Showing posts with label hack. Show all posts
Showing posts with label hack. Show all posts

Monday, August 15, 2016

Secondary and debt markets for exchanges

Secondary and debt markets for exchanges

As discussed last week, Bitfinex has followed through with their bail-in and gave all of their users a 36% "haircut". While not ideal, with the right approach and conviction, this might be a way for the exchange to eventually right their customers. The idea is not new - I recall discussing something similar a few years ago when another big exchange was not measuring up...

MtGox's secondary market


MtGox, the poster child of why one shouldn't trust exchanges with one's BTC, has officially shut down in 2014. However, months before that you could already see some red flags popping up that something was going wrong. MtGox started having some fiat withdrawal problems, and as a result, its market was off by 10+% and ripe for arbitrage. Some people could make a tidy profit churning money around, provided they could get their fiat out of the exchange.

A few months later, the situation got worse - MtGox has officially halted both its bitcoin and fiat withdrawals altogether. However, probably due to some interesting code optimisation, someone figured out that if you withdraw bitcoins straight into a deposit address of another MtGox account, the funds would be transferred without creating a transaction on the blockchain. It looked like that functionality was governed by the "MOVE" API call, rather than "SEND". This tiny functionality was enough for someone to build an entire secondary market for MtGox before the whole exchange went under.

While I can't find any reference to what the site was (EDIT: the website was Bitcoin Builder, as pointed out by /u/samurai321), as the news of MtGox collapse has probably buried it in the sands of time, I remember it being a simple BTC-MtGoxBTC exchange. One could deposit actual bitcoins and trade them for bitcoins owed by MtGox that were moved to the secondary market's address. It allowed some people to get rid of their coins frozen at the exchange and cash out to the safety of the wallets their own, while letting others speculate on whether or not MtGox would be going under. I remember seeing the price reaching a level of 30+% discount on the market, which is fairly comparable to the current Bitfinex scenario...

Decentralised secondary markets


After MtGox collapsed, I haven't seen a similar secondary market pop up anywhere. The closest thing that comes to mind is being able to trade Bitstamp's IOUs on Ripple, which might be an ideal approach for trading exchanges' debt (at least provided the exchange doesn't run into new hacks). If Bitstamp was to go under, you could still trade about 1.5M USD and 2k BTC of its issue on the decentralised exchange nearly indefinitely. Figuring out its USD-USD and BTC-BTC exchange rate against an operating pool could be a clear gaige of confidence in the platform - if there were talks of the exchange recovering, the price might get closer to parity, or go away from it in the opposite case.

At the same time, such a secondary market might be used for something more morally muddy...

Buying one's own debt


Say Bitfinex's tokens were tradable during the hack. Before everyone knew how much was lost percentage-wise, the market would be wild with speculation - you probably could buy bitcoins at 50+% discount, perhaps even at 90% discount if the fear would set in. Now, if Bitfinex was aware of such a situation and knew how much deposits they could actually cover, they could try buying up their own debt for pennies on the dollar before the haircut was to take place. This could allow them to buy off some of their debt at a discount, reducing their obligations to their customers and therefore creating a theoretical profit.

Such a scenario would be highly unethical and I would guess highly illegal, but I wouldn't be surprised to see something like this happen sooner or later in the Bitcoin world. Instead, let's imagine some more ethical approach Bitfinex could act on their current situation...

Slow debt repayment


I'm not sure how Bitfinex structured their token program as I don't use the exchange. However, a good approach to eventually righting everyone would be for them to convert everyone's BTC balance into those tokens. At any time, the users would be able to cash the tokens in and get actual coins, minus the haircut. With each token converted, their obligations would decrease.

The tokens would also be tradable on the exchange itself for actual coins, creating a market for the debt. Anyone wishing to speculate would be able to trade the coins for a value between the haircut discount and 1BTC. The price would have upper and lower bounds, but could fluctuate in between.

If Bitfinex was diligent and set on repaying the debt by eventually buying up all of the tokens, they could publicly declare their strategy of doing so - perhaps a portion of their monthly income would go directly into purchasing the tokens from the market at the spot rate. With every purchase, the amount of tokens in circulation would decrease, thus the ratio of their bitcoins earmarked for buying back the tokens to the actual amount of tokens would increase, making the haircut smaller and smaller. Gradually, the gap between the value of the tokens and the real coins would shrink so much they could convert the tokens themselves straight into coins at a 1:1 ratio and remove them entirely.

In the end, the amount of coins you would get back would rely only on how quickly you need them - you could get them today for 36% off, perhaps get them for 30% off in a year, or get a full amount in a decade. The market would decide what the future value of the tokens would be, and with each month (and perhaps with each trade if some fees were to be maintained for this market), the debt would be slowly repaid.

