What is CBC?

CBC most commonly refers to Cipher Block Chaining. It is a mode of operation for block ciphers (like AES) that encrypts each block of plaintext by combining it with the previous ciphertext block. This makes the encryption of each block dependent on all prior blocks, enhancing security by preventing identical plaintext blocks from producing identical ciphertext blocks. It is frequently used in VPNs, TLS/SSL, and disk encryption.