[Cryptography] [Crypto-practicum] Justify the sequence of operations in CTR mode.

[Jerry Leichter]

> Hmmm.  What happens if we use a cipher that takes a key 64 bits larger
> than really required to achieve security - say 180 to 256 bits - and
> the key used to encrypt any particular block is the salt (disk sector)
> plus the user's 128-bit secure key?
You're re-inventing tweakable block ciphers.  See https://www.cs.berkeley.edu/~daw/papers/tweak-crypto02.pdf

                                                        -- Jerry