In the end, this is an optimistic scenario assuming the exchange could earn back millions of dollars worth of coins before the company would go under. Similarly, if you believe the value of bitcoins will go up, the debt may never be repaid - the value of the coins left to be repaid could be going up as the number of the coins would be going down thanks to the increasing price.

One way or the other, it would be a really interesting case study if Bitfinex was to implement something like this...

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Monday, August 8, 2016

Avoiding Bitfinex scenarios with Voting Pools

Avoiding Bitfinex scenarios with Voting Pools

This week, a high-profile Bitcoin theft took place at the Bitfinex exchange. The attacker reportedly stole 119'756BTC, worth about 70.5M USD. Those funds were held at a 2-out-of-3 multisignature wallet - one key was held at Bitfinex's server, another was kept by BitGo, and a third was a backup key held offline by Bitfinex. From what the reports say, the hacker was able to get their hands on the first key, as well as the API credentials required to authorise BitGo to process the withdrawal. With no additional safeguards, they were able to drain the hot wallet and land themselves around the number 2 spot of the biggest Bitcoin theft to date, after MtGox.

The scenario is still unfolding, so there are a lot of theories still floating around as to why the situation was allowed to take place. Some have speculated Bitfinex was forced to keep all of their coins in a hot wallet due to CFTC's ruling (as Bitfinex was not a registered futures trading platform), although it seems that the change was made before the ruling. Bitfinex also unveiled a plan for a "bail in", wherein everyone's assets would be devalued by about 36% so the exchange could continue operating.

Since Bitcoin's past seems to be littered with theft, I would like to have a look at one possible solution to minimise such high-profile hacks:

Voting Pools


Voting Pools is an idea proposed by Open Transactions, a Crypto 2.0 platform focused on notaries issuing IOU tokens and other financial instruments. The main issue such systems have to cope with is securing the cryptos, currencies and commodities underlying the assets circulating on the platform - an USD IOU is only useful if you can redeem it for real USD at the end of the day.

The way Voting Pools help secure users' funds is through shared responsibility from competing actors. Multiple exchanges of similar size would group together in a pool and secure one another's funds through multisig and a legal agreement to share responsibility in an event of a loss (be it from theft or one of the exchanges trying to run off with everyone's money). The multisig would be distributed in such a way that any one actor would not be able to control even their own money, and the system being robust enough to handle a loss of some keys (2-of-3, 3-of-5, 4-of-5, etc.).

This setup would make sure that a critical failure of one actor would not compromise the system. Even if one of the exchanges would burn down, get hacked, or the owner would decide to run away with all of the private keys, they couldn't do anything. The other exchanges would take over the responsibility and secure all of the funds to be able to pay all of the failed exchange's customers without suffering a loss of their own funds.

More importantly, however, this solution also forces every participating company to not only police themselves and ensure they have the most adequate security practices in place, but also to look at one another. When your own money is on the line, you will make sure everyone is keeping up with the rest of the pack in terms of keeping the money safe. Since the exchanges would still be competing with one another, they would have every incentive to expose other actors in the voting pool that are compromising the security.

Beyond that the full implementation of Voting Pools also necessitate that the exchanges would open up their transaction logs to one another to make sure everyone knows how much every customer is owed in case of a database wipe or the exchange vanishing from the face of the earth. This is pretty much automatic when it comes to gateways on a public ledger like Ripple or some shared permissioned blockchain, and it shouldn't be too hard to accomplish if an exchange already creates a strict and timely Proof of Solvency. That being said, it is pretty much unheard of for a normal Bitcoin exchange to do that currently, which might make it more problematic.

Having access to a full, real-time set of transaction logs the participants in a voting pool have everything they need to not only be able to settle with every customer in case the exchange goes under, but they can also police the exchange in real-time and raise flags in case of discrepancy. If exchange's liabilities exceed their assets, all withdrawals can be automatically haled until the matter is resolved. Large withdrawals, sudden market crashes and balance changes could similarly raise a lot of flags (to avoid another MtGox scenario, wherein a hacker crashed the market to be able to bypass the $1000/day withdraw limit).

Conclusions


All in all, voting pools would force a strong degree of transparency on every actor and couple that with multiple security teams making sure the system is secured against a growing number of hacks. While the participating exchanges would sacrifice their business data secrecy to their direct competitors, security through obscurity is never a good approach.

Monday, June 20, 2016

Perfection or bust - the rise and fall of The DAO

Full disclosure - I own some ether and I have put some of it into The DAO presale. I don't think it coloured my view of the situation, but I feel it's better to be open about such things.

The DAO has made a lot of waves recently. First - last month when it became the largest crowdfunding project in history, at one point surpassing Star Citizen's 116M USD (although it might be partially due to ETH exchange rate fluctuations). Second time - earlier this week when the DAO was hacked. So lets start from the beginning and have a look at the rise and fall of The DAO.

