On Oct 24, 2008, at 14:29, John Denker wrote:

On 09/29/2008 05:13 AM, IanG wrote:My assumptions are: * I trust no single source of Random Numbers. * I trust at least one source of all the sources. * no particular difficulty with lossy combination.If I have N pools of entropy (all same size X) and I pool them together with XOR, is that as good as it gets?Yes. The second assumption suffices to prove the result, since (random bit) XOR (anything) is random.

`Ah, but for this to hold, you will also have to assume that the N`

`pools are all independent. If they are not, you cannot even guarantee`

`one single bit of "entropy" (whatever that is). For example, if N =`

`2, your trusted source is pool 1, and I can read pool 1 and control`

`pool 2, I set pool 2 = pool 1, and all you get is zeros. And that`

`surely does not contain X bits of "entropy" for any reasonable`

`definition of "entropy".`

Fun, Stephan --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]