What are the block size, key size, and number of rounds used in DES encryption?

The correct answer identifies the characteristics of the Data Encryption Standard (DES), which is a symmetric key encryption algorithm widely used for data protection. In DES:

• The block size is 64 bits, meaning that the algorithm processes data in chunks of 64 bits at a time. This fixed size is crucial for the encryption and decryption processes, allowing DES to operate consistently with each data segment.

• The key size is 56 bits, which is the actual size of the key used to encrypt the data. Although keys are often represented as 64 bits, 8 bits are used for parity checks, reducing the effective key size to 56 bits. This means there are limited combinations available for key selection, affecting security.

• The algorithm operates in 16 rounds, which refers to the number of iterations the algorithm runs to increase encryption strength. Each round involves various operations, including substitutions and permutations, to transform the data further, contributing to the overall security of the encryption.

Understanding these specifications is fundamental to grasping how DES functions and its historical context in cryptographic practices, especially since its security has been challenged by advancements in computing power and cryptanalysis techniques.