Intersango exchange (formerly Britcoin) - page 9.

phantomcircuit

sr. member

Activity: 463

Merit: 252

Quote from: dooglus on July 20, 2011, 01:08:28 PM

If I can sell 0.00000000 BTC for 0.00000001 GBP, I could do that 100 million times and make a whole British Pound! I wonder how you get around the limits.

The code is doing:

Code:

order_worthwhile_check($amount, $amount_disp, '0.0005');
order_worthwhile_check($want_amount, $want_amount_disp, '0.0005');

That check is for the order as a whole, not for the partial orders produced when a trade occurs.

So if you place an order 1 BTC for 10 GBP and it gets filled as 0.99999999 BTC you will have a remaining partial order of 0.000000001 BTC.

So this isn't something that's exploitable, basically peoples orders are getting rounded up or down by very small amounts of 0.00000001 for the entire order.

So in the worst case someone might have 0.002% of their order rounded off.

dazedtrader

newbie

Activity: 25

Merit: 0

It's just happened again: https://britcoin.co.uk/api/ticker.php

dooglus

legendary

Activity: 2940

Merit: 1333

If I can sell 0.00000000 BTC for 0.00000001 GBP, I could do that 100 million times and make a whole British Pound! I wonder how you get around the limits.

The code is doing:

Code:

order_worthwhile_check($amount, $amount_disp, '0.0005');
order_worthwhile_check($want_amount, $want_amount_disp, '0.0005');

dooglus

legendary

Activity: 2940

Merit: 1333

Quote from: dazedtrader on July 20, 2011, 12:27:04 PM

The zero trades I saw were on Britcoin, by the way.

Curiouser and curiouser.

dazedtrader

newbie

Activity: 25

Merit: 0

The zero trades I saw were on Britcoin, by the way.

phantomcircuit

sr. member

Activity: 463

Merit: 252

Quote from: dooglus on July 19, 2011, 08:50:43 PM

Quote from: phantomcircuit on July 19, 2011, 08:11:24 PM

The limits on britcoin are artificial. The actual precisions is 8 places after the decimal, or 0.00000001.

Of course, but since britcoin is using the intersango code I'd have thought the same artificial limits would be in place for the USD exchange too. The artificial limits were put in place for a reason (it helps prevent these zero trades and code errors, for one thing), so it seems odd that they're not on all the intersango exchanges.

What I posted where trades, probably the tail end of orders for normal amounts.

dooglus

legendary

Activity: 2940

Merit: 1333

Quote from: phantomcircuit on July 19, 2011, 08:11:24 PM

The limits on britcoin are artificial. The actual precisions is 8 places after the decimal, or 0.00000001.

Of course, but since britcoin is using the intersango code I'd have thought the same artificial limits would be in place for the USD exchange too. The artificial limits were put in place for a reason (it helps prevent these zero trades and code errors, for one thing), so it seems odd that they're not on all the intersango exchanges.

phantomcircuit

sr. member

Activity: 463

Merit: 252

Quote from: dooglus on July 19, 2011, 05:52:43 PM

What happened to the limits of 0.005 or so? On britcoin there's a minimum size for both BTC and GBP, and it's something of that order.

Isn't this USD exchange using the same code?

The limits on britcoin are artificial. The actual precisions is 8 places after the decimal, or 0.00000001.

dooglus

legendary

Activity: 2940

Merit: 1333

What happened to the limits of 0.005 or so? On britcoin there's a minimum size for both BTC and GBP, and it's something of that order.

Isn't this USD exchange using the same code?

phantomcircuit

sr. member

Activity: 463

Merit: 252

Quote from: dazedtrader on July 19, 2011, 02:58:14 PM

It looks like a trade of amount 0 has gone through and has caused the problem. This is the culprit:

Code:

{"date": 1311104701, "price": , "amount": 0}

I also noticed a trade in the order book earlier today where one of the quantities was zero so looks like the validation may need tightening up somewhere. (Edit: that's a guess, I haven't read the code in any detail)

That's a good guess.

