But that’s only for user’s convenience if I understand it correctly, right? The crucial data are stored in account tree. Or does the wallet also need the history data to function properly?

Any idea what situations may cause such troubles with syncing that a full blockchain is needed?

LOL, the greediness! https://github.com/BTCGPU/BTCGPU/commit/925606b6cba5e866026fd7726a75470384ed8782

Shouldn’t you change contact e-mail of the domain’s registrant? partners@btc-e.com doesn’t sound very safe…

As far as I know, there isn’t any set of pairs of usable hash functions for each two altcoins. Nonetheless, before you dive in, you need to make sure that the altcoin is tx-malleability-free or that it has BIP65 deployed. If you are interested, I have an optimised script you might use.

Be prepared to run into many hurdles if you’re going to implement this kind of exchange from scratch yourself (I mean, the script is the least issue and you can use an already invented one—but there is much more around it that you need to take care of).

If you replace the getch() function, which is from conio.h, by an equivalent function getchar() from stdio.h, you get the result as stated even in Linux console.

At least I didn't need to #include another header file like the accepted solution.

Hehe, funny task.
It simply prints a space for the digit 3 that will be printed later in main() and also prints the zero that is missing to form output "30". "\r" returns carriage to the beginning of the line so that the digit 3 is printed instead of the space.

Really, just ~0.8 BTC?? That was hardly worth listing. Anyway, if anyone would share how much he lost with this exchange, I'll gladly update the record.

http://hodlwallet.binaryage.com/ is a nice metal wallet, but it's not yet for sale. :c\

Well, some people suggested that it might be good to implement simple wallets for the coins and connect directly to the coin's networks, but it seems to me to be needlessly complicated. So far I prefer to connect to other clients, that provide wallet functionality, via their API. Currently, I already have some support for bitcoind-like API and would like to add support for Electrum and possibly other clients as well.

It should be pretty safe way of trading, although probably not the cheapest and definitely not the fastest (because it's happening on blockchains so one has to wait for confirmations).

Well, a wallet stored on a website is anything, but not safe. It doesn't matter what service it is, whether its operator is fair and honest or a scammer, it just isn't safe. If I may give you advice, get at least Electrum – it's fast, yet you always hold all private keys to your coins.

Edit: aubert's screenshot refers to this event. It's good to read more information about what happened so as one doesn't trust on-line wallet services never again.

Of course, I'm a fan of decentralisation.

Thanks!

Well, if you go to Download, there's a link under "Source Code" leading right to the git repository!

Yes, I try to keep this in mind. Before including an explicit support for an altcoin, I'll have to make sure that it meets certain requirements (like supporting CLTV or non-malleability or possibly something else). Moreover, there also might be altcoins that use different hash functions or generally script encoding which should also be taken into account.

But honestly, I don't expect too many of them to include needed features.

CLTV is one of the things I have in mind when I write about extending the trading part of Coincer. On the other hand, I'm not going to completely abandon current approach. But maybe you know more than I do about current malleability issues in Bitcoin? Because as far as I (think I) know, there shouldn't be anything that could affect this atomic protocol. With BIP66, all parts of BIP62 should be fixed (except those where the malleability comes from ECDSA signatures, but those aren't relevant here as it's the sender who strives for the txid remaining the same and no one else could be affected).

I'll definitely have a look at both Qora and Burst. :c) Although a GUI has a low priority for me, it still is on my ToDo list and eventually will be implemented.

Oh, you just remined me that I haven't finished my summarizing post on this. Anyway, I don't have much time this nor next month, so there won't be probably anything new happening. Then (in March), I'm going to focus on improving P2P layer, communication protocol and probably also refactoring trading, because I need to extend it a little bit, but its current state isn't very nice. You can also expect another testing session. :c)

Thanks!

Just FYI, Coincer (topic) does (in principle) the same thing, but does not tie itself to any particular coin. Instead, it builds its own P2P network to carry out necessary communication between trading parties and building the market. Anyway, good to see alternatives. :c)

You can write down the seed on a piece of paper. This way it has the same quality as a paper wallet in terms of security. Both papers will probably contain instructions on how to redeem the funds so I think I can call it a solution. ;c) The difference is that the seed is "dynamic". You change its balance without touching it. At every moment it contains all your coins.

Or use a hardware wallet (like Trezor) – not only it's safer, but the need for only one paper backup is a really nice thing (the same applies to Electrum). Before Trezor I used to use Electrum on an off-line laptop for signing and had a watch-only wallet on-line (although transfering transactions back and forth via USB was a bit tiring ;c)).

Few weeks ago I compiled a list of cracked cryptocurrency exchanges. Quite huge numbers...