Opened 4 years ago

Last modified 2 years ago

#16646 new defect

Cannibalized intro point circuits are now 4 hops, instead of 3 (HS-side)

Reported by: asn Owned by:
Priority: Medium Milestone: Tor: unspecified
Component: Core Tor/Tor Version: Tor: 0.2.7
Severity: Normal Keywords: tor-hs, performance, research, prop247, tor-hs
Cc: Actual Points:
Parent ID: Points:
Reviewer: Sponsor:

Description

The fix of #16260 makes hidden services establish a 4-hop introduction circuit, if they cannibalized during introduction circuit construction.

This was done mainly to prevent circuit fingerprinting according to the latest USENIX paper, but it's unclear whether making only this change helps with anything.

Hence, the performance penalty of 4-hops might be more important here.

Another question, is how often do introduction circuits get cannibalized? It might be that it often happens, since this step is done in the very beginning when there are a few internal circuits lying around. But I might be very wrong.

Child Tickets

Change History (13)

comment:1 Changed 4 years ago by dgoulet

Keywords: TorCoreTeam201508 added

comment:2 Changed 4 years ago by nickm

Keywords: TorCoreTeam201508 removed
Milestone: Tor: 0.2.???

comment:3 Changed 4 years ago by nickm

Keywords: SponsorR removed
Sponsor: SponsorR

Bulk-replace SponsorR keyword with SponsorR sponsor field in Tor component.

comment:4 Changed 4 years ago by dgoulet

Milestone: Tor: 0.2.???Tor: 0.2.8.x-final
Points: small

comment:5 Changed 4 years ago by teor

Are we also worried about cannibalized 4-hop rendezvous circuits?
(I think I have them the right way around, it's been a week since I've looked at the code.)

comment:6 in reply to:  5 Changed 4 years ago by dgoulet

Replying to teor:

Are we also worried about cannibalized 4-hop rendezvous circuits?
(I think I have them the right way around, it's been a week since I've looked at the code.)

If I understand correctly your question, you cannot cannibalized a *non* General Purpose Circuit so it's not possible to get a 4-hop circuit with a rdv purpose.

comment:7 Changed 4 years ago by nickm

Milestone: Tor: 0.2.8.x-finalTor: 0.2.???

It is impossible that we will fix all 277 currently open 028 tickets before 028 releases. Time to move some out. This is my first pass through the "new" and "reopened" tickets, looking for things to move to ???.

comment:8 Changed 4 years ago by dgoulet

Severity: Normal
Sponsor: SponsorRSponsorR-can

comment:9 Changed 3 years ago by teor

Milestone: Tor: 0.2.???Tor: 0.3.???

Milestone renamed

comment:10 Changed 3 years ago by nickm

Keywords: tor-03-unspecified-201612 added
Milestone: Tor: 0.3.???Tor: unspecified

Finally admitting that 0.3.??? was a euphemism for Tor: unspecified all along.

comment:11 Changed 2 years ago by nickm

Keywords: tor-03-unspecified-201612 removed

Remove an old triaging keyword.

comment:12 Changed 2 years ago by dgoulet

Keywords: research added
Points: small
Sponsor: SponsorR-can

comment:13 Changed 2 years ago by nickm

Keywords: prop247 added
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