I am aware of the Paul Kocher single known plaintext attack (13
bytes or more) on the stream cipher used to password protect ZIP
archives.
Are there any other practical attacks (~1 hour on modest hardware)
against the cypher if the password is presumed to have sufficient
entropy.
I
Every finite field F is a finite abelian
group under addition, and so has a minimal annihilator or characteristic
p which must be prime with the property that a + ... + a
(p times)
= 0 for every element a of
F. So
-a = a + ... + a (p-1 times).
Now this is supposed to be hard to compute.
We
You posit the difficulty of obtaining additive inverses,
this would suggest that they need to exist, and you likely want addition
to be commutative, so you at least have a ring.
What actual algebraic properties do you need?
The possible choices from most specialized to least specialized (that
