Author

I am Joannes Vermorel, founder at Lokad. I am also an engineer from the Corps des Mines who initially graduated from the ENS.

I have been passionate about computer science, software matters and data mining for almost two decades. (RSS - ATOM)

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Sunday
Nov242013

## Bitcoin, more thoughts on an emerging currency

Two years ago, I was publishing some first thoughts on Bitcoin. Meantime, Bitcoin has grown tremendously, and I remain an enthusiast observer of those developments. I had originally proposed a vision in 5 stages for the development of Bitcoin with

1. Mining stage
2. Trading stage
3. End-user stage
4. Merchant stage
5. Enterprise stage

Back in 2011, I had written that mining was taken care of. Well, since that time, Bitcoin has witnessed an explosion of the hashing power through the development of ASICs, that is, hardware dedicated to the sole purpose of mining Bitcoins. Mining has definitively emerged as an extremely specialized niche.

Bitcoin is now halfway through its trading stage. Two years ago, MtGox was so dominant that it was the closest thing to be considered as a single point of failure for Bitcoin. Meantime, many other exchanges have emerged: Bitstamp, Kraken, Btcchina … I suspect that MtGox holds no more than 20% of the exchange market share. Are we done with exchanges yet? Well, not yet, Bitcoins remain convoluted to acquire – I will get back to this point.

### Fade of interest, a fading danger but still the main danger

Price volatility, malevolent uses and adverse regulations are usually quoted as dangers faced by the emerging currency. I think that those threats have grown into non-issues for Bitcoins. Indeed, the very same criticisms can be made about most currencies and commodities anyway, and Bitcoin is now beyond the point where a roadblock could wipe out the initiative.

No, the one major risk for Bitcoin remains a fade of interest from the community. High-tech is a fast paced environment and few technologies survive a decade. However, considering the steady growth of Bitcoin in the public awareness, I am inclined to think that this risk, the one true danger for Bitcoin, is itself fading away.

### Bitcoin, a poster child for antifragility

Over the last two years, Antifragile from Nassim Nicholas Taled, is the most noticeable book I have given the chance to read. In particular, I realized that antifragility is probably one of the greatest and most misunderstood quality of Bitcoin. Bitcoin might seem complex, but it’s nothing but a protocol sitting on top of a shared ledger. Thanks to the present Bitcoin reach, the ledger itself – technically the blockchain – is probably the dataset in existence that benefits from the greatest number of backups world-wide. That part is safe, arguably orders of magnitude safer than the ledger of any bank.

What about the protocol then? Well, the protocol can fail, like any piece of software. It certainly did in the past, and most likely, it will fail again in the future. Let’s bring the case further, and imagine that instead of a simple glitch, someone manages to crack the protocol tomorrow, what would happen? Well, as it’s exactly what happened to Namecoin not too long ago, it’s not too hard to make a good guess. First, a corrupted blockchain would spread wreaking havocs in the Bitcoin ecosystem. Exchange rates would drop of 90% overnight, and then exchanges would simply stop operating. Meantime, within hours after the emergence of the problem, community developers, possibly members of the Bitcoin Foundation, would start working on a fix.

Depending on the nature of the weakness found the Bitcoin, fixing the problem would take from a few hours to a few weeks. Considering the amount of people involved, I fail to see why it would take much more than that. Indeed, Bitcoin is complex, but in the end, it’s not that complex, especially when compared to other popular open source projects such as Linux, Firefox or Open Office.

In the case of Namecoin, the terminal protocol bug was resolved in about 24h, and that’s Namecoin, an alt-coin with about 0.1% of the community traction of Bitcoin.

Then, once a solution is found, a new blockchain would be restarted from one of the many non-corrupted copies of the old blockchain still available. Depending on the depth of the problem, multiple and incompatible solutions might be proposed more or less at the same time by distinct developers. The market might even undergo a few competing solutions for a while, but then a “winner’s take all” effect will quickly push to oblivion all solutions BUT the leading one. Within a few months (maybe less), the exchange rates would have returned to their previous levels.

