user5406: This answer to How is a node in the middle prohibited from keeping the money in a routed Payment in Lightning network? describes how a Hashed Timelock Contract would be used to exchange the "secret" for a payment. This sounds a lot like the Zero-Knowledge Contingent Payment described by Greg Maxwell.
Would I be correct in assuming that the HTLC would be implemented including a ZKCP?

user2306: Not really. Both use OP_CLTV, in order to recover from a situation where one side refuses to participate in the protocol, but other than that, they're pretty different.
ZKCP has a zero knowledge proof communicated outside of the blockchain. On the other hand, HTLC passes signed transactions back and forth to update a channel.

5406: <p>This answer to <a href="https://bitcoin.stackexchange.com/a/43190/5406">How is a node in the middle prohibited from keeping the money in a routed Payment in Lightning network?</a> describes how a Hashed Timelock Contract would be used to exchange the "secret" for a payment. This sounds a lot like the <a href="https://bitcointalk.org/index.php?topic=1378318.0" rel="nofollow noreferrer">Zero-Knowledge Contingent Payment</a> described by Greg Maxwell.</p>

<p>Would I be correct in assuming that the HTLC would be implemented including a ZKCP?</p>
 2306: <p>Not really. Both use OP_CLTV, in order to recover from a situation where one side refuses to participate in the protocol, but other than that, they're pretty different.</p>

<p><a href="https://bitcoincore.org/en/2016/02/26/zero-knowledge-contingent-payments-announcement/" rel="nofollow">ZKCP</a> has a zero knowledge proof communicated outside of the blockchain. On the other hand, HTLC passes signed transactions back and forth to update a channel.</p>
