OFB is specified as having an IV instead of a Nonce.

https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Output_feedback_.28OFB.29
ModeWithNonce is no longer used.
ModeWithNonce no longer exists.
OFB uses an initialization vector instead a nonce.
Merge pull request #60 from dreid/ofb-iv-not-nonce

OFB uses an IV instead of a nonce.