It’s Bitcoin as a ledger that is truly antifragile. The other part, the Bitcoin as a protocol is fragile and it is likely to be modified dozens of times over the next decade, each new version annihilating the previous version if the community consents to it.

If a massive protocol breach was to happen, many companies part of the Bitcoin ecosystem could go burst overnight: some exchanges might accumulate instant but terminal losses, a revised protocol could possibly make former hardware designs incompatible with the revised protocol, etc. The Bitcoin ledger itself is the only entity to be antifragile within the ecosystem, simply because many developers are personally vested in the preservation of this ledger.

Moreover, shocks do benefit to Bitcoin:

• Blockchain spam forced the community into making the protocol more resilient,
• Major thefts, the rise and fall of Silkroad, helped Bitcoin to make the headlines,
• Cyprus crisis undermined a bit the trust in the euros, again in favor of Bitcoin,
• Etc.

The next country printing its money into oblivion, the next bank failing with or without bail-out, the next country not to honor its debts … any of those events will further boost Bitcoin: not because Bitcoin will have succeeded at doing or succeeded at preventing anything, but merely because Bitcoin will have remained un-impacted.

In a way, betting on Bitcoin is betting on a degree of economic chaos for the years to come. A world of perfectly stable economies offering frictionless currencies does not need Bitcoin.

### When an Unstoppable Force meets an Immovable Object

While many trading options have emerged for Bitcoin, exchanging national currencies for Bitcoin remains a convoluted exercise; and, I suspect that it will remain non-trivial for a while, possibly a long while.

Indeed, pretty much everything in the banking system has been built around the notion of reversible transactions: the money on the bank is your’s, but only from a legal viewpoint. If a court decides that one of the transactions that originally funded your account was not legitimate, then the transaction can be reversed, and the money can change of owner based on third party interventions. With Bitcoin, ownership is a matter of knowledge. If you know the private key of a Bitcoin address, and if nobody else knows it, then you are the true owner of whatever Bitcoins this address has accumulated. It’s very physical process deeply uncaring for any legal considerations: no court order can recover a transaction made toward an address if keys have been lost.

This aspect explains why it remains almost impossible to use a credit card to buy Bitcoins, and why considerable delays tend to be introduced by parties even when wire transfers are involved. Exchanging cash for Bitcoins feels a more natural option though. A Bitcoin-to-Cash ATM is now already available in Vancouver. However, I suspect that ATM owners are heading for frictions. For any ATM model that takes off, bad guys will start buying ATMs for the sole purpose of reverse-engineering them with ad-hoc counterfeit money printed for the sole purpose of fooling this specific type of ATM. Indeed, bad guys don’t need to produce quasi-perfect counterfeit bank notes, merely counterfeit notes good enough to fool this one machine – a much easier task.

Again, with regular ATMs, it’s a non-issue. If someone manages to stuff an ATM with counterfeit money, the bank will simply cancel the corresponding transaction later on when the misdeed is uncovered. The bank has full control on its ledger.

### A store of value

When I discovered Bitcoin, I was inclined to think it would succeed because it made world-wide payment frictionless. Well, it’s certainly still part of the picture, but the more I observe the community, the more I believe it’s a positive but relatively marginal driving force.

Few people would argue that the growth of Bitcoin has been essentially driven by speculative investments. Then, according to the Bitcoin community wisdom, many would also argue that the ecosystem will gradually transition from pure speculation to more mundane uses, hence justifying high anticipated conversion rates. However,

• what if speculation stayed the dominant force not to be replaced by any other?
• what if Bitcoin did not need any alternative force to maintain its value?

Indeed, a shared yet incorruptible ledger may offer a fantastic intrinsic value on its own, as it gives people the possibility to save value without trusting any designated third party – trusting instead the community as a whole.

Gold arguably offers the same benefice, but in practice, gold is an impractical medium to make any payment; and, as a result, any gold transaction starts by converting the gold back to a local currency.

