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1  Bitcoin / Development & Technical Discussion / Re: Encrypt/Decrypt arbitrary text using bitcoin keys? on: August 06, 2011, 01:33:16 PM
The encryption algorithm used in bitcoin is ECDSA which does not encrypt text, it's just a signature algorithm.

So, Alice could sign some text with her bitcoin address and Bob would know that it came from her (which would be a rather useful thing to be able to do with transactions).
2  Bitcoin / Development & Technical Discussion / Re: Extending the Alert messages in the protocol on: July 25, 2011, 12:26:13 PM
One way to overcome that problem would be for miners to accept these transactions into blocks for free, simply because they're providing a useful service. However, then smaller exchanges will probably get very "patchy" updates sent out for pricing since only a few pools would be accepting their transactions for free, which kinda sucks Sad
3  Bitcoin / Development & Technical Discussion / Re: Extending the Alert messages in the protocol on: July 25, 2011, 11:45:47 AM
Apologies for the double post.

It occurred to me this morning, would there be transaction fees for these transactions to self? In which case broadcasting the exchange rate could become rather costly!
4  Bitcoin / Development & Technical Discussion / Re: Why not 10 coins per block and a block every 2 minutes? on: July 25, 2011, 12:54:51 AM
I believe blocks are spread in time to ensure that any messages will propagate across the entire network in the duration of a block, 10 minutes being a rather pessimistic view of how long it could take for a message to propagate.

The thing is, faster blocks would take less effort to generate, so to get the same level of security as you currently get by waiting 30 mins for three blocks, you'd have to wait 30 mins for 15 blocks. So, nothing would go faster, you'd just be consuming more traffic spamming the network with more blocks.
5  Bitcoin / Development & Technical Discussion / Re: Extending the Alert messages in the protocol on: July 25, 2011, 12:52:27 AM
That's a good idea, which doesn't require any changes to the protocol, which is always a good thing Cheesy

Of course you do have to trust the exchange, but such is the nature of a centralised exchange Wink
6  Bitcoin / Development & Technical Discussion / Extending the Alert messages in the protocol on: July 25, 2011, 12:03:29 AM
I've recently been in another discussion which led to talking about broadcasting exchange rates through the network (which reduces the load on exchanges).

I know bitcoin has some kind of alert built in but what are the restrictions on it? Specifically, what would need to be changed to allow addressed to broadcast exchange rates and then clients to pick this data up and display it in client? What would be the scalability implications of this?

The biggest problem I can see is that if anyone is allowed to broadcast then people can flood the network. I think this is easily solvable by having nodes only retransmit messages from sources they recognise, and then allowing users to add a set of public keys to verify sources. This way the network as a whole decides which messages are valid to retransmit, simply by if enough peers add the public key as a valid broadcast source.
7  Bitcoin / Wallet software / Re: I need a line of C code on: July 24, 2011, 02:29:23 PM
I wonder if there is some more efficient way of distributing the exchange real-time quote information that doesn't involve polling all of them all the time...

Exchanges could broadcast a message to the network, signed with their private key to ensure authenticity. That way clients which are interested just listen for broadcast messages and display the values contained within, if I remember correctly there is already support within the protocol for broadcasts but only the dev team can send them, so with only a little modification it should be possible to modify it so that anyone can send them.
8  Bitcoin / Bitcoin Discussion / Re: What programming language to learn? on: July 21, 2011, 08:33:12 PM
I have nothing to code just now that I want to code in them, but I hope I shall eventually...

Trying writing a program that aggregates streams of bitcoin financial data using Rx and then selects "interesting" things out of the combinations of these different data streams. That's how I learnt Rx Wink
9  Bitcoin / Bitcoin Discussion / Re: What programming language to learn? on: July 20, 2011, 12:41:30 AM
I learnt haskell in the 48 hours before my exam, which was apparently a very hard exam and I achieved the top classification in Wink

I learnt python in a week when I wanted to build a site for appengine.

I learnt every nook and cranny of java (shudder) in a 12 week group software development coursework project at uni.

The point here is the language that had the most impact was haskell, even though I learnt it the fastest - once I understood the concept the remaining two weeks *after* the exam I spent playing with it taught me very little beyond the precious "aha" moment when I suddenly "got it". The point of 7 languages in 7 weeks is to throw a load of different concepts at you so they all mix together in your head and you're comfortable using the best tool for the job. If you spend several years learning how to use a language and a paradigm you become extremely attached to both of them and start using it for jobs which it isn't ideally suited for.

Obviously once the seven weeks are up you should spend more time learning the languages and paradigms you like in detail, but the important thing is understanding the concepts behind the paradigms (maximising the "aha" moments) not the exact syntax of each language.

