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Flavius, for a business with 20 employees, keeping 700k€ in your bank account is not a big deal.

Parabéns pelo tópico Daniel. É importante dar esses conselhos de boas-vindas.

Eu só seria um pouco mais "paranoico" no que diz respeito a segurança das tuas bitcoins. Pessoalmente, acredito que você nunca deve estocar suas bitcoins no mesmo computador que utiliza para navegar na internet. (claro, você pode estocar uma pequena quantia por questão de comodidade, como o dinheiro que você leva contigo no bolso, mas nunca uma soma significativa)

Navegadores são softwares cada vez mais complexos, verdadeiras máquinas virtuais, com diversos plugins etc. Por mais higiene digital que você tenha (e muitos não tem), você ainda assim corre o risco de ser contaminado por algo que passar por alguma vulnerabilidade do teu navegador. Já vi isso acontecer com computeiros que "vivem" na internet desde meados da década de 90, e que entendem de segurança digital.

Ou seja, se quer segurança, não pode estocar suas bitcoins no teu sistema principal de uso cotidiano.

As alternativas disponíveis são coisas como paper wallets, offline wallets (que podem ser simuladas com um sistema Live numa USB, tipo um Tails por ex., para quem não tem um computador só pra isso), ou até mesmo brain wallets para os mais aventureiros (cuidado, a qualidade da senha é muito importante aqui).
Admito que essas soluções são um tanto quanto geeks, e podem afugentar quem não fica muito à vontade com computadores. Eventualmente dispositivos como o Trezor ou o BitSafe estarão à venda para as massas, com interfaces bonitinhas e outras firulas, permitindo que todo mundo possa estocar bitcoins em segurança.

Ah, e lembre-se de sempre fazer backups criptografados na cloud. Use senhas fortes para teus backups. E senha forte = senha longa, não uma senha cheia de símbolos e caracteres estranhos que mais parece um texto em chinês que você inevitavelmente vai esquecer caso não a digite o tempo todo.

Visto que eles podem escrever e interpretar leis da maneira que bem entendem, isso é teoricamente possível, claro.
Mas seria no mínimo intrigante como eles formulariam a tal lei. Como definir Bitcoin exatamente, sem dar margens a interpretações amplas demais?

Enfim, como outros já disseram, até hoje não houve nenhuma pronunciação oficial do governo brasileiro no que diz respeito ao Bticoin*. Para efeitos fiscais, o mais apropriado é tratar como um investimento qualquer (ações, moeda estrangeira etc). O que por si só já me deixa com uma dúvida: se um residente fiscal brasileiro comprar uma moeda estrangeira e guardá-la por algum tempo, e nesse meio tempo ela se valorizar, o leão vai lhe cobrar imposto caso ele use essa moeda estrangeira para comprar coisas (sem passar pelo Real, usando diretamente a moeda estrangera para a compra)?

Como pode ver, há muitas dúvidas no ar ainda. E, infelizmente, acho que essas dúvidas inibem muitas empresas.

* Já houve uma pronunciação da CVM com respeito a um antigo fundo de investimento gerenciado por Leandro César. Esse fundo era em Bitcoin. Mas o pronunciamento da CVM não teve nada a ver com bitcoins em si, mas sim com o fato de que o Leandro não tinha a autorização do cartel para operar fundos de investimento.

PS: Obrigado por escrever esses artigos no IMB. Já estava me cansando das infindáveis discussões por lá. Acho que seus excelentes artigos vão facilitar a compreensão de muita gente.

That's false. The block size was limited because that was the easiest solution Satoshi decided to implement in order to prevent people from spamming the blockchain. That was intended to be a temporary solution.. you know, like the second one in this list: https://deconectat.wordpress.com/2010/09/23/top-funny-source-code-comments/

But eventually this limit will be lifted. That might provoke a fork of the network, since some people do prefer to force the scenario you describe (BTC not capable of handling all users transactions, having to operate like a SWIFT 2.0). But eventually most people would migrate to scalable Bitcoin.

Je ne connais pas trop, mais oui il y a des crackers.
En revanche, il faut que tu aies toujours au moins une idée approximative de ton ancien mot de passe (la longueur, les caractères utilisés, des morceaux que tu te rappelles etc). Sans aucune piste, un cracker ne peut casser que des mots de passes faibles (autrement à quoi ce servirait d'avoir un mot de passe? )

Je te suggère chercher d'aide dans le forum anglophone. Il y a plus de monde, et j'ai déjà vu des gens conseiller d'autres dans ta situation, qui ont finalement réussi à cracker leurs propres wallets.

Actually I think a "bitcoin for the masses" client should go the other way around: eventually hide all addresses from users, and just let them know they have "wallets".

All you need to know is that you have "wallets" or "accounts". Whenever you want to receive money in one of your wallets, your client generates you an URI, a QR-code or a simple file that contains a master public key for a deterministic key sequence. This master public key could be generated via a another "master-master-key", basically you'd have a grand-master-key for a wallet, which could generate different master keys for each time you want to produce a "bill".
You'd send this file/URL/QR-code to the payer. He'd add it to his payees' list, your name would show. Every time he wants to send you anything, he just chooses your name, and his client generates a new key from the master-key it has.