Then, why trusting a designed third party should be a problem, one might ask? Well, most currencies are simply not managed in the interest of the currency holders. China, Brazil, Russia and Argentina probably come top of the list here because of their respective size, but they are far from being the worst offenders. Then, even dollars, euros and yens are hardly managed in the best interest of currency holders.

Here, Bitcoin benefits from an ancient social pattern called the Gresham's law. According to the Wikipedia:

Gresham's law is an economic principle that states: "When a government overvalues one type of money and undervalues another, the undervalued money will leave the country or disappear from circulation into hoards, while the overvalued money will flood into circulation." It is commonly stated as: "Bad money drives out good".

This law has been quoted many times about Bitcoin, but its consequences are usually misunderstood. Many detractors argue People are just hoarding Bitcoin, instead of spending them, which will be the downfall of Bitcoin. This observation is partial, and I believe that the conclusion incorrect too. Note that Bitcoin can still fail, but not because of this (see above).

A more accurate observation would be Many, if not most, are hoarding Bitcoins until they have an actual need to spend them. Meanwhile, those people just keep spending whatever non-Bitcoin currency they have. This behavior exactly fits the Gresham’s law, but what does it imply for Bitcoin?

First, merchants should not expect too many people rushing to spend their Bitcoins. Most people will keep spending their non-Bitcoin currency as long as they can. However, as accepting Bitcoins is an inexpensive option, there are little downsides in accepting Bitcoins - especially if Bitcoins are immediately converted to the local currency. Second, the more people keep their coins, the more the exchange rate will rise, due to simple market mechanics; thus, actually preserving the value storage property of Bitcoin.

At this point, detractors would argue that if there is little exchanges through Bitcoin and if it’s only about hoarding something that has no real value, how could this something be worth anything? This brings me back to the ledger (i.e. the blockchain). The one distinctive innovation brought by Satoshi Nakamoto is to make the world realize that a fully decentralized and yet incorruptible ledger was possible. The Bitcoin ledger is unique and it’s is what gives Bitcoin its value.

What people really owns when owning Bitcoins is a quantified amount of favors that could be given back from any member of the community; as long community interest has not faded, and it can be a valuable privilege – hence, not needing further benefits to justify the value.

### Alt-coins will drive the evolution of Bitcoin

As an asset, what is the value of the Bitcoin protocol? Well, zero. Anybody can fork the source code, almost 2000 already did. Anybody can restart an alt-coin variant, dozens already did. While Bitcoin can be arguably estimated as invaluable to mankind, the protocol itself has zero market value: nobody makes money by selling the protocol.

The market value is in the ledger and only in the ledger, and this is why alt-coins are unlikely to gain any significant market value: they recycle the bulk of the Bitcoin protocol (the value-less part) while ditching the blockchain (the valuable part).

Namecoin is barely an alt-coin, because it addresses a very different problem; and that’s precisely because it does not compete with Bitcoin that it managed to gain traction.

Nevertheless, alt-coins represent an incredible opportunity for Bitcoin. Through experiments with alternative approaches, alt-coins are producing the knowledge that will make Bitcoin more secure, more usable, leaner, etc. Alt-coins, by being fragile experiments, directly helps Bitcoin in becoming more antifragile.

For example, Zerocoin brings an unprecedented level of anonymity in transactions by introducing rocket-science zero-knowledge cryptography in the protocol. From the Bitcoin perspective, there is absolutely no need to rush to import Zerocoin into the protocol. After all, Bitcoin has been striving without it so far. It’s much more reasonable to remain a passive observer for a (long) while, to let Zerocoin take all the bullets as bugs and flaws are uncovered, to let the Zerocoin community patiently address performance issues; and then, once Zerocoin has fully matured, to upgrade the Bitcoin protocol leveraging all this hard-won knowledge.

Thus, from a currency holder perspective, it means that alt-coins are doomed with high probability, because they won’t be able to preserve any technological advantage over time, bringing the competition back to a competition between ledgers where Bitcoin will only grow stronger over time.

