What is the primary function of a Block Cipher?

The primary function of a block cipher is to encrypt fixed-size chunks of data at a time. This means that data is processed in blocks of a predetermined size, typically ranging from 32 bits to 256 bits, depending on the specific algorithm being used. When plaintext is fed into a block cipher, it divides the data into these fixed-size blocks and then applies cryptographic transformations to each block using an encryption key, ensuring that even if the same block of plaintext is encrypted multiple times, the resulting ciphertext can be different when different keys are used.

This fixed-size characteristic is fundamental to how block ciphers operate because it allows for structured and predictable operations, making it easier to design secure encryption algorithms and analyze their strengths and vulnerabilities. The design of block ciphers, such as AES (Advanced Encryption Standard), is specifically centered around this principle, reinforcing the importance of fixed-size data processing in secure encryption practices.