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Are there ways to reduce the size of the block chain? Or will we get to the point where only large service providers can hold the block chain? I ask because I

Are there ways to reduce the size of the block chain? Or will we get to the point where only large service providers can hold the block chain? I ask because I was maintaining my own wallet for awhile but stopped because the block chain database was getting unwieldy - it would take up to a week to resync if I ever turned my wallet software off for a significant amount of time. You know though... I actually don't care. Bitcoin was an interesting curiosity and useful in some situations (transferring money to people in rural areas of 3rd world countries, for example), but it's slow (up to 15 minutes for the transaction to be approved?), has high fees in its transactions and even higher to convert from/to cash, it's unwieldy... To use it from consumer devices would require someone else managing the wallet, and at that point I'll instead just use cash or a credit card.

wmf 12y ago
SPV or ultimate blockchain compression can reduce storage requirements significantly.
alvarosm 12y ago
Blockchain pruning would drastically reduce the size and it could be implemented relatively easily but it's not on the standard client(or any other afaik). You only need to keep unspent transactions (after you're confident a block reorganisation wouldn't go as deep as the block where you're pruning old tx).
dollaaron 12y ago
I believe there are proposals to allow pruning the blockchain, but I'm not 100% sure on the details. To guarantee a transaction goes through you have to wait for it to be confirmed, but most transactions really aren't that important/high risk, so beyond checking that the address does actually have the money, it's instantaneous. Many payment processors (I know Bitpay has this option) actually take the 0 confirmation transaction risk, allowing customers to pay instantly. Transaction fees are not high, with a typical fee of .0001 bitcoin (3 cents), which is small compared to credit card fees. While work needs to be done converting to/from cash, actually using bitcoin (that you already have) to buy things is a better experience than using credit cards. You simply grab your phone, scan the QR code, and hit send. This is much better than entering your credit card for the thousandth time on another website, or being redirected to paypal, entering your password, and choosing your preferred payment option for the thousandth time (stop asking me to use Paypal Credit!). Using an Android wallet such as Mycelium, or a desktop wallet like Electrum doesn't require you to download the entire blockchain, and although that comes at the cost of some trust, I personally don't find that problematic. Basically, bitcoin has some problems, but I think some of your criticisms are no longer applicable to most everyday usage of it.
- CPLX 12y ago
  > actually using bitcoin (that you already have) to buy things is a better experience than using credit cards It's just not. It's not easier than swiping a magnetic strip and signing something, or typing in sixteen digits (or using autofill or the site's previously saved CC info) and pressing buy. It's not good that I can't demand a return or have recourse in the event of fraud. And it's not a benefit that with bitcoin I have to spend the money first (to buy bitcoin) and wonder if it will hold its value, versus just buying stuff when I feel like it on credit and covering the transaction within 30 days at no interest cost. I know there are a lot of people who really want your above quoted statement to be true. But, for now and the forseeable future, it isn't.
  - dollaaron 12y ago
    > It's just not. It's not easier than swiping a magnetic strip and signing something, or typing in sixteen digits (or using autofill or the site's previously saved CC info) and pressing buy. It's much easier to take your phone, open an app, and scan a QR code, than to take out your credit card, transcribe a 16 digit number, check the expiration date, and enter the CSC (or is it CVC?). Sure, for websites where your information is already saved, or if you leave all your credit card information saved in the browser, then this isn't easier, but they're still pretty comparable in my opinion. Even if it was slightly more work (which I personally disagree with), I would find that worth not having my credit card information saved by who knows how many third parties. > It's not good that I can't demand a return or have recourse in the event of fraud. I've never had to go to my credit card company for a refund, since most places I buy from will take refunds with a receipt or proof of purchase (and if they don't, why would I buy from them?). Fraudulent purchases are another issue, but the risk of fraud is lower with bitcoin versus credit cards (no single number that allows access to all funds, a properly secured wallet is impossible to steal, although I know wallet security is still not the easiest thing to have). > And it's not a benefit that with bitcoin I have to spend the money first (to buy bitcoin) and wonder if it will hold its value, versus just buying stuff when I feel like it on credit and covering the transaction within 30 days at no interest cost. This is a very real problem, and what I think will truly determine whether bitcoin gains anything near a large following.