### Preserving Bitcoins

Since Bitcoin is about storing value, foolproof ways to secure Bitcoins is a critical ingredient. Two years ago, I was already indicating this challenge was not specific of Bitcoins: it’s just incredibly convoluted to operate a computing environment that you can fully trust. Long story short: you need air gaps, but it’s harder than it looks.

Furthermore, the overall amount of trust that people should have in their computing devices - notebooks, phones, servers in the cloud – has rather gone downward since the Snowden revelations. Thus, I am inclined to think that many successful ventures of the end-user stage will be Bitcoin appliances, that is, hardware devices designed for the sole purpose of dealing with Bitcoins. The Bitcoin Card and Trezor are both promising appliances, and I suspect there is room for a lot more contenders in this market.

Indeed, as most people invest in Bitcoins, it’s fairly reasonable to assure that most of those people will be inclined in spending a bit to more to secure their investment.

The widespread availability of Bitcoin appliances that have gained the trust of the community will be the sign that the end-user stage of Bitcoin is taken care of.

### Annex: More technical considerations

Instant transactions are coming without much effort. It takes half a dozen of blocks to gain an absolute confidence in a Bitcoin transaction, which means about 1h of delay. Many people see this aspect as a design failure, which prevents most live payment scenarios. However, if one is OK from relaxing the constraint from absolute confidence to quasi-absolute, then instant transactions can be made very secure, arguably a lot more secure than credit cards transactions (because of chargebacks). All it takes is an online service that aggressively spreads the transaction over the network while in the same time it aggressively monitors any double-spend attempt. Such a service does not exist yet, but it’s not the most pressing issue for Bitcoin either.

Scalability is a very addressable concern. Scalability is frequently presented as a core design flaw, that is, if Bitcoin starts gaining traction, it will fail because it won’t be scalable enough. (Disclaimer: argument from authority) My own experience in teaching distributed computing and tackling Big Data projects for year indicates is that scalability is never a terminal problem. Scalability problems are straightforward problems merely needing patience and dedication to be solved. Furthermore, many developers just love tackling scalability challenges well beyond market needs. That part of Bitcoin is probably very safe.

Tuesday
Dec202011

## Instant transfer with Bitcoin but without 3rd parties

Update 2012-05-17: Double spending can be made extremely difficult through quasi-instant double spending attempt detection. See TransactionRadar.com as an illustration. I now believe that the ideas posted below are moot, because early double spending detection is just the way to go.

Bitcoin is a crypto-currency (check out my previous post for some more introductory thoughts) that provides many desirable properties such as decentralization, very low transaction fee, digital-native, ... However enabling instant payment has not been a forte of Bitcoin so far. It's very noticeable that people did even raise funds to address this problem with a trusted 3rd party setup.

In this post, I will try to describe a convention that would offer instant (1) secure (2) decentralized (3) transactions with Bitcoin (4).

Let's start by clarifying the scope of this claim:

1. Instant. There is no such thing as real-time on the Internet, if only because of speed of light. Here, I am considering as instant anything below 10 seconds, which would be sufficient for the vast majority of the mundane use of a currency such as shopping.
2. Secure. With Bitcoin, a transaction can be propagated in the network within seconds, yet, the transaction only becomes secured - aka with no further possibility of double spending - once the transaction has been included into the blockchain (6 blocks inclusion being the default of the Bitcoin client). Obviously, this requirement somewhat conflicts with the previous one, because 6 blocks represents about 1h on average (10min per block being the target speed of Bitcoin).
3. Decentralized. The solution to reconciliate 1 and 2 should not rely on a trusted 3rd party. I hold no grudge against BitInstant, but if a solution exists to do the same thing without middlemen, then I believe it will only make Bitcoin stronger.
4. Bitcoin. The solution should preserve the Bitcoin protocol as it exists today, requiring no upgrade of the community, except for those who would like to leverage instant payments. It's a convention in the usage of Bitcoin that I am referring to: it fits into the existing protocol spec. Those who don't want to follow this convention can safely ignore the whole thing.

