LND has a configuration setting called time_lock_delta with the description "The required timelock delta for HTLCs forwarded over the channel.". I assume this to refer to some measure of time, but what is the unit of this value?

Screnshot of LND documentation

None of the four files in the LND repository that contain this string appear to mention the unit either.


The time_lock_delta is the minimum difference in the number of blocks between the CLTV of an incoming HTLC and the forwarded HTLC.

Full details are described in BOLT2 # CLTV expiry delta.


It seems to me that the field time_lock_delta in LND corresponds to what BOLT#7 refers to as cltv_expiry_delta. Which the specification explains to be "the number of blocks it will subtract from an incoming HTLC's cltv_expiry".

Hence, the unit would be a count of blocks.

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