[tor-dev] Proposal: Merging Hidden Service Directories and Introduction Points

[George Kadianakis]

Michael Rogers <michael at briarproject.org> writes:

> On 12/07/15 22:48, John Brooks wrote:
>> 1.3. Other effects on proposal 224
>> 
>>    An adversarial introduction point is not significantly more capable than a
>>    hidden service directory under proposal 224. The differences are:
>> 
>>      1. The introduction point maintains a long-lived circuit with the service
>>      2. The introduction point can break that circuit and cause the service to
>>         rebuild it
>
> Regarding this second difference: the introduction point (cooperating
> with a corrupt middle node) could potentially try to discover the
> service's guard by repeatedly breaking the circuit until it was rebuilt
> through the corrupt middle node. Would it make sense to use vanguards
> here, as well as on rendezvous circuits?
>

Hello,

currently we address this intro point guard discovery attack by having hidden
services retry only 3 times. After those 3 times, they ditch that intro point
and pick another one.

That said proposal 247 suggests that hidden services use vanguards for both
rendezvous and introduction point circuits anyway.

Take care!