Cryptographic Tools and Security

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What is the key length used in Data Encryption Standard (DES)?

256-bit
56-bit (correct)
128-bit
64-bit

Which algorithm was selected as the Advanced Encryption Standard (AES) in 2001?

RSA
Rijndael (correct)
Triple-DES
Data Encryption Standard (DES)

What is the purpose of Message Authentication Codes?

To provide separate authentication mechanisms.
To protect against active attacks and verify the authenticity of received messages. (correct)
To ensure timely delivery of messages.
To encrypt the contents of the message.

What type of encryption uses a single key for both encryption and decryption?

Symmetric encryption (D) Signup and view all the answers

What is the main concern regarding the Data Encryption Standard (DES)?

Use of a 56-bit key (B) Signup and view all the answers

What are the potential weaknesses of symmetric encryption and how do attackers exploit them?

Potential weaknesses of symmetric encryption include reliance on the nature of the algorithm and some knowledge of plaintext characteristics, as well as the possibility of brute-force attacks. Attackers exploit these weaknesses through cryptanalysis, which involves deducing specific plaintext or keys by exploiting characteristics of the algorithm, or by attempting exhaustive key searches. Signup and view all the answers

What are the differences between Data Encryption Standard (DES) and Triple-DES?

DES uses a 64-bit plaintext block and a 56-bit key to produce a 64-bit ciphertext block, while Triple-DES repeats the basic DES algorithm three times using either two or three unique keys. Triple-DES is considered much more secure but also slower compared to DES. Signup and view all the answers

What were the key criteria considered by NIST when selecting the Advanced Encryption Standard (AES)?

NIST considered efficiency, security, hardware/software suitability, and the key lengths of 128, 192, and 256 bits when selecting the Advanced Encryption Standard (AES) in 2001. Signup and view all the answers

How does Message Authentication protect against active attacks, and what are the key requirements for Message Authentication Codes (MAC)?

Message Authentication protects against active attacks by verifying that the received message is authentic and unaltered from the authentic source and is timely and in the correct sequence. The key requirements for Message Authentication Codes include the ability to be applied to any size data and to produce a fixed-length output. Signup and view all the answers

What is the significance of the selection of Rijndael as the symmetric block cipher for Advanced Encryption Standard (AES)?

Rijndael was selected for its efficiency, security, and suitability for both hardware and software implementations. It uses 128-bit data and supports key lengths of 128, 192, and 256 bits, making it widely available commercially as the chosen symmetric block cipher for AES. Signup and view all the answers