What are replaying attacks on Ethereum?
It looks like the Ethereum classic vs. non-classic confrontation has acquired a new dimension.
Any Ethereum (non-classic) holder willing to take advantage of Ethereum Classic tokens (by selling them or buying anything for them) risks losing a corresponding amount of ETH on the non-classic chain. These are called replaying attacks.
How is it possible? As private keys on both chains are the same, any transaction broadcast on Ethereum Classic can be re-broadcast by a malicious actor on the Ethereum non-classic chain. As a result, when you transfer your ETC to somebody else and you are unlucky, your ETH might move as well.
The simplest worry is that you're going to get replayed in one chain, whenever you do something in the other: any strictly increasing subset of your contract calls can be replayed on the other chain.
You sell the coins, withdraw Bitcoin, and are happy. Until.. you log back in to your client tracking the non-Classic fork and see that your coins are gone. Where did they go? Some ETH-Classic supporter has sent them on to the same address as Poloniex' ETH-Classic deposit address, but this time on the main chain, by simply replaying the transaction in the main chain.
A more comprehensive explanation can be found here:
http://vessenes.com/do-not-mess-with-eth-classic-it-will-f-you-up
UPDATE: Vitalik offers a solution which mitigates replay attacks:
https://blog.ethereum.org/2016/07/26/onward_from_the_hard_fork
This is why steem uses transactions as proof of stake. If steem split then this couldn't happen.
Interesting! Would the same be true for BitShares, or is this a Steem-exclusive innovation? (Steem is based on BitShares, right?)
BitShares also has this feature, though it is optional on BTS. It would be simple enough for BTS users to start using TAPOS after the split.
On Steem it is mandatory.
I just lost thousands in the DAO. They are not issuing us ETC and I bought into ETH at the wrong time, during the DAO crowdfund. I am an idiot, I can barely breath... I know, it is what it is and this too will pass but OMG its scary. I am poor, disabled and going out on a limb from the start. I'm screwed... @dan
Thanks for clearing this up @dantheman !!!
Just when I thought the ETC and ETH drama was settling yesterday with prices somewhat holding stable, I look on Polo and see ETC making a 300% increase. The trollbox there is going nuts! I assume that these replay attacks are the reason for this shift in the market.
I'm still trying to learn more about cryptocurrency, but is the reason ETC made this huge market move have to do with these replay attacks? Sounds like it's safer to keep ETC until this issue is resolved with ETH.
Having said that, how would ETH even fix this issue?
down at 260% right now - but it's almost like watching a vertical ping pong game ;-)
https://coinmarketcap.com/
I don't think so. I think it's unrelated.
EDIT: on second thought, maybe there is some connection between those two: the risk of replay attacks might dwarf the selling pressure for ETC.
Great post, thanks for filling me in. Saving me a LOT of reasearch :) Take a big fat upvote!
Ethereum Classic smells ...
Please do not misuse the word scam.
Doing so is the actual scam.
Thanks for posting this!
Even with the huge percentage gain in eth/classic today the total marketcap for the two coins eth and eth/c are about them same as the ether marketcap was prior to the hard fork and DAO attack ether was trading in the $14.70 range that said it will be interesting to watch in the coming days/ weeks.
I just lost thousands in the DAO. They are not issuing us ETC and I bought into ETH at the wrong time, during the DAO crowdfund. I am an idiot, I can barely breath... I know, it is what it is and this too will pass but OMG its scary. I am poor, disabled and going out on a limb from the start. I feel scammed... @innuendo
i gave you some nice cents do not forget to up vote me please :)
Here is the deal: I'll upvote you only if you produce valuable content. Otherwise Steem will change into a private club.
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