[Standards-JIG] Re: The Great Encryption Debate

Ian Paterson ian.paterson at clientside.co.uk
Tue Aug 9 19:54:07 UTC 2005

> This isn't really a problem, since in the method I proposed only  
> requires that they exchange hashes (something like MD5 or SHA) of  
> each JID.  There is no way of getting the JID back from the hash, so  
> there is no way of using this to discover even the partial contents  
> of someone's roster unless you have a mutual acquaintance.

Yes. But if Alice wanted to know if Charlie was in Bob's roster then she
could simply propose a chat and send him the hash of Charlie's JID
(whether Charlie is really on her roster or not doesn't matter).

> Since writing this, I have become familiar with the web of trust  
> concept employed by CAcert.  This allows individuals to assure  
> others, which might be a slightly better model.  I would have to
> a bandwidth analysis of this...

I really like your idea... but, as you hinted, the scheme could consume
a frightening amount of bandwidth. If the TTL allowed 4 hops and an
average roster includes 32 people, then up to one million requests would
be made!

If all Alice's contacts asked all their contacts (and it stopped there),
then up to 1000 requests would still be required.

Again there is a privacy issue. Alice would have to disclose the fact
that she was starting a trust relationship with Bob to all her contacts.

> Alice and Bob can ask other mutual acquaintances to sign their keys,  
> giving a greater trust-score to each other. The trust score 
> should be inversely proportional to distance between people and 
> proportional to the number of trusted paths between individuals.

That's interesting too.

- Ian

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