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I am learning about lighting now and I'm trying to check my understanding on-chain w/ a block explorer. I have opened several channels already and closed some also.

I would like to confirm my understanding of the script logic (e.g. the 2-of-2 multisig, the HTLCs, and the conditional refunds) as described in the lightning white paper and other sources.

Unfortunately the block explorers I have tried only show "OP_0 " under the Pkscript fields for these transactions, Blockchain.com for example.

Is there any on-chain evidence of a lighting channel (before or after channel closure) or is that something that is discarded before settling on-chain?

Thanks in advance

Update: I found the 2-of-2 multisig tag on the input of a commitment transaction but there is no similar tag on the funding transaction (the one that creates the multi-sig output). The commitment transaction (the one that spends the mult-sig output) shows the following (op_code inputs omitted)

OP_PUSHNUM_2
OP_PUSHBYTES_33
OP_PUSHBYTES_33
OP_PUSHNUM_2
OP_CHECKMULTISIG

There is also an nSequence=0xffffffff and a prev output script of

OP_0
OP_PUSHBYTES_32

But I don't see things mentioned in the whitepaper like: OP_IF/ELSE/ENDIF, SIGHASH_NOINPUT, or HTLC

again i am just learning and I only want to know where the interesting bits are as I continue reading.

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  • The lightning-rfc is a better source than the whitepaper. It would also help if you could provide transactions in hex or pointers to them in some blockexplorer otherwise it is hard to help. You could also check the issue tracker for some implementations where discussions of channel points (transactions) took place for debugging e.g: github.com/ElementsProject/lightning/issues/1738 Commented Jun 23, 2021 at 19:16

1 Answer 1

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Transactions that create funding outputs have no special characteristics. The funding output is merely some type of segwit-output that can facilitate 2-of-2, i.e. P2SH-P2WSH or P2WSH, with P2TR to become available soon as well.

A transaction in which the channel owners collaborate to close a channel amicably does not have special characteristics except that it has a 2-of-2 input. If a channel gets closed by one channel owner unilaterally, it will use a commitment transaction with the characteristic timelocks on the closing party’s outputs, as well as optionally some anchor outputs or HTLC outputs.

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