Random initialization Vector (IV) with Cipher Block Chaining (CBC) Mode algorithm

[GokhanArik]

byte[] iv = new byte[writer.getBlockSize()];

I was told that we should use random number for iv size. Do you confirm that? What should be limits of the random size?

[sveinungkb]

The IV is hashed with SHA-256, so regardless of what you pass in it will be 256 bits which is the entropy size for the IV for this AES configuration.