What is the block size of AES?

What is the block size of AES?

• A. 64-bit
• B. 32-bit
• C. 128-bit
• D. 256-bit

Answer: (C)

AES processes data in 128-bit blocks, and this fixed block size applies across all key lengths (128, 192, and 256). The block size determines how much plaintext is handled in one go and interacts with padding and the mode of operation used to encrypt larger messages. A 128-bit block helps reduce the chance of repeating blocks and patterns when encrypting long data streams, which improves security for typical usage. In contrast, smaller block sizes like 64-bit or 32-bit would lead to more frequent block reuse and potential leakage of structure in modes such as CBC or CFB, especially with long messages. The idea of a much larger block size, such as 256-bit, isn’t part of the AES specification. So the defined and standard block size for AES is 128 bits.

AES processes data in 128-bit blocks, and this fixed block size applies across all key lengths (128, 192, and 256). The block size determines how much plaintext is handled in one go and interacts with padding and the mode of operation used to encrypt larger messages. A 128-bit block helps reduce the chance of repeating blocks and patterns when encrypting long data streams, which improves security for typical usage. In contrast, smaller block sizes like 64-bit or 32-bit would lead to more frequent block reuse and potential leakage of structure in modes such as CBC or CFB, especially with long messages. The idea of a much larger block size, such as 256-bit, isn’t part of the AES specification. So the defined and standard block size for AES is 128 bits.