Disclaimer: I am neither a cryptograph nor a security expert, merely an enthusiast Bitcoin user.

The core idea of my proposal is to introduce a twist in the notion of security: instead of a strict prevention of double spending, let's make double-spending more expensive that the expected benefit. Indeed, if double-spending becomes possible but only a steep cost (cost being expressed in Bitcoin too) then there is no incentive to actually make any widespread use of the double-spending trick for instant payments. With this twist, we accept the possibility of double spending, but only because it's highly innefficient for the attacker. It will not prevent a crazy attacker to do some damage, but from a global perspective, the overal damage through this twist should stay insignificant (because there are so many better ways to wreak havoc anyway if you're willing to spend money on the case).

For the convention that reconcilitate 1, 2, 3 and 4, I use two ingredients:

• A Bitcoin address that is provably expensive: the setup cost of the address is X BTC.
• A mechanism to check that garantees that no double-spending attack to place for the address in the past (blockchain-wise).

Usual Bitcoin addresses are quasi-free (the CPU cost to generate a new address is negligible), but it's not difficult to produce a Bitcoin address that comes with a provable cost. The easiest way is go for monetary destruction with a transaction that targets /null. Yet, destroying coins is not entirely satisfying.

Thus, in order to prove the value of the address AX, I propose to have a transaction, originating from a single address 1A only (only 1 input) that by convention redistribute its value to the coinbase address (*) of 10 consecutive blocks that are less than 1 month old (at the time of the proof).

(*) It's the address of the first transaction of the block used by the miner himself to capture its reward.

Indeed, we cannot rely on transaction fee alone to prove the cost of address, because a miner could decide to create a ficticious high-fee transaction in a block - fictictious in the sense that the fee would cost nothing to the miner, who would immediately recover the fee through the ownership of the block.

Yet, by targeting 10 consecutive blocks, we prevent any miner to fully self-reward itself with the transaction. Indeed, blocks are assigned based on a lottery where the odds are proportional to the processing power injected in the process. A "smart" miner would be able to target one (**) of his block, lower the cost by 10% which does not compromise the pattern (the cost remains very real).

(**) Some super-heavy mining pool, like deepbit, could push the leverage further; but having a single mining operator representing more than 1/2 of the total hashing power of Bitcoin is a big problem for Bitcoin anyway; so I am assuming here that no operator has more than a fraction of the total computing power available.

Then, the 1 month old restriction is just there to increase the odds that the coins do not get lost. Indeed, since the owner of the targeted addresses do not expect further funds to be pushed on those addresses they may not even monitor them once they have been emptied. Yet, with the 1 month delay, the lucky reward will not stay unnoticed.

Another argument in favor of rewarding the coinbase addresses is that it increases the incentive on mining efforts, hence strenghtening Bitcoin as a whole.

Based on the convention established here above, we have now a way to prove that a Bitcoin address did cost at least X BTC to her owner. Yet, we still need a way to be sure that no double-spending attack has already been done.

Here, the intuition is the following: you cannot prevent double-spending with instant payment (aka without block validation), but you can expose afterward the double-spending attack which will destroy the trust invested in the provably expensive address.

Let Alice be the honest merchant who offer instant Bitcoin payment; let Bob be the bad guy who trying a double-spending attack on Alice.

At the moment of the transaction, Bob gives to Alice the content of the transaction Tx1 that has 1B as input (the address of Bob, proved being expensive) and 1A as output (the address of Alice). Yet, at the very same time, Bob is issuing another transaction Tx2 that empties the address 1B. As a result, after a while, Alice realizes that Tx1 has been rejected.

It's now time for Alice to retaliate by exposing Bob. In order to do that, Alice produces a small dummy transaction to herself where the transaction Tx1 in recursively embedded as data though a convention based on OP_DROP. (***) Once the transaction Tx1 is exposed, the community of merchants, who like Alice, accept instant transaction withness that 1B cannot be trusted any more because the cumulative effect of the transaction Tx2 going out of 1B and of the exposed transaction Tx1 (which never made its way to the block chain) leads to a negative coin amount on 1B.

(***) For the sake of concision I am leaving out the tiny specifics of how exactly should this recursive transaction embedding be implemented. Anyway, based on my understanding of Script, it's perfectly possible to recursively embark a transaction (treated as data) into another transaction.

At this point, we have a system where Bob, the bad guy cannot hurt Alice the merchant (recipient) without getting some retaliation. Yet, what if Alice is a bad merchant and Bob the honest client? Could Alice hurt Bob just for the sake of breaking the community trust into his provably expensive address 1B?

We need one final touch to the convention to protect Bob the sender from a false accusation of Alice. In order to achieve that Bob should make sure each emitted transaction Tx1 from 1B, his provably expensive address, is broadcasted to the network, and not just given to Alice. By doing this, Bob ensures that Tx1 will make its way to the blockchain and prevents Alice to report 1B as dishonest (to be safe Bob is better off putting some transaction fee in Tx1 that guarantees a speedy chain inclusion).

### Implementating the convention

As far I can tell, the proposal does not involve any breaking change. Ideally, the convention would make its way to the Bitcoin client (or a dedicated fork) to support 3 extra features:

• Spending BTC to increase the trust level on a particular Bitcoin address.
• Performing instant transactions channelled through the "expensive" Bitcoin address.
• Reporting the "cost" of the address for the incoming transactions.

Then, there is many small details that would need to be polished such as the delay for the community to decide whether trust is lost on an address after being reported. Also, the convention as a whole can also probably be polished further.

### Anonymous payments

This convention would be one step further is making Bitcoin less anonymous that it is today. Considering the scope of application of instant payments, it does not seem (to me) too much of a problem. If you really want to stay anonymous, then, entering a retail store isn't top notch anyway. Alternatively, for eCommerce, the 1h payment delay is mostly a non-issue (except maybe for pizza delivery).

### In real life

Instant payments are needed for small purchases: you typically don't need to transfer both a big amount AND to do it instantly, it's either or. To accept (or not) whether an instant payment of X BTC made from a proved Y BTC address should go through instantly should be left to the merchant itself.

With a 10 BTC proof, it would reasonable to accept instant payment up to 10 BTC (maybe a bit less assuming a self-serving miner scenario). Coordinating triple-spending (or more) in real life seems complicated (but not impossible) but I seriously doubt people would actually bother for such a complex scheme except to demonstrate its feasability. Indeed, the stakes would be very limited anyway, as anything large would go the usual route of non-instant payments.

Then, looking at recurring customers payment with the same address would be also a way to gradually increase the confidence cap (from the merchant viewpoint) for instant payments even without asking the client to increase its proof.

Compared to a rough 2% middleman fee (based on pricing of BitInstant), I feel that the provably expensive address would be amortized in less than 1 year considering weekly purchase. Not a deal breaker, but still an option probably worth having a look at considering the positive side-effect on the mining side.

Wednesday
Aug032011

## Bitcoin, thoughts on a nascent currency system

Bitcoin is a fascinating concept, in short, it's a crypto-currency backed by nothing other than raw processing power and geeky enthusiasm. For those who've never heard of it, you can have a look at the introduction provided by the Bitcoin community itself or by The Economist.

This currency seems to trigger a much positive reactions than skeptical ones. My personal stance is very inclined in favor of Bitcoin, and I have invested a conservative amount of Euros in exchange of Bitcoins. Granted, nothing that would too troublesome even considering a 100% loss of value for those Bitcoins.

A lot have been said already about Bitcoin, so I will not go through the routine discussion of pros and cons, but merely make some observations.

