[tor-relays] descriptor-id calc tool?

[Ivan Markin]

On Thu, Mar 02, 2017 at 01:11:00PM +0000, nusenu wrote:
> nusenu:
> > Shouldn't the first 2 or 3 hex digits of your output (after converting
> > them to hex) without time option and the actual intro point FPs match
> > when run at roughly the same time?
> > 
> > example for duckduckgo:
> > 
> > ./get-intro-points.py 3g2upl4pq6kufc4m  [1]
> > 3g2upl4pq6kufc4m:56782537778BEFC5A48080B58BE01E814AF9B5D3
> > 3g2upl4pq6kufc4m:769DBA4C0C992FCEA080618833FD7BF5AC1F4F41
> > 3g2upl4pq6kufc4m:744B753C7F5E0C6BDD240EE5D879A36C650D2B00
> > 
> > 
> > go run descriptor-id-calc.go 3g2upl4pq6kufc4m
> > replica #0: sv5uuknuqvjgquf4hu4m6tvcyuyiyvw7
> > -> hex: 957B4A29B485526850BC3D38CF4EA2C5308C56DF
> > 
> > replica #1: crpc4lkarusgflm5nblslpopg5qpvw7i
> > -> hex: 145E2E2D408D2462AD9D685725BDCF3760FADBE8
> > 
> > they start with 95.. and 14.. but the actual intro points start with
> > 56.., 76.. and 74.. ?
> 
> I probably misunderstood how the design works.
> 
> The introduction points are not chosen by calculating the descriptor-id
> and finding the 3 HSDirs next to it (by sorted fingerprint).

tldr: HSDir != IntroPoint.

Introduction points are chosen by random by an onion service and unknown 
in advance. What is known in advance is only the onion address. Descriptor ID
determines which HSDirs are responsible for storing corresponding descriptor.
List of the current IntroPoints are embedded into descriptor (that's the
reason we have descriptor thing in the first place).

--
Ivan Markin