According to information in this LND PR the sender of an
TemporaryChannelFailure can be determined:
In many cases it is impossible for the sender to determine which of the two nodes in a pair is responsible for the failure. In this situation, we now penalize bidirectionally. This does not hurt the good node of the pair, because only its connection to a bad node is penalized.
So my understanding of this comment is, the channel, or at least the node next to one of the exhausted channels can be identified quite easily. Is it really that easy? Can
TemporaryChannelFailure and therefore channel exhaustions always be assigned to two nodes or one channel?
I always assumed, the error cannot be assigned to a node or channel at all.
This might simplify the work of some papers, such as On the Difficulty of Hiding the Balance of Lightning Network Channels by J Herrera-Joancomarti et al., or open new attack vectors.
Edit: more links for further research
In case someone wants to give a more in-depth answer or do research on top of this, here are some links to the code in the
lnd client github code base:
In lightningnetwork/lightning-onion crypto.go, function
DecryptError, the client cycles through the secrets to unwrap the error and identify the
In lightningnetwork/lnd htlcswitch/switch.go, function
DecryptErrorfunction is used to access the failure.
Later this value will be accessed e. g. in