### Bitcoin vs Credit Cards and Classical Banking, the long term value

A good deal of interest in Bitcoin is strictly speculative: people go for Bitcoin thinking they have a good chance of cashing out. Yet, when it comes to evaluate the value of venture of any kind, I am a strong believer of the Guy Kawasaki credo: does it make sense? Is the world a better place with Bitcoin than without? Indeed, making a speculative profit is not enough, Bitcoin has to improve the world in some tangible ways.

Here I believe that Bitcoin addresses a very deep problem: how to pay or receive money without involving either an expensive physical process (meeting and exchanging gold, goods, ...) or an expensive middleman (your bank, your credit card operator, PayPal, ...).

To a web entrepreneur, the current banking system looks like a 19th century legacy setup:

• About 4% (1) of my money gets consumed through system friction.
• It takes days (2) to complete anything that does not go through credit cards.

(1) Indeed, there are many costs that pills up (rough estimates):

• 0.5%, fees of the consumer bank account (explicit or not),
• 1%, fees of the credit card owned by the consumer,
• 2%, merchant fees for any online payment,
• 0.5%, fees of the merchant for its own bank account.

(2) International wire transfers with a bank routing in the middle where a 7 to 10 days delay is pretty much the standard.

And yet, in my experience there is not so much to be done about this friction, at least not if you're just Joe the Plumber or a small business. Marginally lowering those costs through negotiations with the bank is possible if you have leverage (that is to say money) and a lot of patience; but there is so much one side can do because both sides (payer and receiver) are paying fees anyway.

The long-term promise of Bitcoin is to bring down this 4% friction to 0.1% or less, and to reduce payment latency from days to minutes, possibly seconds with a healthy competitive ecosystem of trusted 3rd parties. Indeed, Bitcoin is not natively designed for low latency transactions, but Bitcoin can be complemented by low latency services (backed by Bitcoin) if the need arises.

Anecdotal evidence: When I purchased Bitcoins on MtGox a few days ago, the sole wire transfer from France to UK cost me about 4% (EUR to GPB conversion included), plus the transfer took 8 days, because the receiving bank in the UK had a multi-day downtime of one of their system.

### Weaknesses of Bitcoin

When it comes to assessing the weaknesses of Bitcoin, most people discuss the possibility of breaking the underlying cryptography, or swarming the network with some overwhelming computing power. Yet, Bitcoin has been designed to be natively resilient against this sort of attacks, and very capable people are working hard to make Bitcoin even more resilient. Hence, I am not too worried here: the Bitcoin community is now big enough to make those sort of attacks really complicated.

Anecdotal evidence: I have tried to mine about 0.01 BTC through Deepbit.net and on my GPU enabled laptop it was taking about 30h. Naturally, I gave up before the end of the experiment, as it was pointless to waste further electricity. Bitcoin mining has reached the state of being vastly unprofitable for everyone but the experts, which is good. It means Bitcoin had reached the point of diminishing returns where printing money (aka mining) is only very marginally profitable.

The most critical threat for Bitcoin is something simpler and stronger: a potential fade of interest, which may vastly hinder the tooling ecosystem to mature. Fade of interest would not annihilate Bitcoin, but it would make it stagnant. Then, in the innovation trade, being stagnant is the closest thing to being dead.

For the short term (next few months), my No1 concern is that a tiny few individuals such as the enigmatic Satoshi Nakamoto may possess +100k BTC (or this guy with 370k BTC). And no, the problem is not that the system is unfair - being unfair does not hinder economical success, quite the opposite actually. The problem is that each one of those individuals has the power to disrupt the emerging usage of Bitcoin. As a matter of fact, the first Bitcoin market crash was not the result of a weakness within the protocol, but the result of a not-fully-secured wallet within a trading system. A lot of early adopters are moving around with thousands of BTC, and each one of those, willingly or not, may disrupt the Bitcoin trading by simply getting their wallet stolen. A similar analysis goes for all the emerging companies supporting the Bitcoin economy that are really lacking the expertise needed to operate properly (ex: the now infamous MyBitcoin.com downtime fiasco). Those bumps are not for the faint hearted, and are likely to slow down the Bitcoin adoption. As time goes, this sort of problem will fade through survival of the fittest, but a couple of Bitcoin crashes should be expected.

