Ben Harris wrote:
2: Feed a counter through a one-way function (either a block cipher or a hash) to generate the nonce. This is more expensive (at least if you use a hash), but saves on network traffic and means that the sequence number is implicit in the nonce so that it need not be processed by Helix (though it may as well be, since doing so is cheap).
The obvious solution would be to use a separately keyed instance of Helix as a continuous PRNG. The PRNG seed (i.e. the second Helix key and nonce) could be the initial IV from the NEWKEYS.
-- Henrick Hellström www.streamsec.com