initialization vector (redirected from Initialisation vector)

A continuously changing number used in combination with a secret key to encrypt data. Initialization vectors (IVs) are used to prevent a sequence of text that is identical to a previous sequence from producing the same exact ciphertext when encrypted. For example, packets have address fields that are generally fixed in location within the header of the packet. If attackers view the same encrypted data over and over, it provides them with clues to interpret their original values. See nonce.