext blocks produce identical ciphertext blocks, making it vulnerable to pattern analysis attacks.

Correct Answer: It ensures that a session key is not reused in future sessions

Forward secrecy ensures that session keys are not reused in future sessions, providing additional security by preventing compromise of past communications.

Correct Answer: RSA

RSA is based on the mathematical difficulty of factorizing large prime numbers, which forms the basis of its security.

Correct Answer: It allows for faster encryption and decryption

Symmetric encryption algorithms like AES are generally faster than asymmetric algorithms because they use the same key for both encryption and decryption.

Correct Answer: It requires secure key distribution

The main disadvantage of symmetric encryption is the need for secure key distribution between parties, as both must use the same key.

Correct Answer: It uses a small key size

DES has a small key size of 56 bits, which makes it vulnerable to brute-force attacks.

Correct Answer: RSA

RSA is commonly used in HTTPS for securing web traffic, as it provides strong encryption for key exchanges and digital signatures.

Correct Answer: Brute-force attack

In a brute-force attack, the attacker tries every possible key until the correct one is found to decrypt the ciphertext.