For this question, I'm going to introduce a new mode of operation,
which is very similar to cipher feedback mode.
This is the way cipher feedback mode worked.
The change for output feedback mode
is instead of taking the cipher text
and putting that back into the x vector,
we're going to take the output from the encryption
and take that, so that's the only difference between
cipher feedback mode and output feedback mode.
Which of the following are true?
Output feedback mode provides stronger protection against tampering
than is possible with CFB.
Unlike CFB, with OFB it's possible to recover most of an encrypted file,
even if one of the blocks in the encrypted file is lost.
Like CFB, it could be the basis of  a cryptographic hash function using OFB.
And finally, it would be safe to use 0 as the initialization vector for OFB.
Which of the following 4 statements are true?
