A process used to hide patterns of identical blocks of data within a packet. An Initialization Vector (an initial random number) is used as the first random block to encrypt and decrypt a block of data. Different random blocks are used in conjunction with the secret key to encrypt each block.
(CBC) A method of operating a symmetric block cipher that uses feedback to combine previously generated ciphertext with new plaintext. Each plaintext block is combined with the ciphertext of the previous block by a bitwise- XOR operation before it is encrypted. Combining ciphertext and plaintext ensures that even if the plaintext contains many identical blocks, they will each encrypt to a different ciphertext block. When the Microsoft Base Cryptographic Provider is used, CBC is the default cipher mode.
An encryption method that protects against block replay attacks by making the encryption of a cipher block dependent on all blocks that precede it; it is designed to make unauthorized decryption incrementally more difficult. Oracle Advanced Security employs outer cipher block chaining because it is more secure than inner cipher block chaining, with no material performance penalty.
CBC is a mode in which every plaintext block encrypted with a block cipher is first exclusive-ORed with the previous ciphertext block (or, in the case of the first block, with the initialization vector). For decryption, every block is first decrypted, then exclusive-ORed with the previous ciphertext block (or IV).