<p>PPCoin and other coins use Proof of Stake in addition to Proof of Work.  Stake is how long a coin has been idle multiplied by its value.  If you've been holding many coins for a long time, you can spend their coin age in lieu of poof of work.  The fear is that someone will hoard coins, gather a bunch of age, and then double-spend and use his accrued coin age to give each spend 6 confirmations immediately, without needing CPU work.</p>

<p>It's a valid concern, in my opinion.</p>

CC BY-SA 3.0
2013-04-09T05:59:14.647Z
2013-04-09T05:59:14.647Z
Eyal
<p>Can anyone explain the vulnerability of PPCoin and possibly other Proof of Stake coins that might allow an attacker to double spend? I've seen one explanation here: </p>

<p><a href="https://bitcointalk.org/index.php?topic=169204.msg1761154#msg1761154" rel="nofollow">https://bitcointalk.org/index.php?topic=169204.msg1761154#msg1761154</a></p>

<p>but it wasn't clear. </p>

<peercoin>
Can anyone explain this vulnerability in PPC
q99ujacw
# Can anyone explain this vulnerability in PPC

(Asked by: username_0 on 2013-04-08)

Can anyone explain the vulnerability of PPCoin and possibly other Proof of Stake coins that might allow an attacker to double spend? I've seen one explanation here:

<https://bitcointalk.org/index.php?topic=169204.msg1761154#msg1761154>

but it wasn't clear.

**Tags:** peercoin


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## 1 answers

### Answer by username_1 on 2013-04-09. Score: 3 | Accepted answer

PPCoin and other coins use Proof of Stake in addition to Proof of Work. Stake is how long a coin has been idle multiplied by its value. If you've been holding many coins for a long time, you can spend their coin age in lieu of poof of work. The fear is that someone will hoard coins, gather a bunch of age, and then double-spend and use his accrued coin age to give each spend 6 confirmations immediately, without needing CPU work.

It's a valid concern, in my opinion.


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