<p>Absolutely. ECDSA signatures at not unique, they can always be permuted by the signer at will by re-signing with a new nonce. The creator of the block can also choose to reorder or omit transactions to alter the block and then re-sign this to get a new block hash. </p>

CC BY-SA 3.0
2016-12-24T01:29:36.650Z
Does that affect security of blocks/blockchain in PoS systems? Changing a particular block hash, would require recalculating the hashes of blocks on top of it - no?
Albert S
CC BY-SA 3.0
2016-12-27T21:20:13.673Z
This is called "stake grinding" and demolishes the security of PoS systems.
Claris
CC BY-SA 3.0
2015-10-12T07:18:58.970Z
2015-10-12T07:27:27.697Z
2015-10-12T07:27:27.697Z
Claris
<p>In Proof-of-Work, a block hash is costly to manipulate (say, wanting the hash to be even, or have the hash of the hash smaller than some number) since there is a lot of computing power put into selecting the right header to produce a valid hash.</p>

<p>I'm wondering - are the block hashes in the various Proof-of-Stake implementations easier to manipulate since the hashes aren't bound by PoW mining? Could a PoS miner spend some computational time to generate many valid blocks and pick one to use, or are there some other constrains preventing block hash fudging?</p>

<block><hash><proof-of-work><proof-of-stake>
In Proof-of-Stake, can a block creator fudge the block hash?
ThePiachu
# In Proof-of-Stake, can a block creator fudge the block hash?

(Asked by: username_0 on 2015-10-12)

In Proof-of-Work, a block hash is costly to manipulate (say, wanting the hash to be even, or have the hash of the hash smaller than some number) since there is a lot of computing power put into selecting the right header to produce a valid hash.

I'm wondering - are the block hashes in the various Proof-of-Stake implementations easier to manipulate since the hashes aren't bound by PoW mining? Could a PoS miner spend some computational time to generate many valid blocks and pick one to use, or are there some other constrains preventing block hash fudging?

**Tags:** block, hash, proof-of-work, proof-of-stake


---

## 1 answers

### Answer by username_1 on 2015-10-12. Score: 3 | Accepted answer

Absolutely. ECDSA signatures at not unique, they can always be permuted by the signer at will by re-signing with a new nonce. The creator of the block can also choose to reorder or omit transactions to alter the block and then re-sign this to get a new block hash.

> **Comments:**
> **username_2**: Does that affect security of blocks/blockchain in PoS systems? Changing a particular block hash, would require recalculating the hashes of blocks on top of it - no?  
> **username_1**: This is called "stake grinding" and demolishes the security of PoS systems.  

---

