<p>Apparently there is a time until which A can question the transaction because he will have proof for the later transaction that has happened. And B will lose all the money in the channel for broadcasting a previous transaction.</p>

CC BY-SA 3.0
2018-02-08T18:49:01.517Z
If B already send all money to A, wouldn't B not lost anything by trying so, camping on the possibility that A could be offline on that period of time? (btw, how long is the period? It probably is not too long, because the BTC is probably locked in the period)
Helin Wang
CC BY-SA 3.0
2018-02-08T18:45:29.483Z
2018-02-08T18:45:29.483Z
hvaminion
<p>I understand that after a channel is created, A and B need to agree and sign to create a new transaction. The new transaction overrides the previous transaction. A or B could quit the channel by broadcasting the transaction onto Bitcoin network so that the transaction is final:</p>

<pre><code>txn 0: A:0.5, B:0.5
txn 1: A:0.3, B:0.7
txn 2: A:0.9, B:0.1
</code></pre>

<p>A or B quit channel, broadcast <code>txn 2</code>, so A will have 0.9 and B will have 0.1</p>

<p>But what if B quit the channel, broadcasting <code>txn 1</code> rather than <code>txn 2</code> on to the Bitcoin network? Wouldn't the <code>txn 1</code> becomes final and B could walk away with 0.7?</p>

CC BY-SA 3.0
2018-02-11T04:31:25.613Z
Welcome to Bitcoin.SE! I can see you have some experience on SE sites so I will leave you to it.
Willtech
<transactions><bitcoin-core><blockchain><lightning-network>
Lightning Network: what if one broadcast an old transaction?
Helin Wang
# Lightning Network: what if one broadcast an old transaction?

(Asked by: username_0 on 2018-02-08)

I understand that after a channel is created, A and B need to agree and sign to create a new transaction. The new transaction overrides the previous transaction. A or B could quit the channel by broadcasting the transaction onto Bitcoin network so that the transaction is final:

```
txn 0: A:0.5, B:0.5
txn 1: A:0.3, B:0.7
txn 2: A:0.9, B:0.1

```

A or B quit channel, broadcast `txn 2`, so A will have 0.9 and B will have 0.1

But what if B quit the channel, broadcasting `txn 1` rather than `txn 2` on to the Bitcoin network? Wouldn't the `txn 1` becomes final and B could walk away with 0.7?

**Tags:** transactions, bitcoin-core, blockchain, lightning-network

> **Comments:**
> **username_1**: Welcome to Bitcoin.SE! I can see you have some experience on SE sites so I will leave you to it.  

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## 1 answers

### Answer by username_2 on 2018-02-08. Score: 0 | Accepted answer

Apparently there is a time until which A can question the transaction because he will have proof for the later transaction that has happened. And B will lose all the money in the channel for broadcasting a previous transaction.

> **Comments:**
> **username_0**: If B already send all money to A, wouldn't B not lost anything by trying so, camping on the possibility that A could be offline on that period of time? (btw, how long is the period? It probably is not too long, because the BTC is probably locked in the period)  

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