[hashcash] Re: BCC problem (was: Hi!)

On Fri, 26 May 2006 18:39:53 +0200, Máté Soós <msoos@xxxxxxxxxxxxxx> said:

> The problem with BCC, as far as I can see, is that the X-HASH value
> must contain the email address of the BCC recipient, which needs to be
> hidden. In theory, we could use some sort of masking of this email
> address. And if we are at hashes, why not use them (after all, they
> are one-way, not only 2nd-preimage-resistant). So, hash the address,
> and use that(or some first bytes of that) instead of the email
> string. ...

One problem with that is that it breaks things such as catch-all
addresses.  e.g. (almost) all addresses @uhoreg.ca will reach me.  For
example, you could write mail to hubertisamoron@... and it will be
delivered to me.  But then I won't have any way of checking whether or
not there is a valid hashcash token for my address, because I don't know
what address you used to mint the stamp.

Hubert

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