<blockquote>
  <p>My understanding is that wallets can avoid creating malleable transactions.</p>
</blockquote>

<p>It depends. For typical transactions, <strong>standardness</strong> rules on the network make malleated transactions unlikely to be relayed and confirmed. But this is just based on goodwill of the network and miners. As was shown recently, it's trivial for miners to stop enforcing this. As there are no consensus rules that prevent malleated transactions from confirming, generally <strong>every</strong> transaction is at risk.</p>

<p>Perhaps what you are referring to is that good wallet software can <em>cope</em> with malleability. They detect when a modified version of their transactions gets confirmed, and treat it as a replacement for the original. For simple payments, this is usually sufficient.</p>

<blockquote>
  <p>If so, why does a lightning network need SegWit or some other tx malleability fix?</p>
</blockquote>

<p>Because Lightning does something that regular transactions don't do: rely on having pre-signed transactions depending on unbroadcasted potential future transactions, and expecting them to not be invalidated. Malleability breaks this assumption.</p>

CC BY-SA 3.0
2017-03-12T07:22:28.887Z
2017-03-14T15:39:37.727Z
2017-03-14T15:39:37.727Z
Pieter Wuille
<blockquote>
  <p>My understanding is that wallets can avoid creating malleable transactions</p>
</blockquote>

<p>no. today <strong>any</strong> regular transaction can be malleated, no matter how it was created</p>

CC BY-SA 3.0
2017-03-12T06:45:03.627Z
2017-03-12T06:45:03.627Z
amaclin
<p>My understanding is that wallets can avoid creating malleable transactions. If so, why does a lightning network need SegWit or some other tx malleability fix?</p>

<transaction-malleability>
If well-built wallet software can avoid transaction malleability, why does the lightning network need an additional malleability fix?
murty
# If well-built wallet software can avoid transaction malleability, why does the lightning network need an additional malleability fix?

(Asked by: username_0 on 2017-03-12)

My understanding is that wallets can avoid creating malleable transactions. If so, why does a lightning network need SegWit or some other tx malleability fix?

**Tags:** transaction-malleability


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## 2 answers

### Answer by username_1 on 2017-03-12. Score: 3 | Accepted answer

> My understanding is that wallets can avoid creating malleable transactions.

It depends. For typical transactions, **standardness** rules on the network make malleated transactions unlikely to be relayed and confirmed. But this is just based on goodwill of the network and miners. As was shown recently, it's trivial for miners to stop enforcing this. As there are no consensus rules that prevent malleated transactions from confirming, generally **every** transaction is at risk.

Perhaps what you are referring to is that good wallet software can *cope* with malleability. They detect when a modified version of their transactions gets confirmed, and treat it as a replacement for the original. For simple payments, this is usually sufficient.

> If so, why does a lightning network need SegWit or some other tx malleability fix?

Because Lightning does something that regular transactions don't do: rely on having pre-signed transactions depending on unbroadcasted potential future transactions, and expecting them to not be invalidated. Malleability breaks this assumption.


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### Answer by username_2 on 2017-03-12. Score: 1

> My understanding is that wallets can avoid creating malleable transactions

no. today **any** regular transaction can be malleated, no matter how it was created


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