[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Exchange random numbers (was: Re: netscape's response)
-----BEGIN PGP SIGNED MESSAGE-----
Hello [email protected], [email protected], [email protected]
and Christian Wettergren <[email protected]>
Christian Wettergren <[email protected]> wrote:
...
> | If I only ever give out a hash of my seed, and only ever *add* any received
> | info to my seed (and stir it in well), how can anyone find out anything?
> | (Apart from hash weaknesses.)
>
> Giving out contribution:
> MD5(select_bits(my_seed, start_bit, stop_bit)) -> remote
> Taking in contribution :
> my_seed = my_seed XOR
> ((select_low_bits(remote_contrib, contrib_width) << contrib_area)
Hmm, I use:
taking-in:
seed = MD5(seed,new-data)
giving-out:
MD5(seed)
(where every giving-out is preceded by a taking-in). Is that OK?
If not, why not and how can I improve it?
> You also need to keep track of who has contributed what, and how much.
...
Why? I guess to keep track of how much entropy I believe I have...
> This might become a problem if you don't have a safe authentification
> mechanism, like baseing the tracking on the IP-numbers etc.
That's a safe authentication mechanism? I don't think so.
But you need a secrecy mechanism, so I guess that's where you'd
add your auth.
...
> The boot-strap stage is actually the big problem still. But if the
...
The boot-strap is done only once (at install time) so it's not a big
problem to ask for lots of random text from user.
...
> | In any case, accepting donations of entropy cannot possibly reduce the
> | amount of entropy I have, can it?
>
> This isn't a problem as I see it, he'll only know what bits he
> flipped, not the actual state.
Good, I thought so.
Sorry, have to go now, rest later...
Jiri
- --
<[email protected]> <[email protected]> PGP 463A14D5
-----BEGIN PGP SIGNATURE-----
Version: 2.6.2i
iQCVAwUBMGIpgixV6mvvBgf5AQGRggQAwEcY+5N0stTbWXfXg3zQ6FNdzv9Sckds
3xAjLbxr85jS98Sj0Nm++DwS674U8YfrNzTRg3HnOBUcS+i8UvP445jtj4UiyxU8
hyM2ZvzBWjFuj35jXF4KR5XotZyvAsAcICsssv0UQZ3JKWV+tU/pN8sZ3sgKRRWZ
ipvAFyY+rhA=
=1d8P
-----END PGP SIGNATURE-----