<p>One example of this are the <a href="https://bitcointalk.org/index.php?topic=293382.0" rel="nofollow noreferrer">hash collision bounties</a>. There are bitcoins out there that can be unlocked by submitting an example of a hash collision for SHA1 (claimed in 2017), SHA256, RIPEMD160, RIPEMD160(SHA256()) and SHA256(SHA256()).</p>
<p>As the bitcointalk post above mentions, since the scriptSigs unlocking these bounties don't cryptographically sign the transaction outputs, anyone can copy them into a transaction that would send the coins to them. This applies to all bitcoin &quot;bounties&quot; or &quot;puzzles&quot;.</p>
<p>The posts suggests you mine the block containing this transaction yourself, but unless you have a lot of mining hardware you won't be able to do that. Even then, you wouldn't be safe against a chain reorganization by a large miner or mining pool if the bounty were big enough. Simply broadcasting the transaction carries a high risk of a miner replacing your transaction with theirs or someone intercepting your transaction and broadcasting their version to miners faster and/or with a higher fee.</p>

CC BY-SA 4.0
2022-03-09T05:33:39.480Z
So if the solver does not have a large computing power, he/she always carries the risk of not receiving the bounty? Is there a way to remedy this problem other than by upgrading mining hardware?
Miyamoto Musashi
CC BY-SA 4.0
2022-03-09T11:28:26.547Z
Yes, receiving a reward for publicly submitting information that can be copied by anyone else to also try to claim the reward can never be safe. The Bitcoin network will reach consensus on which of those transactions was first, but it cannot know which of them was *actually* first.
Vojtěch Strnad
CC BY-SA 4.0
2022-03-08T18:37:07.837Z
2022-03-08T18:37:07.837Z
Vojtěch Strnad
<p>if suppose a someone offers a prize for anyone that can solve a specific challenge, how will the solver make sure that he/she collects the reward? Does the solver need to send the solution directly to this anonymous person?</p>

<hash><signature>
Bitcoin transaction inquiry
Miyamoto Musashi
# Bitcoin transaction inquiry

(Asked by: username_0 on 2022-03-08)

if suppose a someone offers a prize for anyone that can solve a specific challenge, how will the solver make sure that he/she collects the reward? Does the solver need to send the solution directly to this anonymous person?

**Tags:** hash, signature


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## 1 answers

### Answer by username_1 on 2022-03-08. Score: 2

One example of this are the [hash collision bounties](https://bitcointalk.org/index.php?topic=293382.0). There are bitcoins out there that can be unlocked by submitting an example of a hash collision for SHA1 (claimed in 2017), SHA256, RIPEMD160, RIPEMD160(SHA256()) and SHA256(SHA256()).

As the bitcointalk post above mentions, since the scriptSigs unlocking these bounties don't cryptographically sign the transaction outputs, anyone can copy them into a transaction that would send the coins to them. This applies to all bitcoin "bounties" or "puzzles".

The posts suggests you mine the block containing this transaction yourself, but unless you have a lot of mining hardware you won't be able to do that. Even then, you wouldn't be safe against a chain reorganization by a large miner or mining pool if the bounty were big enough. Simply broadcasting the transaction carries a high risk of a miner replacing your transaction with theirs or someone intercepting your transaction and broadcasting their version to miners faster and/or with a higher fee.

> **Comments:**
> **username_0**: So if the solver does not have a large computing power, he/she always carries the risk of not receiving the bounty? Is there a way to remedy this problem other than by upgrading mining hardware?  
> **username_1**: Yes, receiving a reward for publicly submitting information that can be copied by anyone else to also try to claim the reward can never be safe. The Bitcoin network will reach consensus on which of those transactions was first, but it cannot know which of them was *actually* first.  

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