Which of the following cryptographic algorithms is an example of symmetric encryption and employs a block cipher with a key size of up to 256 bits?

The Advanced Encryption Standard (AES) is a symmetric encryption algorithm widely regarded for its strength and efficiency. AES uses a block cipher to encrypt data in fixed-size blocks of 128 bits, supporting key sizes of 128, 192, or 256 bits. As a symmetric encryption method, AES employs the same key for both encryption and decryption, ensuring data confidentiality during transmission. AES is highly secure due to its robust key schedule and resistance to cryptanalysis techniques. It is used in various applications, including secure file transfer, VPNs, and SSL/TLS protocols. The algorithm’s speed and reliability make it the encryption standard for organizations like the U.S. government. Why Other Options Are Incorrect: 1. RSA: RSA is an asymmetric encryption algorithm, which uses a key pair (public and private) for encryption and decryption. 2. ECC: Elliptic Curve Cryptography is also asymmetric, providing security through mathematical curves. 3. DES: Data Encryption Standard is symmetric but outdated due to its limited key size (56 bits), making it vulnerable to brute-force attacks. 4. Diffie-Hellman: This is a key exchange protocol, not an encryption algorithm. AES stands out due to its balance of security and performance, making it the preferred symmetric encryption algorithm.