<p>There's 2 versions of ASICBOOST:</p>

<ul>
<li>Overt where miners use bits in the version number as extra nonce space</li>
<li>Covert where miners "mine" merkle trees with 4 bytes collisions</li>
</ul>

<p>The overt version is very easily detectable, whereas the covert one isn't. </p>

<p>To mine these merkle trees for the overt version, miners need to shuffle the transactions in the block. </p>

<p>Without Segwit transactions in a block, it is possible to do it in a very low number of SHA-256 operations ; with Segwit transactions, a change of order forces miners to recompute the witness commitment which is stored in the coinbase. That makes it way more expensive to mine merkle trees and destroys the advantage covert ASICBOOST provides.</p>

<p>You can find a detailed explanation <a href="https://bitslog.wordpress.com/2017/04/10/the-relation-between-segwit-and-asicboost-covert-and-overt/" rel="noreferrer">here</a>.</p>

CC BY-SA 4.0
2018-06-13T19:18:53.283Z
SegWit doesn’t eliminate the ability to achieve the full performance of _covert_ ASICBOOST. Study more carefully the source you cited. If the block has only 1 or 2 transactions, then the difference in _covert_ ASICBOOST performance is not very significant. Given Lightning Networks, we can expect the possibility of settlement transactions that can occupy an entire block. So then even blocks with only 1 or 2 transactions will not be conspicuous evidence of _covert_ ASICBOOST. Let’s presume LN Mt.Box hubs can possibly collude with _covert_ ASICBOOST miners.
Shelby Moore III
CC BY-SA 4.0
2018-06-14T10:06:56.530Z
It is true that the less transactions, the overhead is lessened. However, Lightning settlement transactions don't take more space than other transactions. The coooperative case is a simple 2-of-2 multisig spend, and thousands of those happen per day already.
alcio
CC BY-SA 4.0
2018-06-15T23:46:23.893Z
Bitcoin will become a settlement network between whales with huge transactions with a plurality of inputs and/or outputs. Think of centralized exchanges which is what LN Mt. Box hubs will become. The on-chain transaction fees with be $50,000. Only the uber wealthy will transact on-chain and open LN channels on-chain. Everyone else will be on fractional reserve banking. That is [the master plan and the only way the technology works](https://bitcointalk.org/index.php?action=profile;u=2189580;sa=showPosts).
Shelby Moore III
CC BY-SA 3.0
2017-07-11T13:59:03.720Z
2017-07-11T13:59:03.720Z
alcio
<p>I know that ASIC BOOST exploits the fact that the blockheaders are not a multiple of 64 bytes, but what is the change in Segwit that prevents this? Are they always a multiple of 64 bytes now for example?</p>

<asic><segregated-witness><block-header><asic-resistance><asicboost>
How does Segwit prevent ASICBOOST?
Maestro
# How does Segwit prevent ASICBOOST?

(Asked by: username_0 on 2017-07-11)

I know that ASIC BOOST exploits the fact that the blockheaders are not a multiple of 64 bytes, but what is the change in Segwit that prevents this? Are they always a multiple of 64 bytes now for example?

**Tags:** asic, segregated-witness, block-header, asic-resistance, asicboost


---

## 1 answers

### Answer by username_1 on 2017-07-11. Score: 9 | Accepted answer

There's 2 versions of ASICBOOST:

* Overt where miners use bits in the version number as extra nonce space
* Covert where miners "mine" merkle trees with 4 bytes collisions

The overt version is very easily detectable, whereas the covert one isn't.

To mine these merkle trees for the overt version, miners need to shuffle the transactions in the block.

Without Segwit transactions in a block, it is possible to do it in a very low number of SHA-256 operations ; with Segwit transactions, a change of order forces miners to recompute the witness commitment which is stored in the coinbase. That makes it way more expensive to mine merkle trees and destroys the advantage covert ASICBOOST provides.

You can find a detailed explanation [here](https://bitslog.wordpress.com/2017/04/10/the-relation-between-segwit-and-asicboost-covert-and-overt/).

> **Comments:**
> **username_2**: SegWit doesn’t eliminate the ability to achieve the full performance of _covert_ ASICBOOST. Study more carefully the source you cited. If the block has only 1 or 2 transactions, then the difference in _covert_ ASICBOOST performance is not very significant. Given Lightning Networks, we can expect the possibility of settlement transactions that can occupy an entire block. So then even blocks with only 1 or 2 transactions will not be conspicuous evidence of _covert_ ASICBOOST. Let’s presume LN Mt.Box hubs can possibly collude with _covert_ ASICBOOST miners.  
> **username_1**: It is true that the less transactions, the overhead is lessened. However, Lightning settlement transactions don't take more space than other transactions. The coooperative case is a simple 2-of-2 multisig spend, and thousands of those happen per day already.  
> **username_2**: Bitcoin will become a settlement network between whales with huge transactions with a plurality of inputs and/or outputs. Think of centralized exchanges which is what LN Mt. Box hubs will become. The on-chain transaction fees with be $50,000. Only the uber wealthy will transact on-chain and open LN channels on-chain. Everyone else will be on fractional reserve banking. That is [the master plan and the only way the technology works](https://bitcointalk.org/index.php?action=profile;u=2189580;sa=showPosts).  

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