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Facebook Libra Is Architecturally Unsound

stephendiehl.com

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Re: Facebook Libra Is Architecturally Unsound

#161

Post by marcosdumay »

matthewdgreen wrote: post #148
nokcha wrote: post #143

Earlier quoted context omitted.

>"The possibility that a Libra node run by Mastercard or Andressen Horrowitz would suddenly start running malicious code is such a bizarre scenario to plan for and is better solved by simply enforcing protocol integrity and through non-technical (i.e. legal) means." In regards to that, I don't think it's any more bizarre than a SCADA system in an Iranian nuclear enrichment plant suddenly running malicious code. Cyber…

To the best of my knowledge, no deployed banking system relies on immutable ledgers. They all rely on detection and revision of ledgers. Libra has chosen to do something fundamentally different, and the author is asking why.

The ledgers are officially immutable. Revisions are done as separate entries from the errors and both are expected to stay registered there.

Re: Facebook Libra Is Architecturally Unsound

#162

Post by acdha »

matthewdgreen wrote: post #157
acdha wrote: post #156

Earlier quoted context omitted.

> The purpose here is simply to evade and arbitrage different regulatory regimes. The plan is to build a ledger that no single party (or coalition of parties in a single legal jurisdiction) has the capacity to edit or alter, and to make such alterations so technically challenging that it's beyond the capacity of any single court or legislature to do so. If they respond to a legal demand saying “Our software won't let…

That is precisely what Libra is banking on. We'll see if they're right.

You certainly aren't wrong to describe it as potentially horrifying.

Re: Facebook Libra Is Architecturally Unsound

#163

Post by rudolph9 »

forgotmyhnacc wrote: post #152

I'm confused about this article. I've read it, and it's skeptical of libra (which is fine) but makes handwavy and non concrete arguments about it's soundness. Can anyone tell me why it's so popular, besides just bashing Facebook?

Because, facebook. He make a good point about privacy but even that was kinda handwavy.

Re: Facebook Libra Is Architecturally Unsound

#164

Post by wongarsu »

scott_s wrote: post #155
wongarsu wrote: post #110

Earlier quoted context omitted.

If an ebay seller delivers me a faulty product I can sue them for not delivering what I payed for and when I win the court orders them to pay the money back (plus my expenses). If they don't pay I can go after their assets. It's basically the same how a business would recover money from a bad supplier. With small claims court it's even somewhat efficient for small sums, but of course still orders of magnitude more wo…

That's an enormous burden. If we require lawsuits to enforce even minor cases of consumer protection, I argue that there is effectively no actual consumer protection.

The law not working for "minor cases" (which includes cases over hundreds of dollars) is exactly the failing of the justice system I mentioned. This isn't universal, in many places you can get theft of a Mars bar or possession of tiny amounts of drugs prosecuted very effectively, all cases much more minor than the typical credit card dispute.

Re: Facebook Libra Is Architecturally Unsound

#165

Post by amluto »

I have only studied Move by reading the whitepaper, but there's a gaping architectural hole that I found in five minutes:

    public withdraw_from_sender(amount:u64): Coin {
       let transaction_sender_address: address = GetTxnSenderAddress();
       ...
    }
Checking the global txn sender address is not a sound way to authorize a transaction in a smart contract language. Consider that a buggy or malicious function in a different smart contract could call withdraw(). Linear type theory might prevent the resulting stolen coins from being duplicated, but they're still stolen.

I don't know if there is a clean theoretically sound way to do this, but here's an idea based on linear types:

The main function in a transaction is given a Sender object as one of its arguments. The Sender has a method that generates an assertion (an object) that the transaction intends to perform a specific action, e.g. withdraw 10 coins of type A. The withdraw() function takes an assertion as a parameter and calls a method that consumes the assertion before withdrawing the coins.

Re: Facebook Libra Is Architecturally Unsound

#166

Post by kragen »

rossdavidh wrote: post #116
pron wrote: post #86

Earlier quoted context omitted.

I think this question is best answered by economists, and I'm certainly not one. But blockchain does seem to interfere with some of the best regulatory defenses against economic disasters.

Blockchain gives the impression that the primary threat it is designed to defend against, is a government deciding (like Germany between world wars) to inflate their currency for whatever reason. So, not surprisingly, in order to defend a currency against being decreased in value by a central authority, it is vulnerable to all of the threats that a central monetary authority might help you with. Which of these threat…

Right, here in Argentina our currency has lost more than half its value this year, and the US dollar has lost 96% of its value since the end of the gold standard in 1973. I carry a Zimbabwe 100 trillion dollar bill in my wallet to remind people what real hyperinflation is.

I don't think that's the main threat Bitcoin is designed to defend against, though; I think there's a whole spectrum of confiscation threats, ranging from thieves tunneling into bank vaults (I know a woman here who lost her savings that way), to immigration authorities confiscating jewelry, to pirates, to trumped-up "money laundering" charges. And of course if we're mentioning Germany and World Wars, we must not forget the confiscation of Holocaust victims' entire possessions, including jewelry and fillings after the gas chambers. Bitcoin can't make genocide impossible but maybe at least it can make it unprofitable.

Re: Facebook Libra Is Architecturally Unsound

#167

Post by gerikson »

robbya wrote: post #92

What's the profit potential for Facebook here, especially above using an existing cryptocurrency for payments on their platforms? Having low friction payments on Facebook makes sense, it build value into the platform and Facebook can capture some of that. But can't they do that with an existing cryptocurrency? It doesn't seem like Facebook will maintain full control of the currency due to the consensus algorithm. The…

> What's the profit potential for Facebook here

In a world where "everyone" uses Libra, they need a FB account to access their wallet, and FB will see every consumer decision at its most valuable - the point of exchanging money for goods and services. This is immensely valuable for an ad company.

Re: Facebook Libra Is Architecturally Unsound

#168

Post by Jeff_Brown »

gerikson wrote: post #160
Jeff_Brown wrote: post #69

Earlier quoted context omitted.

I think it's weird how family gets invoked to change the moral gravity of an issue. It suggests orphaned children, for instance, should care less about humanity.

How does being an orphan make one care less about humanity? Personally, I want orphans (as defined as minors with no living parents) to be well-cared for regardless, either by relatives or by an outside agency ("orphanage" or foster home).

Absolutely, that's my point. We should care about people, period. Whether one has a family should be irrelevant to the question of how to engineer a society.

Re: Facebook Libra Is Architecturally Unsound

#170

Post by gerikson »

z3t4 wrote: post #85

When you make a oversea money transaction the banks take up to 20%. For every electronic transaction a bunch of middle-men takes a percentage. Maybe there need to be a payout for those that keep the system running? Like in Bitcoin mining ... But the thing is, transactions can be highly automated, with almost zero marginal cost (the cost of making yet a transaction when you already process millions per second). So the…

> When you make a oversea money transaction the banks take up to 20%.

You need to comparison-shop the price of remittance: https://www.saveonsend.com/blog/welcome/#more-1

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