<p>The BIP 34 hash is the block hash at which BIP 34 was fully activated and all blocks less than version 2 were rejected as invalid.</p>

<p><code>nMinimumChainWork</code> is a value that is updated at every release. It is retrieved from the <code>getblockchaininfo</code> RPC of a node that is up at the time of release. <code>nMinimumChainWork</code> is updated at the same time as <code>assumevalid</code>. It is calculated by summing the work done in each block which is calculated by doing <code>2^256/(target+1)</code></p>

CC BY-SA 3.0
2017-10-23T02:38:13.213Z
2017-10-23T02:38:13.213Z
Ava Chow
<p>I'm interested in the technical question of how you got BIP34Hash and nMinimumChainWork.</p>

<p>The changes were introduced here:</p>

<p>nMinimumChainWork: <a href="https://github.com/bitcoin/bitcoin/commit/ad20cddce2097c6561202777fccd257deb1a9810" rel="nofollow noreferrer">https://github.com/bitcoin/bitcoin/commit/ad20cddce2097c6561202777fccd257deb1a9810</a></p>

<p>BIP34Hash and BIP34Height: <a href="https://github.com/bitcoin/bitcoin/commit/33c90cf197223fb95f858db80d090d570d70498a" rel="nofollow noreferrer">https://github.com/bitcoin/bitcoin/commit/33c90cf197223fb95f858db80d090d570d70498a</a></p>

CC BY-SA 3.0
2017-02-13T14:24:14.883Z
You can run the rpc `getblockchaininfo` to get the current chain work. Consequently this is the minimum chain work, as the chain work can never decrease.
user2084795
<bitcoin-core><bitcoind><bitcoin-core-development>
How to get BIP34Hash and nMinimumChainWork?
DATSEC
# How to get BIP34Hash and nMinimumChainWork?

(Asked by: username_0 on 2017-02-02)

I'm interested in the technical question of how you got BIP34Hash and nMinimumChainWork.

The changes were introduced here:

nMinimumChainWork: <https://github.com/bitcoin/bitcoin/commit/ad20cddce2097c6561202777fccd257deb1a9810>

BIP34Hash and BIP34Height: <https://github.com/bitcoin/bitcoin/commit/33c90cf197223fb95f858db80d090d570d70498a>

**Tags:** bitcoin-core, bitcoind, bitcoin-core-development

> **Comments:**
> **username_1**: You can run the rpc `getblockchaininfo` to get the current chain work. Consequently this is the minimum chain work, as the chain work can never decrease.  

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## 1 answers

### Answer by username_2 on 2017-10-23. Score: 3

The BIP 34 hash is the block hash at which BIP 34 was fully activated and all blocks less than version 2 were rejected as invalid.

`nMinimumChainWork` is a value that is updated at every release. It is retrieved from the `getblockchaininfo` RPC of a node that is up at the time of release. `nMinimumChainWork` is updated at the same time as `assumevalid`. It is calculated by summing the work done in each block which is calculated by doing `2^256/(target+1)`


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