Users would only see something like an address is if they ever try to read the URI/file/QR-code - what they don't really need to. And once the secure payment protocol is implemented, a payee with a recognized certificate could even use URL shortners instead. A feature rich client could smoothly integrate with some shortner when applicable. And even if you don't want to pay for a recognized certificate, sending a self-signed key once is no less secure than sending a plain address.

My point is that the technical complexity and "weirdness/geekness" of addresses can be hidden, making it much more user friendly IMHO. And at the same time we make sure people would use Bitcoin addresses as recommended: one per transaction.

Wouldn't that make regulation automatically much stricter in many countries?

I wouldn't be surprised if in many places the law concerning foreign currencies happens to be more draconian than the laws concerning virtual goods.
Take Argentina, for example. Wouldn't that automatically push Bitcoin into its capital control, making it impossible for TradeHill to even start its venture?

And despite that, I don't think we should be seeking "state recognition".

À juger par le message d'erreur ça semble plutôt un problème avec ton pool.

Mais je ne mine pas, donc je ne sais pas vraiment.

How common are smartphones in Zimbabwe?
If they're not very common yet, what's needed for quicker Bitcoin adoption is something like Coinapult SMS wallet, at least while smartphones are not everywhere.

And, of course, an exchange would be necessary too. I'm not aware of any... is there an exchange in Zimbabwe, or an easy way for Zimbabweans to send dollars to foreign exchanges?

Actually, if the transfer of cell phone minutes is so easy, wouldn't it be possible to build a "cell phone minutes/BTC" exchange, instead of BTC/USD exchange? You would only need to be sure the cell phone operator would not close the exchange account for unauthorized use of its credits.


For the great majority of transactions you don't need more than 1 confirmation. Actually, if you know the sender, you don't need any confirmation at all.


Are you aware of Bitcoin Wireless? Perhaps you should contact them.

What you're calling "definition" is a set of "good practices" implemented in bitcoind and followed by most (all?) miners. But the protocol itself allows for 0-conf replacements. That's what I meant by "definition".

How do you know if an address has the money it needs to perform a transaction?

Plus, for the integrity of the chain, you must have at least all the headers. That's the only way to know which chain is longer.

But they wouldn't be undermining their own wealth, I'd say the contrary actually.


You're being overly dramatic here, admit it. Being able to replace 0-conf tx would not be such a bad thing.
I'd say that "selling" a false impression of security could actually do more damage. And the fact is that 0-conf are, by definition, replaceable.


But they'd still be able to do it.
First, if the merchant knows his/her customer, no major problem in accepting 0-conf.
If he doesn't, still, he can rely on insurance contracts that will on their turn have miners committing to mine a particular transaction instead of any replacement.
Besides that, merchants could also collectively - and voluntarily - try to blacklist double-spenders.
Sums all that, and you'll have very little fraud, if any.

Actually, why am I telling all these things to you? All these ideas are yours after all... hum... Friday evening, you're already drinking or something?

OKPay was not victim of a 0-conf, but a much more serious situation (the huge reorg caused by the 0.7 bug).
I think at least Satoshi Dice has already been the victim of a 0-conf double-spend.
But yeah, they are rare to the point of being negligible, if you compare them with CC fraud.

That doesn't change OP's point though: it's only safe because most miners are behaving as per the default bitcoind implementation. There's no strong guarantee that will remain being the case for long. (even then 0-conf would still remain relatively safe for many use cases, for example when you know your customer or when you can suspend your service easily)

I've never analysed the data myself, but I'd guess that honest splits tend to carry almost (if not exactly) the same transactions on each side of the split.

Those are very good points.


Such patch would not be that useful if it's not used by most relays and at least a few generators. But it's a start anyway.


It's sort of like GMail undo when you click Send. You have a few moments to change your mind, but once the mail is gone, you can't bring it back.
An eventual undo button should be disabled as soon as a confirmation is seen.


Good point. Warnings would be welcome.


Come on, you must admit that some double-spent of 0-conf transactions would never make Bitcoin collapse, that's an exaggeration. Particularly if people understand that a 0-conf tx can be easily undone.

What's not a very good way to think btw. What matters to your life is not whether your investment made you 5% or 5.000% but whether you earned $50 or $50.000.
It works when making savings to. For example, people are capable of making some effort in order to save $100 in a $200 purchase. But most people wouldn't even care about a saving of $100 when buying a house. And it's $100 in both cases, the exact same value...

(not questioning the display of the price in logarithmic scale though,... if you want to measure variance, that seems to make sense)

Indeed it is: How Fossil Fuels Have Greened the Planet (weird, I must click the google link to get through the paywall, the direct link doesn't work)

AFAIK they were stolen and were trying to repay their customers' losses with their profits. Not defending them on their mistake for losing that money, but isn't it clear that they can't comply with FinCEN? It costs lots of money, Even MtGox preferred to relay that responsibility to one of these 500K+ venture capitalist funded companies.

How could Bitfloor comply with that?