[Cryptography] updating a counter

[Ben Laurie]

On 19 May 2014 18:26, John Denker <jsd at av8n.com> wrote:
> My favorite thing is to use a collection of subcounters.
>
> Most of the subcounters are LFSRs.  Some of them shift
> left, and some of them shift right.  Between the shifting
> and the XORing, a lot of bits get changed.
>
> Each subcounter gets updated every time.  I arrange for
> the periods to be relatively prime, so that the period
> of the collection is the product of the periods of the
> individual subcounters.

Hmm. That's surely not sufficient to ensure it doesn't repeat values.
Which matters.