padelt 12y ago
There is the concept of pruning in the original paper[1] which basically removes all fully-spent transaction trails. That does not yield a reasonable upper bound on the size though[2]. Beyond pruning, it seems you need to trust another network component (external wallet, server). [1] https://en.bitcoin.it/wiki/Scalability#Storage https://en.bitcoin.it/wiki/Scalability#Storage [2] http://bitcoin.stackexchange.com/questions/4650/upper-limit-on-the-blockchain-file-size-with-pruning http://bitcoin.stackexchange.com/questions/4650/upper-limit-...
richcollins 12y ago
There is an iOS wallet that connects directly to the network that downloads the necessary info in seconds: https://itunes.apple.com/us/app/breadwallet-bitcoin-wallet/id885251393?mt=8 https://itunes.apple.com/us/app/breadwallet-bitcoin-wallet/i...
- EC1 12y ago
  Wouldn't this be really power draining? Having to sync and download constantly.
- deweller 12y ago
  This uses Simplfied Payment Verification (SPV). SPV helps with some scalability issues, but doesn't solve them all. From http://bitcoin.stackexchange.com/questions/4649/what-is-an-spv-client http://bitcoin.stackexchange.com/questions/4649/what-is-an-s...: > SPV: A Bitcoin implementation that does not verify everything, but instead relies on either connecting to a trusted node, or puts its faith in high difficulty as a proxy for proof of validity. BitCoinJ is an implementation of this mode. See also: http://bitcoin.stackexchange.com/questions/11054/understanding-spv-simple-payment-verification http://bitcoin.stackexchange.com/questions/11054/understandi...
chatmasta 12y ago
This is an important question since the focus of the article's speculation is on the Internet of things. Obviously embedded devices are not going to be lugging around gigabytes of blockchain any time soon. Even with pruning you're not going to get the size down to a realistic number for devices with little to no hard drive capacity. I imagine in any IoT scenario, a fleet of sensors talks to a trusted central hub. If Bitcoin is involved then the hub could run the wallet and the sensors could delegate transactions to it.
puranjay 12y ago
I'm in India and I can't even buy it easily. Paypal hates it, as does India's Reserve Bank. Too much effort for too little reward. Right now, the only thing I'd actually want to buy with BTC is illegal stuff off the darknet. There is virtually nothing else I need that bad that normal cash can't do.
- 666_howitzer 12y ago
  I'm from Bangalore, I have used localbitcoins quite a few times actually, all the trades went smoothly. The only issue I have with LBTC is you have pay a small premium compared to other exchanges for added convenience. https://localbitcoins.com/ https://localbitcoins.com/
- jafaku 12y ago
  > Paypal hates it, as does India's Reserve Bank. I can't believe this doesn't immediately make you think that maybe, just maybe there is something good about Bitcoin. Are you 0K with the central bank stealing wealth from you and your family through the debasing of your currency? Are you 0K with working your ass off so that bankers and other powerful people can live a life of wealth and pleasure? How can you take advise from such people? "Bitcoin is bad, don't use it! It's a drug currency... very shady... also, terrorism!" That is basically what every central bank said to the people in their country.
- anilgulecha 12y ago
  unocoin seems to make it quite easy to buy /sell in India.
mrb 12y ago
Yes there is a solution. The reason it took you days to resync was because you ran the reference implementation, Bitcoin Core, which is meant for "full nodes" running 24/7. Simple users like you should instead run "thin client" or SPV wallets (Simple Payment Verification) which do not need to store the whole block chain, allowing your wallet to resync pretty much instantly. For a list of SPV wallets see https://bitcoin.org/en/choose-your-wallet https://bitcoin.org/en/choose-your-wallet and look for those labelled "simplified validation". You also very likely ran into the problem that older versions of Bitcoin Core were slow to download blocks. For example version 0.10.0 released in February 2015 introduces parallel block download, which makes resyncing faster. Numerous other optimizations were made over the last 12-24 months (eg. better detection of stalled downloads). From your description it sounds like you were running a significantly older version of Bitcoin Core, so you were missing out on all these optimizations. I would like to point out that despite the block chain growing continuously, we are still very far from the point where only large service providers can hold the block chain. The average block size is currently ~400 kB (https://blockchain.info/charts/avg-block-size?showDataPoints=false&timespan=&show_header=true&daysAverageString=7&scale=0&address= https://blockchain.info/charts/avg-block-size?showDataPoints...), this means the block chain grows by ~20 GB every year. This is only 1% the size of an average desktop hard drive (2 TB), and would take only 4.5 hours to download (once a year, mind you) assuming a steady common residential Internet download speed of 10 Mbit/s. Heck, a dedicated computer on a common residential Internet connection could still run as a full node and handle an average block size 100x larger that today (~40 MB per block, 2 TB growth per year = 0.5 Mbit/s continuous download). I would hardly describe something an enthusiast can do as a thing that "only large service providers can do". And keep in mind by the time 100x growths happens, CPUs/HDDs/Internet speeds will be much faster than today. Bitcoin's scalability has already been benchmarked pretty well: https://en.bitcoin.it/wiki/Scalability https://en.bitcoin.it/wiki/Scalability - no immediate bottlenecks are in sight. "high fees in its transactions" Fees are optional, and typically 0.0001 BTC (3 cents). "up to 15 minutes for the transaction to be approved" No, transactions are typically "received" instantly within seconds, and take 10-60 minutes on average to "settle" (be confirmed by 1 to 6 blocks). This is a lot faster than credit cards or ACH which both take 24h (or more if this is a weekend) to be received (ie. dollars available in the recipient's account), or bank wires which take days (or end-of-business-day if your are lucky).
jafaku 12y ago
"Hi everyone, I just heard about Bitcoin... And I'm here to fix it"
IkmoIkmo 12y ago
Yes, it's called pruning, it's in development and not finished. The basic idea is that bitcoins are actually units of money that are in your wallet. Rather bitcoin works by chaining transactions (put into blocks, hence the blockchain). Thus if you give me $1, I don't have $1, I actually have a record that you gave me $1 so that must mean I have $1 to spend. That's the simplistic idea. That is the reason why instead of storing account numbers with money numbers in them, bitcoin stores transactions. By now it's probably obvious to you that the vast majority of those transactions don't need to be stored. If I give you $1 and you give it back, repeat 1 million times, we end up with exactly the same amount of money. And all but the last few transactions can be reasonable deleted. (pruning) As for syncing, syncing up a wallet is much, much faster now that it's headers first. But most users never sync, they either use 3rd party wallets like Coinbase, or they use wallet software that plugs into various nodes and APIs, so that no blockchain has to be present on-disk. The blockchain is really stored mostly by nodes, dedicated servers, businesses, a few enthusiasts. That doesn't mean someone else manages the wallet by the way, like you mentioned for 'consumer devices', it just means that someone else manages the node. But the node doesn't control your money, your private keys do, and those are just a few bytes of storage. And as there are thousands of nodes and many APIs, trust of nodes isn't any different as when running your own node (which gets and sends data to other nodes, requiring the exact same amount of trust which is zero when it comes to controlling your money). As for transaction fees being expensive, they're extremely cheap? Pennies to send thousands or millions, and as it's an open protocol anyone can build free centralized payment networks on top of it, like Changetip. Conversion with other currencies is also cheaper than most fiat conversions (e.g. dollar to euro), and in fact some companies already offer it for free (e.g. bitcoin/usd is completely free and pretty much instant with Circle, founded by Jeremy Allaire who founded Coldfusion). The 15minute thing might be a deal-breaker for some. There are lots of solutions though that can remove that timer, built on top of bitcoin. Sidechains, treechains, payment channels etc. Anyway time will tell if these things work well but there don't seem to be any dealbreakers yet on the horizon.
Procrastes 12y ago
There are a couple of good options for working with truncated blockchains to a checkpoint without reducing the security of the blockchain. Likely one or the other with settle out as the common practice, and the blockchain growth problem will be solved. Power consumption, on the other hand, may not be solvable even in theory, and it also seems likely to drive mining to just large service providers. The current pools aren't a solution in this case because the startup cost to even participate meaningfully will grow too large. Maybe this could be solvable with a different proof mechanism. A few have been suggested and tried (PPC etc.), but I don't think it's solvable for BTC as it's currently defined. I'm happy to be proven wrong.
deleted 12y ago
[deleted]
imaginenore 12y ago
What are you talking about? Blockchain is now 30GB. A 4TB drive costs around $120. So it literally costs you 90 cents to store that data. If 30GB bothers you, use MultiBit or Electrum.

