Re: [RFC][PATCH] Make cryptoapi non-optional?

Nick Piggin
2003-08-15T08:10:12Z

David S. Miller wrote:

>On Fri, 15 Aug 2003 09:30:03 +0200
>Andries Brouwer <aebr@win.tue.nl> wrote:
>
>
>>On Thu, Aug 14, 2003 at 06:17:13PM -0600, Val Henson wrote:
>>
>>
>>>entropy(x) >= entropy(x xor y)
>>>entropy(y) >= entropy(x xor y)
>>>
>>Is this trolling? Are you serious?
>>
>
>These lemma are absolutely true. XOR is the worst way
>to gain entropy because it means that if you are able
>to know anything about either 'x' or 'y' then you are
>able to know something about the resulting entropy.
>

_Either_ x or y? Surely not! 1 ^ ? = ? you still have 1
bit of entropy.