AES (Advanced Encryption Standard) is a symmetric encryption algorithm widely adopted worldwide. Unlike RSA, AES uses the same key for both encryption and decryption, making it much faster for large amounts of data. AES supports three key sizes: 128-bit, 192-bit, and 256-bit, with 256-bit providing the highest security level and being recommended for sensitive applications.
The choice of operation mode significantly affects security. CBC (Cipher Block Chaining) mode requires an Initialization Vector (IV) and provides better security by making identical plaintext blocks produce different ciphertext. ECB (Electronic Codebook) mode is simpler but less secure as it encrypts each block independently, potentially revealing patterns in the data. Always use CBC mode with a random IV for production applications.
AES encryption requires the plaintext length to be a multiple of the block size (16 bytes). The algorithm automatically applies PKCS#7 padding to handle messages of any length. When sharing encrypted data, both the key and IV (for CBC mode) must be securely transmitted to the recipient. Never reuse the same IV with the same key, as this can compromise security.