The issue is that 2 trades went through in which one side got 0.

| 16947 | 18518 | 1 | 18539 | 0 | 2011-07-19 18:44:01 |
| 16973 | 18548 | 2 | 18562 | 0 | 2011-07-19 20:45:01 |

Those numbers are scaled 10^8, so those are trades for 0.00000001 for 0 and 0.00000002 for 0.

dazedtrader

newbie

Activity: 25

Merit: 0

It looks like a trade of amount 0 has gone through and has caused the problem. This is the culprit:

Code:

{"date": 1311104701, "price": , "amount": 0}

I also noticed a trade in the order book earlier today where one of the quantities was zero so looks like the validation may need tightening up somewhere. (Edit: that's a guess, I haven't read the code in any detail)

dazedtrader

newbie

Activity: 25

Merit: 0

Just a heads up - the ticker API seems to be broken as it is returning:

Code:

{"ticker": {"vol": 561.62370667, "buy": 8.4035, "sell": 8.65,
Warning: Division by zero in /var/www/britcoin.co.uk/htdocs/api/ticker.php on line 72
"last": }}

phantomcircuit

sr. member

Activity: 463

Merit: 252

Quote from: dooglus on July 18, 2011, 09:54:26 PM

Is it 0% commission? If so, that may be worth mentioning, since the competition isn't.

It is.

spruce

full member

Activity: 140

Merit: 100

There are now 4 BTC offers at Intersango.us. It's gradually creeping up in volume, although the USD/BTC rates in those 4 offers aren't the best place to buy BTC right now!

dooglus

legendary

Activity: 2940

Merit: 1333

Is it 0% commission? If so, that may be worth mentioning, since the competition isn't.

spruce

full member

Activity: 140

Merit: 100

Quote from: Donald_Norman on July 18, 2011, 06:39:18 PM

The USD platform

Intersango.us

just came online a tiny bit ago but we have had a difficult time making people aware of it's existence. It uses dwolla as a payment method as well as bank transfers. When I leave the US I will open a better EUR account. If have enjoyed using Britcoin please tell your US friends about Intersango.us. Right now we do not even have any Bitcoins listed in the orderbook

I just listed a bitcoin there. I even put a (temporary) free plug for you in my signature.

Donald_Norman

member

Activity: 100

Merit: 10

The USD platform

Intersango.us

just came online a tiny bit ago but we have had a difficult time making people aware of it's existence. It uses dwolla as a payment method as well as bank transfers. When I leave the US I will open a better EUR account. If have enjoyed using Britcoin please tell your US friends about Intersango.us. Right now we do not even have any Bitcoins listed in the orderbook

Donald_Norman

member

Activity: 100

Merit: 10

Hi guys,

I understand the banking for EUR might not be ideal. However since some of us are living in Poland it was the option we came to. We will be opening a better account. Since the service is free though it is actually very advantageous right now.

defxor

hero member

Activity: 530

Merit: 500

Quote from: sonba on July 07, 2011, 02:03:42 AM

yes, SEPA costs cannot be more than the one for local within-country transfers (if same currency!). Hence, most of EURO banks (read: banks in countries which do have the EURO as their official currency) do not charge anything at all for wiring.

Not only countries with euro. The banks I know of in Sweden (still using SEK) also do free SEPA transfers.

spruce

full member

Activity: 140

Merit: 100

Quote from: BitMofo on July 16, 2011, 03:21:30 PM

Quote from: spruce on July 16, 2011, 03:19:23 PM

Quote from: BitMofo on July 16, 2011, 03:17:40 PM

Ok so it shows up in blockexplorer (http://blockexplorer.com/address/1GDGhnQFFzCQ2CvtKr4pDRW4J5Wo3yk9Xp)
How long until I see it in my account?
Thanks for the help spruce!

Is the block count in your wallet up to date? Mine shows 136606.

Nope my counts on 136455 and growing. So this must be because the client wasn't run for a while then? It still needs to check all of the blocks that have been created?

It needs to get up to the block which includes the transaction you are interested in, then it will show in your wallet. Yes, if not run it gets behind.

Topic: Intersango exchange (formerly Britcoin) - page 9. (Read 75372 times)