CCCrypt decrypting in AES CBC works even without IV

Question

I have a confusing problem, where decrypting a file which was encrypted using CCCrypt\'s AES-CBC mode with a randomized, 16byte IV produces the exact same output whether I p

Answer 1

The iv is only used for the first block on decryption, further blocks use the cipher text from the previous block so it is somewhat self-synchronizing.

Wikipedia image:

From Wikipedia Block cipher mode of operation.

So, picking up decryption in the middle of a CBC encrypted stream on a block boundary works except for the first block.