Re: [GNUnet-developers] Re: URI suggestion

[Marcos D. Marado Torres]

Couldn't the keys be generated using (also) an handle, so that each public key
has a nickname associated to it?

Mind Booster Noori

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Marcos Daniel Marado Torres AKA Mind Booster Noori
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On Tue, 23 Sep 2003, Christian Grothoff wrote:

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> On Monday 22 September 2003 07:25 pm, Glenn McGrath wrote:
> > On Mon, 22 Sep 2003 21:45:09 +0300 (EEST)
> >
> > Igor Wronsky <address@hidden> wrote:
> > > Another thing that would be of practical value would
> > > be the possibility to address a namespace by just a
> > > human-readable pseudonym. I couldn't come up with a
> > > neat crypto trick for that yet, but atleast it should
> > > be kludgable.
> >
> > An optional alias could be attached somehow to the namespace, the
> > obvious concern is collisions, i.e. two seperate namesapces want to use
> > the same alias.
>
> Right.  The key question is who is allowed to put forward that association.
> If I can insert a global handle for my own namespace, I could (maliciously)
> pick the alias of someone else who is popular and try to impersonate that
> pseudonym. For users that use the aliases (and that don't see the underlying
> public keys), this attack would succeed.  GNUnet could not tell which was the
> "original" alias / handle and prevent it.
>
> > Alias wouldnt be the primary identifier, so collisions wouldnt be a
> > problem.
>
> If they are to be useful for the end-users, they'd likely become the primary
> identifiers...
>
> > Handle it the same way instant messangers do it.
>
> Eh, don't they just assume that the "first" person to take an alias gets to
> keep it? In a distributed P2P setting (IMs are centralized!), we can't do
> that.
>
> I have another idea. Why not *generate* shorter aliases from the public key.
> That is, you can not pick your alias, but there is a (deterministic)
> projection from your public key / pseudonym ID to a slightly more readable
> string.  An adversary that would want to take over a pseudonym would then
> have to find a public key that computes to a pseudonym ID that collides with
> the target ID.  Ok, given that the strings are likely to have less than 160
> bits of information, computing that collision may be *easier* than getting a
> collision on the RIPE160MD hash, but we could pick the IDs long enough to
> make it reasonably difficult.
>
> I have some example PHP code that computes "almost natural language" passwords
> in the same way that I picture us computing more natural pseudonym aliases:
>
> >>>> from BNT <<<<
> $syllables="er,in,tia,wol,fe,pre,vet,jo,nes,al,len,son,cha,ir,ler,bo,ok,tio,nar,sim,ple,bla,ten,toe,cho,co,lat,spe,ak,er,po,co,lor,pen,cil,li,ght,wh,at,the,he,ck,is,mam,bo,no,f
> i,ve,any,way,pol,iti,cs,ra,dio,sou,rce,sea,rch,pa,per,com,bo,sp,eak,st,fi,rst,gr,oup,boy,ea,gle,tr,ail,bi,ble,brb,pri,dee,kay,en,be,se";
>   $syllable_array=explode(",", $syllables);
>   srand((double)microtime()*1000000);
>   for ($count=1;$count<=4;$count++) {
>     if (rand()%10 == 1) {
>       $makepass .= sprintf("%0.0f",(rand()%50)+1);
>     } else {
>       $makepass .= sprintf("%s",$syllable_array[rand()%62]);
>     }
>   }
>
>
> Replace the PRNG with the hash (or initialize it with the hash), avoid
> duplicate syllables and this one gives you 32 bit aliases. Changing 4 to say
> 6 gives use 48 bit which should be sufficiently collision resistant
> (considering that each test requires computing an RSA public/private key pair
> and that the adversary typically wants to force a collision with a specific
> pseudonym).  The resulting aliases woudl look like "ralenerdeekayse", which
> is probably easier for our brains to associate with values like "good
> content" or "garbage" than the currently used
> "0B0C955A9196DAF1D55F6E337FD93DC75FE8B488".
>
> Christian
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