Note that the data sent from Alice to En is encrypted with a key only they share, rendering this attack impossible. On Dec 17, 2011 11:25 AM, "Daniel Cohen" <[email protected]> wrote:
> Hi, > > I am new to Tor, but after reading about its design, and reading a few > research papers on its vulnerabilities (specifically timing attacks), I had > the following thought: > > Suppose Alice is connecting to Bob via Tor, using HTTPS encryption. She > sends a packet to the Tor entry node (call it En). The packet travels > through the network, emerges from an exit node (call it Ex), and arrives at > Bob. > > Alice => En => Tor Network => Ex => Bob > > Now suppose that Alice's connection is being monitored, as well as a group > of the exit nodes (which are either hostile or having their packets > sniffed). When the encrypted packet leaves Alice on its way to En, it is > sniffed, and a checksum is made of its encrypted payload. The packet then > continues through the network as usual, and emerges from an exit node. > > It appears to me that the attacker need only check packets coming out of > exit nodes to see if their payload checksums match that of the packet > observed leaving Alice. Unlike timing attacks, which require a reasonable > number of packets to confirm Alice's identity, this attack would require > only one, since checksums have an almost 0% chance of collision. If a > packet with the same payload checksum as Alice's is discovered, it almost > certainly originated from her. > > Is this a problem with Tor's architecture? If so, has this issue already > been addressed? > > Thanks, > > Daniel Cohen > > _______________________________________________ > tor-dev mailing list > [email protected] > https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev > >
_______________________________________________ tor-dev mailing list [email protected] https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev
