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Maybe Blockchain Really Does Have Magical Powers

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Re: Maybe Blockchain Really Does Have Magical Powers

#71

Post by runeks »

zby wrote: post #69
lhl wrote: post #3

I'm all for deflating blockchain hype, but I found the overall tone of the article pretty disagreeable, and more importantly, wholly missing the point. "In other words, the only thing previously stopping the standardization of reconciliation processes was the unwillingness of financial institutions to collaborate." No, actually, the one thing the blockchain provides, which was literally unsolved before pre-Nakamoto,…

The trustlesness comes with a heavy price of Proof of Work with its wastefulness, complexity and vulnerability to various attacks. I can understand why financial institutions don't want that part.

It shouldn't be necessary either. The proof-of-work is only necessary to avoid a central party wrt. which blockchain is the "right one". Financial institutions are working together with each other, they can easily just agree on which blockchain to follow. But without proof-of-work, the blockchain is just a database with atomic updates. I don't see why they would need a blockchain for that.

Ripping Bitcoin in two gives you two fairly uninteresting things: 1) hash-cash and 2) a database full of public keys/signatures. Only combining the two gives you something interesting: negotiable/fungible hash cash (hash cash that can be transferred from person to person via a distributed database).

Re: Maybe Blockchain Really Does Have Magical Powers

#72

Post by Avalaxy »

heliumcraft wrote: post #67
Avalaxy wrote: post #63

We keep seeing a lot of examples of how Machine Learning can really innovate and reinvent all sorts of processes (i.e. the vegetable sorting we saw on HN yesterday), but when it comes to blockchains, it seems that it's mostly talk about how it could potentially change everything, but so far I haven't seen many very useful examples that couldn't have been done without using a blockchain (the whole blockchain thing oft…

http://dapps.ethercasts.com/

Are any of these dapps really in use and making a difference? It seems to me that the listed dapps are mostly technical proof of concepts. For example: a decentralized actuary sounds great, but I find it highly unlikely that the industry is really accepting it. Same goes for flight insurance and option exchanges.

Re: Maybe Blockchain Really Does Have Magical Powers

#73

Post by semi-extrinsic »

wmf wrote: post #49
semi-extrinsic wrote: post #30

Earlier quoted context omitted.

> The problem that Bitcoin solves and private blockchains do not is called the Byzantine generals problem which did not have a known solution until Bitcoin came along. I'm not an expert in any way, but the Wikipedia page for Byzantine Fault Tolerance suggests a solution to this problem was known as early as 2001, used in the Boeing 777 avionics software. See abstract of the paper below. That significantly predates Bi…

There were known solutions given a fixed set of generals. Nakamoto consensus handles the case of an unknown number of anonymous generals (miners) who may come and go when they please.

Out of curiosity: were there known solutions for an arbitrarily large number of fixed generals? Could a similar solution as with Nakamoto consensus be obtained by having a huge, fixed number of generals, setting some as occupied and using live inputs for those, and then using an alternating series of yes/no votes for the unoccupied generals? (Maybe you'd have trouble with off-by-one errors in the alternating series, but you could ad-hoc fix that.)

Come to think of it, why does the variable number of generals make a difference? When you are making a single decision, is that decision not an atomic operation such that the number of generals influencing it is fixed? Otherwise, wouldn't necessarily the outcome of the vote be (marginally) affected by the order in which you evaluate the votes cast? (That seems like a very bad property for a consensus algorithm to have.)

Re: Maybe Blockchain Really Does Have Magical Powers

#74

Post by dgreensp »

runeks wrote: post #71
zby wrote: post #69

Earlier quoted context omitted.

The trustlesness comes with a heavy price of Proof of Work with its wastefulness, complexity and vulnerability to various attacks. I can understand why financial institutions don't want that part.

It shouldn't be necessary either. The proof-of-work is only necessary to avoid a central party wrt. which blockchain is the "right one". Financial institutions are working together with each other, they can easily just agree on which blockchain to follow. But without proof-of-work, the blockchain is just a database with atomic updates. I don't see why they would need a blockchain for that. Ripping Bitcoin in two give…

I think by "blockchain" they mean hashed blocks that include the hash of the previous block and can be synced; basically git.

Re: Maybe Blockchain Really Does Have Magical Powers

#75

Post by Ar-Curunir »

wmf wrote: post #70
brians wrote: post #57

Earlier quoted context omitted.

