How to make IvParameterSpec random but still decrypt

Question

For Encryption in Java... the article at http://cwe.mitre.org/data/definitions/329.html states that the Initialization Vector should be different each time, but if I use a different IV to decrypt than the one I used to encrypt, I get garbage characters instead of the data I expected.

What is the proper way to encrypt on one server and decrypt on another without having to communicate the IV back and forth in between servers?

The common technique seems to be to hardcode a byte array, but supposedly that's insecure???

Answer 1

I believe an IV is like a salt - it's not a secret, it's just used to introduce an extra element of randomness so that the same message encrypted with the same key still comes out differently each time.

So you can transmit the IV used to encrypt as part of the encrypted value, just like you'd store the salt along with a hash for a hashed value.

Of course, I could be completely incorrect...