Tl;dr: This post is about the 56 years ahead and unconfirmed c4208b651147cb999fff… transaction which is constantly flooding the Peercoin network and which can be seen in the live transactions of the mempool. If you are not aware of this transaction, you don’t need to read further.
[i]A few days ago a user had an issue with his wallet that wasn’t processing a transaction. He was using an old version of Peerunity which had an old copy of the block chain (as it was certainly downloaded with an old version of ppcoin’s protocol < 0.4). He was using Windows XP, which also had an issue with the time.
He noticed the issue when he realized that his transaction d4d243e4f9f598053d2e8aa4e211b5155d9b5cadbb17a2fd4d7bdbe95868a4c8 wasn’t accepted by any new minted/mined blocks of the blockchain and thus couldn’t be confirmed. Also, he noticed that it kept popping up in the live transaction feed (mempool) of the blockchain while he had his Peerunity wallet open. What was happening is that his Peerunity wallet kept broadcasting the “broken” transaction on the network.
He thus decided to downloaded the latest Peerunity version, but since he had a pre-downloaded and certainly a broken version of the blockchain on his computer, his new Peerunity client version kept displaying the following error message: “Warning: Invalid checkpoint found! You may need to upgrade or notify the developer”.
The solution was simple. First he had to adjust his computer’s time. Then he just had to backup his wallet (wallet.dat file) and delete his version of the blockchain which was contained in his “C:\Program Files (x86)\PPCoin” folder (blk0001.dat and blkindex.dat files). After the next launch of Peerunity, he had to wait for the blockchain to be fully downloaded and after that, his transaction went through and was accepted and confirmed by the network.[/i]
All this to say that the unconfirmed 56 years ahead c4208b651147cb999fff… transaction that we see popping up in mempool will never be confirmed and is belonging to someone who is running an old version of the protocol or has an outdated copy of the blockchain that cannot be used with his wallet client. The fact that this person was able to move the funds already is certainly because (s)he successfully proceeded with the transaction later with another wallet from another computer after (s)he realized that there was an issue. The faulty instance is still running and I suspect this is someone who’s supporting the network with a full active node.
In short, the unconfirmed c4208b651147cb999fff… transaction is not a double spending attack as it was stated in this topic nor an issue with the blockchain or with bkchain.org. This is simply someone who has an old version of Peercoin and left an outdated instance running and trying to broadcast this “broken” transaction (could be with Peerunity). This person should remove his/her old copy of the blockchain and upgrade his/her client. This also doesn’t constitute a security risk for Peercoin’s network, nor for this person’s funds.
Edit: It is to be noted that this “display” issue is only relative to bkchain.org. The latest development version of ppcoind doesn’t display this transaction in mempool, proof:
$ ppcoind getrawmempool
ppcoind getrawmempool
[
"5623583d8570629861c738dfcce317c1dbddc04186d5d8fbc5ca3ae86306a9de",
"893522ccd883419733c7286073082305872a806a827a06c812a715d6c74efb1c"
]
Edit: Fixed by the bkchain’s administrator: https://www.reddit.com/r/peercoin/comments/2ropnn/about_the_mysterious/cnjj2ct
Also posted on reddit: https://www.reddit.com/r/peercoin/comments/2ropnn/about_the_mysterious/