DAOs, in general


DAO, or Decentralised Autonomous Organisations have been a fairly nebulous concept in the crypto space for awhile. They basically are computer programs that run as an organisation, using its code as law. They can hold digital assets and money that can be spend on various projects, services and other digital assets.

Some have proposed to use DAOs to create a rudimentary self-sustaining decentralised organisations. Such programs would actually use their resources to hire people to improve them. I've heard this concept described first during the 2013's Money2020 Ripple conference, and I would consider BitShares to be one of the first self-sustaining DAOs.

Of course, with the current level of cryptocurrency technology, the DAOs are very limited in scope. They can't be as sophisticated as modern AI running on supercomputers, and since code isn't lawfully binding - the various DAOs have to rely on humans to interface with the outside world.

In theory, DAOs could create a lot new jobs. As @aantonop put it though:

TheDAO will create many jobs. First for people like me who have to explain what the hell it is.

The DAO


The DAO (holding a very generic "temporary name", which it probably won't escape from), created by Christoph Jentzsch, the founder of Slock.it, was set out to be one of such self-sustaining DAOs. It was set up to be a quasi-venture-capitalist-fund. As with many token crowdsales, it was skirting the borders of the law - allowing anyone to invest, not doing any KYC, promising "benefits to the DAO Token Holders", without outright selling securities.

The project had support from a number of high-profile members of the Ethereum Foundation

The DAO started operations by selling its tokens for ETH. The promise was that later the ETH would be used to fund various projects and try to extract value from those projects to the DAO itself. The DAO also had a mechanism to upgrade itself to newer versions of the code. The entire process of both spending money and code upgrade would be governed by the token holders voting. Every vote would be proportional to the amount of tokens held.

By the end of the crowdsale, The DAO has raised 8.26M ETH, more than 10% of the total coin supply.

In theory, The DAO could've been a very strong player in the crypto space. Even if it would spend 10% of its funds just funding early stages companies, it could give out 100k USD to 100 different companies and probably have great ROI by the end.

However, there was a bug in the code...

The exploit


Around 2016-06-17, news broke that The DAO's balance was being drained. Quickly there was a call to all exchanges to stop trading the tokens and Ethers while the situation is being resolved.

As it turns out, The DAO had a small bug in it (discussion, technical overview). They managed to make a recursive call to a function and use that exploit to start draining The DAO of its ETH. Before the attack stopped, 3.6M ETH was extracted, worth about 50M USD give or take 20M due to wild price fluctuations.

The attack stopped around the time Vitalik released a blog post about how Ethereum will be handling the exploit. In the end it was decided that Ethereum will not roll back, instead creating a soft fork preventing the drained ETHs from being spent. The coins would also apparently be reimbursed and everyone that put their money into The DAO would be getting it back.

The following day, we actually got a statement from "The Attacker" about the issue, claiming that the draining of ETH was legal and in accordance to The DAO's rules ("code is law", therefore any execution of the code is always as intended). The Attacker also threatens legal action against any attempt to freeze the drained ETH. If such a case ever made it into a court, it would probably be the most important precedent for the future of decentralised organisations as a whole. Only time will tell where the story goes.

Other criticism


If The DAO has not been taken down by this exploit, it is entirely possible we might've seen a lot of other problems crop up in the future. Here are just some of the possible issues and other ideas that would need to be considered.

Setting a precedent for Ethereum. The way Ethereum handles this exploit may affect how similar future problems would have to be addressed. If they go through with the blacklisting, they might be required by law or asked by the community to do the same in the future for a lot of other things. This can open up a big can of worms. However, if they don't, then they might scare off any other similar projects from using the platform, along with some of their users. Damned if you do, damned if you don't.

Voter apathy. If The DAO would have a large amount of users sitting idly on their tokens rather than voting with their money, the software might have problems reaching the needed quorum to do anything. Apparently in Bitshares, only about 10% of stakeholders participate in voting. Perhaps switching to a Delegated Voting model might help alleviate the issue.

Unexplored legal area. The DAO seems to have aimed to exist in an unexplored legal area. It operates like a security or a venture fund without doing the due diligence. It technically cannot be sued, but people that put money into it might face legal repercussions. All in all, it probably would give any lawyer and government official a headache to try framing it in the existing rule of law.

Lack of KYC. While a lot of people in the crypto community want the government and regulations as far from their projects as possible, some oversight might deter attackers. If every investor in The DAO would be vetted by KYC first, and if only vetted individuals could hold the tokens, anyone attacking The DAO would have to be prepared to get sued and criminally charged for their actions. Right now the best we've got is to try tracing the ETHs they owned back to an exchange and possibly investigate some Ethreum / DAO short calls someone might have set up before the attack (similarly to the idea of "terrorist insider trading").

Rushed deployment. After The DAO has been released, there have been some concerns from people that the code should've been tested and vetted more to iron out any bugs. A code that holds so much money is a gold-filled pinata for any and every hacker that might try to break it 24/7. Some attack vectors have been published before the attack (description and mitigation). Since the contract is vulnerable right after it's released, rushing a release is not wise.

Any bug needs to be fixed immediately. With a smart contract running on a decentralised network, it is vulnerable to exploits all the time. Any new bug that is found needs to be fixed right away, especially if it is described publicly. With more centralised software, you can at least shut everything down until the bug is fixed, but such luxury would be harder to implement in a DAO.

One mistake and your money is gone. While this one applies to most cryptocurrencies, it also bears mentioning - any bug in the code that breaks the smart contract that holds actual money (in this case, ETH) can cost you everything. If you deploy such a piece of code and send money to it, it is gone and you won't be able to get it back.

There are no rollbacks with real coins. While any contract that issues and deals only in its own tokens can be rolled back to any point in time with a patched contract, the matter is not as simple when we're dealing with actual coins (in this case, ETH). As the native coins exist outside of the contract's controls, using such contracts to manage the coins is more dangerous than just dealing in tokens.

Putting all eggs in one basket. A contract holding over 100M USD is a disaster waiting to happen. At the very least some of that money should've been put in some deep cold storage until it is needed. Enter into some legally binding contract with 50 people if you need to to provide some multisig and keep the funds safe. It's like putting all of your coins into a hot wallet - you shouldn't do that.

Paradox of presales. Even if The DAO would function correctly, it might be a hard value proposition, similar to most other ITOs (Initial Token Offering). Unless you are an actual security / fund and building projects that funnel their earnings into the organisation, the projects that benefit The DAO holders rather than Ethereum as a whole might be inferior to the general use case. There is a lot that the Ethereum platform and anything on it could benefit from, but tying them into one smart contract might defeat the purpose. Since many DAOs want to avoid being labelled as a security, we might just get some weird projects in the end.

Relation to other projects


A few people have started comparing this bug to a few other things in the cryptocurrency space. Perhaps it is important to have a look at them and figure out how similar they are.

In the early days of Bitcoin, in mid-2010, someone found a way to create 184'467'440'737.09551616 BTC (almost 10k times more coins than would ever exist) out of thin air in a so called "Value overflow incident". The bug was fixed and the network was rolled back. The bug is similar - use an unexpected way the code works to get access to more tokens than one should be able to. However, this situation is different as it breaks the core functionality of the entire network, rather than a sub-part of it that is not governed by the protocol. Rolling back the network to before the bug was introduced is entirely justified - it is something that shouldn't have happened. With The DAO, the situation is a bit different - the core network functioned as intended, it is the final product that was at fault.

Another incident similar to this was the fall of MtGox allegedly caused by Transaction Malleability, and the attack on JustCoin with Ripple's Partial Payment Flag. In both cases, the software creators did not anticipate an obscure network behaviour that lead to their downfall. In neither cases did the network got rolled back - it functioned as intended, and to my knowledge neither of those companies got bailed out for the bugs in their code. This would probably be the closest analogy.

The decision to bail the contract out and refund the drained ETH might be either seen as the Ethereum Foundation trying to mitigate the damage to the network's reputation, or it might be due to many of the Foundation members lending their credibility to the project itself. One way or the other, I doubt we would see many similar DAOs in the future with such lineup of big name supporters to mitigate any similar damage in the future.

What is also worth noting is that because of Bitcoin's success, a lot of the cryptocurrency projects may "suffer" from an accelerated growth. There have been many incidents in the earlier days of Bitcoin of people losing their money and it wasn't that big of a deal - the coins were worth only so much. However, with networks such as Ethereum being worth a billion dollars less than a year after release, you have similar high profile bugs, but the coins themselves are worth a lot more a lot quicker. Perhaps we should try stalling the gold rush until a project has been vetted by early adopters hammering out all of the kinks and best practices? It's probably not going to happen unfortunately...

Lastly, if the Tau developers want to brag about how their platform is / will be much better than Ethereum since such bugs can't happen there, it is your time to prove yourself - deliver us your implementation of The DAO in a language of your choice so we can pick it apart and see if it breaks.

Conclusions


The DAO has been an interesting ride. It allowed the ETH to double in value and crash back down. A project of this scope if executed correctly would certainly be a game changer for any cryptocurrency network. Unfortunately, as many have made this joke before, it seems The DAO was DOA (dead on arrival). With DAOs, it's perfection or bust.

Spells of Genesis card for The DAO, reading
"Holding so much energy, the Colossus is able to withstand all threats"...

How Bitcoiners see the situation