AES encrypts data in blocks of how many bits?

AES, or Advanced Encryption Standard, is a widely used symmetric encryption algorithm. It encrypts data in blocks of 128 bits. This block size is fixed and applies to all versions of the AES algorithm, whether it uses different key lengths of 128, 192, or 256 bits.

The choice of 128 bits for the block size is significant because it provides a high level of security and efficiency in encryption operations. Encrypting data in blocks of 128 bits allows the algorithm to handle data in manageable chunks, which aligns well with modern hardware capabilities. Additionally, this block size has been subjected to considerable security analysis, making it a robust choice that has gained widespread acceptance in various security standards.

In contrast, the other options listed (64 bits, 256 bits, and 512 bits) do not represent the block size used by AES. For example, a block size of 64 bits is characteristic of older encryption algorithms like DES (Data Encryption Standard), while 256 bits refers to one of the key sizes available for AES, not its block size. The incorrect options can thus be ruled out based on their inapplicability to the AES specification.