Re: When is the 'MyFamily' setting unnecessary?

[Gregory Maxwell <gmaxwell@xxxxxxxxx>]

On Mon, Sep 13, 2010 at 12:11 AM, Robert Ransom <rransom.8774@xxxxxxxxx> wrote:
>> There we goâ
>> Perhaps the signature could be shipped only to the directory
>> authorities but left out of the published descriptors, no?
> No, the client needs to see it in the relay/bridge descriptor.
>> they'd need to be left outside of the part signed by the nodes, so
>> obviously some reworking is required there).
> Why?

The client needs to see the public key for sure, since thats
effectively a family ID. Does it need to see the signature if instead
it trusts the bridges to have validated the signatures and correctly
ignored/invalidated only and all the nodes with invalid signatures?

If that was workable it would halve the amount of advertised data required.

> Don't forget that the keys and signatures would need to be represented
> in ASCII in the descriptors. ÂIf you're willing to break backward
> compatibility anyway, there is some room for squeezing the existing
> family specifications down, as well (i.e. represent node identity key
> fingerprints in base64, or even base85 (only the clients should care
> about it, and they can probably eat the performance cost)).

I was assuming hex, like the current families. 512/160=3.2  Obviously
base>16 would do even better... With smaller ecc and base85 it would
be rather close in size to the existing fingerprints. (assuming the
signature was omitted)

> Also, don't forget that we can use an elliptic curve modulo a 159-bit
> prime for this -- node family keys are relatively low-value
> authentication keys, and since they would only be used to sign nodes'
> ephemeral *signing* keys, they can be changed with rather little trouble.

Agreed, that they can be small. Though changing them would require
per-node configuration. They ought to at least be strong enough to
discourage mischief, though 159-bit is still harder than anything that
I'm aware of being cracked and would probably leave guessing the
secret as the low hanging fruit.
***********************************************************************
To unsubscribe, send an e-mail to majordomo@xxxxxxxxxxxxxx with
unsubscribe or-talk    in the body. http://archives.seul.org/or/talk/