But you still need them in a Blockchain world, and still need to trust them.

Or you could convince some other banks to vouch for your transactions if you vouch for theirs and then get rid of the middlemen.

Isn't this similar to the cryptocurrency Stellar

Re: Maybe Blockchain Really Does Have Magical Powers

#76

Post by bendbro »

runeks wrote: post #71
zby wrote: post #69

Earlier quoted context omitted.

The trustlesness comes with a heavy price of Proof of Work with its wastefulness, complexity and vulnerability to various attacks. I can understand why financial institutions don't want that part.

It shouldn't be necessary either. The proof-of-work is only necessary to avoid a central party wrt. which blockchain is the "right one". Financial institutions are working together with each other, they can easily just agree on which blockchain to follow. But without proof-of-work, the blockchain is just a database with atomic updates. I don't see why they would need a blockchain for that. Ripping Bitcoin in two give…

I had this feeling when I was discussing it here.

https://news.ycombinator.com/item?id=12044767

Re: Maybe Blockchain Really Does Have Magical Powers

#77

Post by bachback »

gbarc888 wrote: post #64
jhallenworld wrote: post #48

The example clarifies my feeling about blockchain: How would the example provided (avoiding the clearing house) work without the banks accepting something like a mining-backed crypto-currency like bitcoin? With bitcoins, there is no possibility for dispute: bank A gives bank B the money during the transfer. Any other scheme involves a promise (a legal contract), so you will not know for sure that bank A really had th…

In scenario (4), they're bank-backed crypto-currencies. Banks are trying to build their own settlement coins: http://www.coindesk.com/utilities-settlement-all-about-banks...

other approach is issued ColoredCoin by banks - Lykke.com does this. then you get pricing of assets. fiat money are already "settlement coins", the question is about liquidity, risk and openness.

Re: Maybe Blockchain Really Does Have Magical Powers

#78

Post by yummyfajitas »

wmf wrote: post #70
brians wrote: post #57

Earlier quoted context omitted.

But you still need them in a Blockchain world, and still need to trust them.

Or you could convince some other banks to vouch for your transactions if you vouch for theirs and then get rid of the middlemen.

No, because many of the middle men are there because you don't trust yourself.

Imagine you wanted to build a Hubspot/Triggermail/Vero type system, where you send emails to users when certain events are triggered.

Now suppose you use Sendgrid or Amazon to actually transmit your mail. You are unlikely to give very many developers actual sendgrid keys or access to call sendgrid. Most developers will call an internal API to send mail. This internal API will then perform a bunch of sanity checks - duplicate detection, rate limits, dirty word filters, etc.

Can you "cut out the middle man" by letting each internal service have their own internet connected SMTP server, and stop paying sendgrid and fire whoever builds the internal API? That would be pretty silly.

Similarly, a bank can't really get rid of the risk checks, money laundering checks, data normalization checks, etc.

Re: Maybe Blockchain Really Does Have Magical Powers

#79

Post by kordless »

Ar-Curunir wrote: post #75
wmf wrote: post #70

Earlier quoted context omitted.

Or you could convince some other banks to vouch for your transactions if you vouch for theirs and then get rid of the middlemen.

Isn't this similar to the cryptocurrency Stellar

You can use Stellar to build a gateway to another store of value, including bitcoin, dollar, mpesa, rai stone or, my favorite analogy, barn doors you have sitting in a shed somewhere.

Re: Maybe Blockchain Really Does Have Magical Powers

#80

Post by wmf »

semi-extrinsic wrote: post #73
wmf wrote: post #49

Earlier quoted context omitted.

There were known solutions given a fixed set of generals. Nakamoto consensus handles the case of an unknown number of anonymous generals (miners) who may come and go when they please.

Out of curiosity: were there known solutions for an arbitrarily large number of fixed generals? Could a similar solution as with Nakamoto consensus be obtained by having a huge, fixed number of generals, setting some as occupied and using live inputs for those, and then using an alternating series of yes/no votes for the unoccupied generals? (Maybe you'd have trouble with off-by-one errors in the alternating series,…

I assume protocols like Paxos can work with any odd number of generals. Since the generals are anonymous, consider a Sybil attack. If there are N total generals, what's to prevent me from claiming that I am all N generals? If there are N total generals but M entities try to each spam the system with fake generals, how does the system decide?
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