[tor-dev] Time interval for changing Introduction Points in Tor Hidden Services

[David Goulet]

On 23 Mar (09:57:50), Piyush Kumar Sharma wrote:
>  Thank you David for the prompt reply. The information you provide is
> helpful.
> 
> I would also like to ask one more question related to HSDIRs.
> From what I understand from the onion service v3 specification, the HSDIRs
> corresponding to a particular hidden service change every 24 hours.
> This is achieved with the help of a shared random variable (SRV) advertised
> in the network consensus, which is changed after every 24 hours.
> 
> So my question is: If all the HSDIRs corresponding to a hidden service go
> down (for some reason), can the hidden service somehow change it's HSDIRs
> before the 24 hours epoch? Or does it mean that as soon as the HSDIRs are
> inaccessible, the hidden service corresponding to them cannot be accessed
> before the next epoch?

They are not pinned to an immutable set of HSDir but rather the location in
the hashring of where to start picking HSDirs is decided by the SRV.

In other words, HSDirs are picked up by proximity of that location on the
hashring. If all HSDirs go down, the service will simply pick the next ones on
the hashring (closer to the location).

A bit like if the location needs to be 0xAAAA and the closer HSDir is 0xAAAB.
If that one goes down, tor will select the next one let say at 0xAAAC, and so
on..

The tor code does re-upload descriptors to any new/changing HSDir on the
hashring (if any) upon receiving a new consensus.

Cheers!
David

-- 
bO2GGRweZied5CndmqgrdYdQYdSDW6hcScOCr/c8Xig=
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: not available
URL: <http://lists.torproject.org/pipermail/tor-dev/attachments/20220323/f5e5dcbc/attachment.sig>