Which key size is not supported by AES encryption?

AES (Advanced Encryption Standard) supports three specific key sizes: 128 bits, 192 bits, and 256 bits. These key lengths are crucial for the security level of AES encryption, with the longer key sizes generally providing higher security against brute-force attacks.

The key size of 512 bits is not supported by AES. In fact, AES was designed to operate efficiently with the specified key lengths while balancing security and performance. Having a 512-bit key would not only be unnecessary but could also lead to performance issues without significantly increasing security due to the existing strengths of the supported key lengths.

This understanding of AES is essential in cryptography, as it highlights the importance of using established standards for encryption to ensure robust security while maintaining efficiency.