<p>Contrary to popular belief, Bitcoin does not use the longest chain. This is because of exactly the scenario in your question. Instead Bitcoin uses the chain with the most cumulative work. This is calculated by summing the difficulty of each block in the blockchain. If you made a blockchain that has more blocks than the current main chain but has blocks at a lower difficulty, then your chain won't be accepted because it has less work than the main chain.</p>

<p>You would have to have a chain that is so long that you have done more work, or have blocks with a higher difficulty so you have done more work. Either way, more work is required and that is prohibitively expensive.</p>

CC BY-SA 4.0
2020-05-21T07:31:55.483Z
Thank you very much for your reply. But doesn't mean it's still possible? Especially easy for new cryptos that have very little cumulative work computed? Thanks again.
good_evening
CC BY-SA 4.0
2020-05-21T16:54:14.680Z
Yes it is possible to do that on new coins with little cumulative work. IIRC this has been done before on such coins.
Ava Chow
CC BY-SA 4.0
2020-05-20T21:24:39.217Z
2020-05-20T21:24:39.217Z
Ava Chow
<p>Let's say I create the longest Blockchain for Bitcoin ever (let's assume it's possible). And then I add 50,000 nodes to the Bitcoin network and I use the aforementioned chain, wouldn't I be able to deceive everyone? Bitcoin trusts the longest chain, so if I have the longest chain and own majority of the nodes, wouldn't I be able to convince others some account has any amount of Bitcoins I desire? </p>

<p>If it's not possible for Bitcoin for some reason, is it possible to do the same for a cryptocurrency that was created recently?</p>

<p>Sorry for the stupid question, and thank you very much.</p>

<security>
What prevents me to create the longest chain and multiple nodes, and deceiving everyone?
good_evening
# What prevents me to create the longest chain and multiple nodes, and deceiving everyone?

(Asked by: username_0 on 2020-05-20)

Let's say I create the longest Blockchain for Bitcoin ever (let's assume it's possible). And then I add 50,000 nodes to the Bitcoin network and I use the aforementioned chain, wouldn't I be able to deceive everyone? Bitcoin trusts the longest chain, so if I have the longest chain and own majority of the nodes, wouldn't I be able to convince others some account has any amount of Bitcoins I desire?

If it's not possible for Bitcoin for some reason, is it possible to do the same for a cryptocurrency that was created recently?

Sorry for the stupid question, and thank you very much.

**Tags:** security


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## 1 answers

### Answer by username_1 on 2020-05-20. Score: 2 | Accepted answer

Contrary to popular belief, Bitcoin does not use the longest chain. This is because of exactly the scenario in your question. Instead Bitcoin uses the chain with the most cumulative work. This is calculated by summing the difficulty of each block in the blockchain. If you made a blockchain that has more blocks than the current main chain but has blocks at a lower difficulty, then your chain won't be accepted because it has less work than the main chain.

You would have to have a chain that is so long that you have done more work, or have blocks with a higher difficulty so you have done more work. Either way, more work is required and that is prohibitively expensive.

> **Comments:**
> **username_0**: Thank you very much for your reply. But doesn't mean it's still possible? Especially easy for new cryptos that have very little cumulative work computed? Thanks again.  
> **username_1**: Yes it is possible to do that on new coins with little cumulative work. IIRC this has been done before on such coins.  

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