In encryption, when Cipher Block Chaining (CBC) is used, the Initialization Vector (IV) must be random and unpredictable. Otherwise, the encrypted value is vulnerable to crypto-analysis attacks such as the "Chosen-Plaintext Attack".

An IV value should be associated to one, and only one encryption cycle, because the IV's purpose is to ensure that the same plaintext encrypted twice will yield two different ciphertexts.

To that end, IV's should be:

* random
* unpredictable
* publishable (IVs are frequently published)
* authenticated, along with the ciphertext, with a Message Authentication Code (MAC)

This rule raises an issue when the IV is hard-coded.