What's the use of learning the basics of a load of languages you'll never use any more? Well For example, I no longer use Haskell but still consider it one of my favourite languages because I use LINQ every day, I only love LINQ so much because of what Haskell taught me about the power of that kind of thing. I also develop a lot of networking stuff, and what I learnt from fiddling with erlang for about 12 hours (I never even really wrote a program in it, I just read a lot of the documentation and understood the concept) has a huge influence on that.
10  Bitcoin / Bitcoin Discussion / Re: What programming language to learn? on: July 19, 2011, 11:22:06 PM
I quite like the idea of what 7 languages in 7 weeks tries to do, although I wouldn't have picked those seven languages they're a pretty good selection.

My personal pick for a language a week would be (in order):

  • Python
  • C#
  • Haskell
  • C# (LINQ)
  • Erlang
  • C# (Rx)
  • Lua

Python is a nice simple language to start with, it introduces object orientation, first class methods and a load of the functional things which are increasingly popular these days.

Then you've got C# which is something of the core to this whole thing, mostly for LINQ and Rx which are used as demonstrations of other things (I'll get to that later). Make sure to cover generics since they're pretty vital to both Rx and LINQ (and the entire of C# in general)

Haskell is a beautiful language, it's a bit of a pain to learn if you try and come at it from a "normal programming language, you'll wonder why it can't do the simplest things like loops and assignment. But trust me, once you get the hang of Haskell you'll love it, and it will influence how you program in many other languages.

C# (LINQ), LINQ is Language INtegrated Query in C#, it allows you to do functional style programming with C# objects. It's sort of like using Haskell in C# code with C# objects - it's a nice demonstration of how functional paradigms can fit wonderfully into more classic languages.

Erlang is a wonderful language for concurrency and distributed processing, everything is based around concurrent processes and message passing (which, of course, works rather well over a distributed system exchanging packets (messages).

C# (Rx), Reactive eXtensions is a library for C# which builds upon LINQ to provide filtered message streams... just like concurrent processes passing messages. Once again as with LINQ this is a nice demonstration of how a concept like erlang can be made to work well with more classical languages.

Lua, this is a bit of a curveball. Lua is a weird language, it's pretty much paradigmless, you can do pretty much anything you've done in the previous languages in Lua... but you'll have to write the *paradigm* first. This makes it a great way to understand those little niggling details of the things. Try implementing an enumeration and query framework like LINQ/haskell in Lua and I guarantee you'll learn something Wink

As for *how* to learn these languages, well I'm really not sure what to recommend, perhaps trawl project euler for suitable problems for each paradigm. I usually just pick up a language and start using it when I need it - so although I only *know* 4 or 5 languages really well, I'm confident in having a toolkit of 10 or 20 languages which I can pick up when I need them. Hopefully this 7 languages in 7 weeks thing will give you the same confidence just to pick up a language to use it.
11  Economy / Trading Discussion / Re: What's the Best Trading Exchange for you: Mt Gox, TH, or CampBX? on: July 19, 2011, 04:44:55 PM
Personally I use britcoin when I do occasional trading, simply because it's the easiest to exchange between GBP<->BTC

If I'm interested in the current price, I take a glance at mtgox and tradehill and take an average.

I will *not* use mtgox again for any actual transactions, they've had terrible security since the start and evidently have no idea what they're doing when it comes to security.
12  Economy / Trading Discussion / Re: 100 Pre-Beta Invites - New Secure Multi-Currency Exchange on: July 19, 2011, 04:38:30 PM
Email sent, finally a properly secure bitcoin exchange Cheesy
13  Economy / Economics / Re: What would happen to Bitcoin if the World Echnomy went over to Bitcoins on: July 19, 2011, 01:44:11 PM
What would happen if the Worlds economies all decided to use Bitcoins in place of the USD?

Bitcoin would collapse under the load far before the entire US economy changed over to bitcoin, let alone the entire world economy.

https://en.bitcoin.it/wiki/Scalability

And, assuming we did somehow make bitcoin about 100x more scalable than it is, sometime before the entire US economy transferred over to it we'd have bitcoin heists which made the recent mtgox hack look like pocket change.

Honestly, I have never seen any place anywhere on the Internet where the term "troll" is abused so much. It has become synonymous here with "BTC skeptic", and that is not what it means. It means someone making false comments with the intention to deceive. To disagree with the majority is not trolling. It is discussion.

Skeptic: I'm not convinced BTC is the best new thing.

Troll: Bitcoin is shit. Why are you using it?

Quoted for truth
14  Economy / Economics / Re: When will it be possible to trade on MtGox again? on: June 23, 2011, 02:16:06 PM
What about just circuit breaking withdrawals temporarily?  Allow trading to continue, but keep all money onsite incase a rollback is required.

That's a pretty good idea, so long as it was very well marked on the price graph when the circuit breaker came into operation.

If mt.gox comes back, I'll trust this exchange more then any other.

Why?
15  Economy / Economics / Re: When will it be possible to trade on MtGox again? on: June 21, 2011, 06:10:07 PM
Bitcoin has absurd volatility.

LOTS of time it varied 5% in 30 minutes. There are days with 300% or more variation.

Circuit breakers would only cause people to move to other exchanges.

There are other security measures that can be done, that are not circuit breakers (like requiring confirmation, warning the operator to watch what is happening, etc...)