For the mid-term (6 months ahead to 2 years), the most difficult operation will be to transition the Bitcoin community from mining stage to trading stage, then repeat the process again from trading stage to end-user stage (see below, for the detail of the phases) - and do those transitions without loosing commitment and enthusiasm of the people who contribute the most to the Bitcoin community. Basically, as long there are smart people enthusiastic about Bitcoin, Bitcoin will keep growing; but the attention sharing economy is a harsh mistress, and the community interest might jump to the next revolutionary idea just as well. See the law of conservation of hype as a practical illustration. Bitcoin has successfully attracted a horde of miners. Now this horde needs to involve into the next stage, as mining earnings are marginalized.

For the long term (2 years), assuming Bitcoin interest has not faded already, direct Government interventions - for whatever reasons (*) - may kill the community. Outlawing Bitcoin would be hard to enforce to its fullest extent, at least if Internet still exists, but flagship companies supporting Bitcoin are easy targets. It would also be easy to spot any company publicly accepting Bitcoin as payment method. Again, the problem is not Bitcoin annihilation - which seems a remote possibility - but rather Bitcoin undergoing a fade of interest if its community has to go underground.

(*) Until 1996, all encryption methods were banned in France, classified a warfare materials. As a result, encryption usage was close to inexistent despite obvious benefits.

### Assessing a global value for Bitcoin

Many people looking at Bitcoin make the naïve assumption that BTC mined X USD per BTC gives any reasonable assumption of the overall market value of Bitcoin. This approach is misleading. First, we don't know for sure how many BTC have been lost already. Super early users were not really treating BTC as a real currency, and it took more than 2 years for Bitcoin to take off. I suspect that many early casual miners have not properly preserved their wallet. This could account for 1M or 2M BTC being lost already (warning: this number is vastly unverifiable).

Second, those who've read Making Money  - which I strongly recommend - know that the real long-term backing of any currency is the people behind it, possibly as unwilling taxpayers (but I am digressing). Granted, Bitcoin has no magical Golems backing the protocol, but they have about the next best thing: a enthusiastic, dispersed and growing community of geeks working hard to make of Bitcoin a success.

#### Bitcoin v3.0 - Merchant tools

If Bitcoin gets adopted by a sufficiently large amount of people, then it will start getting the interest of retail folks. There are already a few eCommerce out there supporting Bitcoin, but it's still very niche. The design of Bitcoin offers unprecedented opportunities to support micropayments that were simply not tractable with classical systems. Indeed, anything below $20 is considered as a micropayment by Visa, and there is no widespread electronic solution out there for payments below$1. In comparison, Bitcoin would easily scale down to \$0.01 payments (or rather the equivalent amount in BTC) with only a marginal friction. Yet, in order to grab those opportunities, it will take some serious Bitcoin-powered merchant systems, as complete automation is required. Offering to any (non-geek) merchant all the tools he/she needs to receive and process Bitcoin payments is the v3.0 milestone.

#### Bitcoin v4.0 - Enterprise tools

No matter the success of Bitcoin, large companies will probably be among the latest entrants in the Bitcoin economy. In order to make Bitcoin useable in corporate environments, it will require a lot of support from the software industry. For example, there is nothing yet in the Bitcoin software ecosystem that would enable an enterprise to grant rights to people to operate within spending quota, possibly requesting multiple approvals if a spending goes over a certain threshold. Naturally, the same Bitcoin system would also need to be seamlessly integrated into the primary accounting system in order not to drive nut both accountants and auditors. Getting Bitcoin corporate-proof is the v4.0 milestone.

### So what next?

Bitcoin is still in the middle of trading stage but, for those who are inclined in giving Bitcoin a chance to establish a very low-friction currency system, the most simple contribution is not to purchase Bitcoins, but simply to start accepting Bitcoin, which is exactly what my company, Lokad.com, started doing.