[Cryptography] Bloom filter question

[John Levine]

It appears that Peter Fairbrother <peter at tsto.co.uk> said:
>But I do have some concerns about your threat model. Bloom filters are 
>not designed for secrecy or concealment.
>
>For instance, if you only have one item in the filter it is going to be 
>pretty sparse, and easily recognisable as a single item. Do you need 
>dummy items? A nonce? A secret to add pre-hash?

It's not a big deal.  If there's only one recipient, it's usually obvious
from other things who it was and if there's more than one, you can usually
tell that, too, even if you can't tell who the other ones are.

I suppose if it were an issue, we could add dummy items that don't
have @ signs so they can't collide with real addresses.


R's,
John