Cryptography Reference
In-Depth Information
6. The introduction point passes this information on to the hid-
den server who then decides whether to complete the key ex-
change and meet at the rendezvous point.
7. Assuming the hidden server likes Alice's request, it will set up
its own tunnel to the rendezvous point and tell the rendezvous
point that it wants to communicate with Alice. Well, it won't
know Alice by name. It will only know Alice's pseudonym.
8. The rendezvous point will notify Alice that the hidden server
wants to talk too.
9. Alice completes the key negotationwith the hidden service and
she now has a secure link to the hidden server without knowing
who the hidden server happens to be.
This entire exchange is a bit like the kind of negotiation that
teenagers use in courting when asking their friends to find out if so-
and-so likes me. If the entire onion network is trustworthy, the link is
trustworthy too. The rendezvous point doesn't know the identity of
either the client (Alice) or the server because the layers of proxies in
between hide this information. Also, the introductory server and the
directory server won't know the hidden server because the layers of
proxies hid the sender during the initiation. The directory server just
knows that there's some hidden server out there with a name and an
identity.
Still, this has limitations. Imagine someone decides to operate
a hidden server
good-stuff.onion
. Once the name becomes known
andpassedaroundamongpeople,there'snoeasywayfortheoriginal
owner of
good-stuff.onion
to prevent someone else from setting up
shop and broadcasting the name to directory servers. How will the
directory server know which is the rightful owner of the name? If the
battles over domain services are brutal when privacy isn't involved,
they're close to impossible when it's not possible to identify people.
One solution is to tie the identity to some public key not a domain
name like
good-stuff.onion
.Onlythepersonwhocreatedtheorig-
inal key pair should be able to lay claim to this public key later. The
onlyproblemisthatthiskeyisnotaseasytorememberasthesimple
domain name
good-stuff.onion.
This problem can be reduced but not eliminated if the directory
servers have a long memory and maintain long, stable connections
with the onion routing network. They can link the domain name
with the public key when the entry is created and as long as they
honor this link, the network will be able to find one and only one
