<p>It was in the context of the peer sending an invalid point. The proposed scheme would not detect that immediately, and so would do extra (wasted) work. </p>

<p>However the peer could equally waste your time by sending a valid point (possibly without knowing the private key) and just abandoning the protocol after you've done the work anyway.</p>

CC BY-SA 4.0
2020-04-09T06:32:32.337Z
2020-04-09T10:40:23.827Z
2020-04-09T10:40:23.827Z
Peter Dettman
<p>Peter Dettman notes that <a href="https://github.com/bitcoin-core/secp256k1/pull/363" rel="nofollow noreferrer">ECDH peers can waste each other's time at will</a>. What does he mean? Can this be weaponized against Lightning nodes?</p>

CC BY-SA 4.0
2020-03-18T18:15:58.357Z
Could it be that he is referring to [not being able to use Montgomery ladders](https://crypto.stackexchange.com/a/68286/12089)?
Janus Troelsen
<lightning-network><cryptography><ecdh>
Can ECDH peers waste each other's time at will?
Janus Troelsen
# Can ECDH peers waste each other's time at will?

(Asked by: username_0 on 2019-09-19)

username_1 username_1 notes that [ECDH peers can waste each other's time at will](https://github.com/bitcoin-core/secp256k1/pull/363). What does he mean? Can this be weaponized against Lightning nodes?

**Tags:** lightning-network, cryptography, ecdh

> **Comments:**
> **username_0**: Could it be that he is referring to [not being able to use Montgomery ladders](https://crypto.stackexchange.com/a/68286/12089)?  

---

## 1 answers

### Answer by username_1 on 2020-04-09. Score: 2 | Accepted answer

It was in the context of the peer sending an invalid point. The proposed scheme would not detect that immediately, and so would do extra (wasted) work.

However the peer could equally waste your time by sending a valid point (possibly without knowing the private key) and just abandoning the protocol after you've done the work anyway.


---