Nothing could have stopped the selloff except an automated circuit breaker. MagicalTux has to sleep sometime, so operator warnings won't work, confirmation only works if the confirmation is secure, since the accounts were hacked we could assume the confirmation mechanism would have been broken too.

Maybe my numbers were too conservative, cut off the exchange until human intervention in the event of a 50% fall in value in less than half an hour. I think that's quite unlikely, and as far as I can tell from a very quick skim of prices hasn't happened (and gets less likely to happen the bigger the bitcoin economy becomes).
16  Economy / Economics / Re: When will it be possible to trade on MtGox again? on: June 21, 2011, 05:17:50 PM
I dislike circuit breakers.

And unsalted md5 was work of the previous owner, the new owner immediately added salt to md5 (while preparing a new site).


Someone know the exact rules of password to claim account? I am making more and more absurd passwords, 20 character long and using characters that I never used before (And I am not likely to remember) and it still say my password is not secure enough.

Do you also dislike accounts being hacked and a good chunk of the bitcoin economy being sold off in five minutes? Which one do you dislike more, because a circuit breaker that automatically stops trading if the market moves by, e.g. more than 5% in 30 minutes (which has probably never happened except yesterday) would have stopped this whole fandango after just a few thousand dollars worth of coins were sold, instead of millions.

"avoid using the MD5 algorithm in any capacity. As previous research has demonstrated, it should be considered cryptographically broken and unsuitable for further use" [US-CERT]. Salted MD5 is as close to useless as unsalted, using md5 for password hashes on a large banking site handling millions of dollars of other peoples money is incredibly negligent and utterly incompetant.

I had to include Caps, punctuation, a number, and make it almost 20 characters long before mtgox accepted my new password.
17  Economy / Economics / Re: When will it be possible to trade on MtGox again? on: June 21, 2011, 05:00:29 PM
Mtgox has been shoddily programmed since the start (unsalted md5 passwords, seriously? Md5 was showing signs of being broken 15 years ago), and there were a whole load of basic things that they could have done to prevented this hack having such a huge impact (eg. Circuit breakers anyone?).

I'm lucky enough to have taken all my money out of mtgox a few weeks ago, and I shan't be tradin with them again. I fail to understand why *anyone* would wish to trade with them again.
18  Bitcoin / Bitcoin Discussion / Re: I'm Kevin, here's my side. on: June 20, 2011, 10:36:31 PM
What's with so many people loving mtgox? they have "some responsibility" for writing crappy software, getting hacked via a dodgy auditor and getting the entire contents of the exchange sold off in 5 minutes? You're right, they do have the tiniest smidgeon of responsibility there...

The person whose account was hacked (if it was one person) is entitled to their Bitcoins and it's MtGox's responsibility to provide that to him. Kevin did nothing wrong making a large purchase of bitcoins, but now that he KNOWs the bitcoins were stolen, he's possessing stolen property, which can be a felony. The fact that MtGox's account was hacked makes all the difference here, as it makes the bitcoins which were traded stolen property.

If Kevin wanted, and as I'm sure a few other people have done, he could have purchased those coins, withdrawn every single one of them by exploiting the bug he identified, and then stayed quiet. Kevin, who is doing the right thing, will have 250k coins taken off him in the rollback, and would probably return those 600 coins if asked, other shadier people will have got away with some money, will stay quiet about it, and will get to keep it.

I think we're rewarding the wrong people here!
19  Bitcoin / Bitcoin Discussion / Re: I'm Kevin, here's my side. on: June 20, 2011, 10:22:36 PM
Does anyone still remember how MtGox handled the last situation where there was a large amount at stake for MtGox?

http://forum.bitcoin.org/index.php?topic=3712.0

That guy explained himself, was hounded by the community, MtGox barely bothered to respond, made some outlandish claims, froze funds and rapidly moved the whole operation to a different jurisdiction (Japan) after the guy finaly decided to get lawyers involved.

MtGox promised to inform the community! No news yet, and itīs been 6 months!

Wow, my trust for mtgox just went a little lower, didn't know that was even possible any more.

Any news from Baron on if he ever got his money back?
20  Bitcoin / Bitcoin Discussion / Re: I'm Kevin, here's my side. on: June 20, 2011, 10:11:26 PM
even I realize that these trades must be rolled back in order to prevent a loss of confidence by the investor group.

mtgox will restore confidence and keep the bitcoin economy alive.  It's a win-win.

I'll tell you what causes a loss of confidence: an exchange that takes arbitrary actions which it never specified in its user agreement to protect itself.

I got all of my dollars and bitcoins of of mtgox a few weeks ago. I've been generally unimpressed by the standard of mtgox software ever since it was first released, and this whole hacking fandango came as no surprise to me unfortunately.

With that said, MtGox does have some culpability.

What's with so many people loving mtgox? they have "some responsibility" for writing crappy software, getting hacked via a dodgy auditor and getting the entire contents of the exchange sold off in 5 minutes? You're right, they do have the tiniest smidgeon of responsibility there...
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