Thank you for contacting Cryptopia Support.
As AU has fallen victim to a 51% attack we have determined that the coin no longer meets our standard listing requirements and has been delisted.
All holders of AU were emailed notifying them that withdrawals would be enabled from 02:00:00 AM (UTC) on the 20th of December 2018.
As our users have now withdrawn 100% of the coins remaining in our AU wallet, there would be no advantage to providing further notice of this coin's delisting as withdrawals of AU would not be possible during the notice period.
I am sorry that you were not able to withdraw your coins in time, however there is nothing further we can do to recover these funds.
Kind regards,
Olivia
???Cryptopia Support
![Huh](https://bitcointalk.org/Smileys/default/huh.gif)
"""I am sorry that you were not able to withdraw your coins in time"""
![Huh](https://bitcointalk.org/Smileys/default/huh.gif)
? What kind of answer is this? Give me back my money . You allegedly gave 20 hours to withdraw coins? why not 5 hours. Hey citizens and who managed to see the mail? I think it's time to respond to cryptopies. Either customers will prefer decentralization exchanges ...
I sympathize with your plight.
A 51% attack is a blockchain based attack.
https://www.investopedia.com/terms/1/51-attack.aspThere is nothing an exchange can do to prevent it other than delist and remove a coin subject to such an attack if the coin devs are unable to secure the chain against future attacks.
The Aurum coin devs have flat out refused to take responsibility for the attack that occurred on their blockchain.
51% attack explained:
https://support.cryptopia.co.nz/csm?id=kb_article&sys_id=91fc54cddbfc2b0052d2ef728a961948Cryptopia is a peer to peer exchange which means it facilitates the trades between buyer and seller. Cryptopia does not own the coins that are for sale on their site and they are reliant on the blockchain developers to secure their coin networks. Coin balances belong to the buyers and seller on the exchange.
Your Coin Balances are operated by us, and represent entries in your name on the general ledger of ownership of Coins maintained and held by us. This means the Coins in your deposit wallets may be pooled in our internal accounts with other Users' Coins at any time.
Each User's entry in the general ledger of ownership of Coins is held by us, on trust, for that User.
https://www.cryptopia.co.nz/Home/Terms#5Failure by the blockchain developers to secure the blockchain have resulted in the blockchain being attacked.
Blockchain is based on consensus - potentially affected users or the coin developers could fork Aurumcoin to recover, re-establish or re-emburse coins missing from the blockchain balance.
This is something that the Aurum coin developers have not chosen to do. Unlike other coin developers that have re-embursed after 51% attacks on their blockchain and taken responsibility for events that occur on their blockchain.
Cryptopia was entitled to receive the balances, the balances were confirmed by the blockchain nodes but attackers were able to exploit the coin blockchain to reverse the crediting of those balances and thereby stealing the coins from the blockchain held balances.
Cryptopias wallet were kept secure and the private keys were never exposed. This is not something that Cryptopia is responsible for or could control. This has occurred because the blockchain was insecure with insufficient hashrate to secure against such an attack or code to prevent such an attack. (Check pointing code like used by bitcoin and litecoin in the early days when the hashrate was still relatively low can prevent 51% attacks)
https://bitcoin.stackexchange.com/questions/3114/which-blocks-get-to-be-checkpointshttps://bitcoin.stackexchange.com/questions/1797/what-are-checkpointsThe volume of Aurumcoin on coinmarketcap in my opinion is likely to be fake volume aimed to trick potential buyers. Those coins may not even exist - is potential fake bot volume or volume generated by the same buyer and seller to give the impression that the coin is not dead. From 29/10/18 till 23/12/18 the blockchain did not move.
https://www.coinexchange.io/news/post/64/![](https://ip.bitcointalk.org/?u=https%3A%2F%2Fi.imgur.com%2FTpnHppE.png&t=665&c=_2yRxu5E7KV-mQ)
The Aurumcoin wallet has been in maintenance for months and the blockchain hasn't moved for 2 months. So the trading that occurred on Coinexchange.io during that time was soley with the exchange ledger balance and most likely fake.