wmf 12y ago

SPV or ultimate blockchain compression can reduce storage requirements significantly.

alvarosm 12y ago

Blockchain pruning would drastically reduce the size and it could be implemented relatively easily but it's not on the standard client(or any other afaik). You only need to keep unspent transactions (after you're confident a block reorganisation wouldn't go as deep as the block where you're pruning old tx).

dollaaron 12y ago

I believe there are proposals to allow pruning the blockchain, but I'm not 100% sure on the details. To guarantee a transaction goes through you have to wait for it to be confirmed, but most transactions really aren't that important/high risk, so beyond checking that the address does actually have the money, it's instantaneous. Many payment processors (I know Bitpay has this option) actually take the 0 confirmation transaction risk, allowing customers to pay instantly. Transaction fees are not high, with a typical fee of .0001 bitcoin (3 cents), which is small compared to credit card fees. While work needs to be done converting to/from cash, actually using bitcoin (that you already have) to buy things is a better experience than using credit cards. You simply grab your phone, scan the QR code, and hit send. This is much better than entering your credit card for the thousandth time on another website, or being redirected to paypal, entering your password, and choosing your preferred payment option for the thousandth time (stop asking me to use Paypal Credit!). Using an Android wallet such as Mycelium, or a desktop wallet like Electrum doesn't require you to download the entire blockchain, and although that comes at the cost of some trust, I personally don't find that problematic. Basically, bitcoin has some problems, but I think some of your criticisms are no longer applicable to most everyday usage of it.

CPLX 12y ago
> actually using bitcoin (that you already have) to buy things is a better experience than using credit cards It's just not. It's not easier than swiping a magnetic strip and signing something, or typing in sixteen digits (or using autofill or the site's previously saved CC info) and pressing buy. It's not good that I can't demand a return or have recourse in the event of fraud. And it's not a benefit that with bitcoin I have to spend the money first (to buy bitcoin) and wonder if it will hold its value, versus just buying stuff when I feel like it on credit and covering the transaction within 30 days at no interest cost. I know there are a lot of people who really want your above quoted statement to be true. But, for now and the forseeable future, it isn't.
- dollaaron 12y ago
  > It's just not. It's not easier than swiping a magnetic strip and signing something, or typing in sixteen digits (or using autofill or the site's previously saved CC info) and pressing buy. It's much easier to take your phone, open an app, and scan a QR code, than to take out your credit card, transcribe a 16 digit number, check the expiration date, and enter the CSC (or is it CVC?). Sure, for websites where your information is already saved, or if you leave all your credit card information saved in the browser, then this isn't easier, but they're still pretty comparable in my opinion. Even if it was slightly more work (which I personally disagree with), I would find that worth not having my credit card information saved by who knows how many third parties. > It's not good that I can't demand a return or have recourse in the event of fraud. I've never had to go to my credit card company for a refund, since most places I buy from will take refunds with a receipt or proof of purchase (and if they don't, why would I buy from them?). Fraudulent purchases are another issue, but the risk of fraud is lower with bitcoin versus credit cards (no single number that allows access to all funds, a properly secured wallet is impossible to steal, although I know wallet security is still not the easiest thing to have). > And it's not a benefit that with bitcoin I have to spend the money first (to buy bitcoin) and wonder if it will hold its value, versus just buying stuff when I feel like it on credit and covering the transaction within 30 days at no interest cost. This is a very real problem, and what I think will truly determine whether bitcoin gains anything near a large following.

padelt 12y ago

There is the concept of pruning in the original paper[1] which basically removes all fully-spent transaction trails. That does not yield a reasonable upper bound on the size though[2]. Beyond pruning, it seems you need to trust another network component (external wallet, server). [1] https://en.bitcoin.it/wiki/Scalability#Storage https://en.bitcoin.it/wiki/Scalability#Storage [2] http://bitcoin.stackexchange.com/questions/4650/upper-limit-on-the-blockchain-file-size-with-pruning http://bitcoin.stackexchange.com/questions/4650/upper-limit-...

richcollins 12y ago

There is an iOS wallet that connects directly to the network that downloads the necessary info in seconds: https://itunes.apple.com/us/app/breadwallet-bitcoin-wallet/id885251393?mt=8 https://itunes.apple.com/us/app/breadwallet-bitcoin-wallet/i...

