You’re looking at a Dedication Transaction. Dedication transactions are submitted to the community by one channel proprietor to unilaterally shut a Lightning Community channel. The locktime in dedication transactions is used to speak channel state which leads to all dedication transactions being locked to a date in 1987.
Bolt3 specifies that dedication transactions retailer an obscured dedication transaction quantity (i.e. the “version” of the dedication) break up throughout the locktime and sequence fields. This makes it simpler for the channel proprietor to establish whether or not the most recent or an older dedication transaction was broadcast by the counterparty.
The dedication transaction quantity is just not saved in plaintext however obscured by XORing it with a shared secret created by hashing the concatenated payment_basepoint from the open_channel and accept_channel messages. For the reason that channel homeowners know these basepoints, they’ll revert the XOR to learn the encoded knowledge, however the knowledge seems pseudorandom to any third events.
In each the locktime and sequence, the higher byte is fastened, whereas the decrease three bytes every retailer three bytes of the obscured dedication transaction quantity. Within the locktime the higher byte should be set to 0x20, so the locktime of a dedication transaction should all the time fall in [0x20000000, 0x20ffffff], i.e.
53687091210 ≤
locktime≤ 55364812710
which can all the time leads to a time-based locktime to a date between 1987-01-05 and 1987-07-18.
