Vanguards-Lite is meant for short-lived onion services such as OnionShare, as well as for onion client activity.

It is designed for clients and services that expect to have an uptime of no longer than 1 month.


Because it is for short-lived activity, its rotation times are chosen with the Sybil adversary in mind, using the max(X,X) skewed distribution.

We let NUM_LAYER2_GUARDS=4. We also introduce a consensus parameter guard-hs-l2-number that controls the number of layer2 guards (with a maximum of 19 layer2 guards).

No third layer of guards is used.

We don't write guards on disk. This means that the guard topology resets when tor restarts.

Rotation Period

The Layer2 lifetime uses the max(x,x) distribution with a minimum of one day and maximum of 22 days. This makes the average lifetime of approximately two weeks. Significant extensions of this lifetime are not recommended, as they will shift the balance in favor of coercive attacks.

From the Sybil Rotation Table, with NUM_LAYER2_GUARDS=4 it can be seen that this means that the Sybil attack on Layer2 will complete with 50% chance in 18*14 days (252 days) for the 1% adversary, 4*14 days (two months) for the 5% adversary, and 2*14 days (one month) for the 10% adversary.