EC1 12y ago
Wouldn't this be really power draining? Having to sync and download constantly.
deweller 12y ago
This uses Simplfied Payment Verification (SPV). SPV helps with some scalability issues, but doesn't solve them all. From http://bitcoin.stackexchange.com/questions/4649/what-is-an-spv-client http://bitcoin.stackexchange.com/questions/4649/what-is-an-s...: > SPV: A Bitcoin implementation that does not verify everything, but instead relies on either connecting to a trusted node, or puts its faith in high difficulty as a proxy for proof of validity. BitCoinJ is an implementation of this mode. See also: http://bitcoin.stackexchange.com/questions/11054/understanding-spv-simple-payment-verification http://bitcoin.stackexchange.com/questions/11054/understandi...

chatmasta 12y ago

This is an important question since the focus of the article's speculation is on the Internet of things. Obviously embedded devices are not going to be lugging around gigabytes of blockchain any time soon. Even with pruning you're not going to get the size down to a realistic number for devices with little to no hard drive capacity. I imagine in any IoT scenario, a fleet of sensors talks to a trusted central hub. If Bitcoin is involved then the hub could run the wallet and the sensors could delegate transactions to it.

puranjay 12y ago

I'm in India and I can't even buy it easily. Paypal hates it, as does India's Reserve Bank. Too much effort for too little reward. Right now, the only thing I'd actually want to buy with BTC is illegal stuff off the darknet. There is virtually nothing else I need that bad that normal cash can't do.

666_howitzer 12y ago
I'm from Bangalore, I have used localbitcoins quite a few times actually, all the trades went smoothly. The only issue I have with LBTC is you have pay a small premium compared to other exchanges for added convenience. https://localbitcoins.com/ https://localbitcoins.com/
jafaku 12y ago
> Paypal hates it, as does India's Reserve Bank. I can't believe this doesn't immediately make you think that maybe, just maybe there is something good about Bitcoin. Are you 0K with the central bank stealing wealth from you and your family through the debasing of your currency? Are you 0K with working your ass off so that bankers and other powerful people can live a life of wealth and pleasure? How can you take advise from such people? "Bitcoin is bad, don't use it! It's a drug currency... very shady... also, terrorism!" That is basically what every central bank said to the people in their country.
anilgulecha 12y ago
unocoin seems to make it quite easy to buy /sell in India.

mrb 12y ago

Yes there is a solution. The reason it took you days to resync was because you ran the reference implementation, Bitcoin Core, which is meant for "full nodes" running 24/7. Simple users like you should instead run "thin client" or SPV wallets (Simple Payment Verification) which do not need to store the whole block chain, allowing your wallet to resync pretty much instantly. For a list of SPV wallets see https://bitcoin.org/en/choose-your-wallet https://bitcoin.org/en/choose-your-wallet and look for those labelled "simplified validation". You also very likely ran into the problem that older versions of Bitcoin Core were slow to download blocks. For example version 0.10.0 released in February 2015 introduces parallel block download, which makes resyncing faster. Numerous other optimizations were made over the last 12-24 months (eg. better detection of stalled downloads). From your description it sounds like you were running a significantly older version of Bitcoin Core, so you were missing out on all these optimizations. I would like to point out that despite the block chain growing continuously, we are still very far from the point where only large service providers can hold the block chain. The average block size is currently ~400 kB (https://blockchain.info/charts/avg-block-size?showDataPoints=false&timespan=&show_header=true&daysAverageString=7&scale=0&address= https://blockchain.info/charts/avg-block-size?showDataPoints...), this means the block chain grows by ~20 GB every year. This is only 1% the size of an average desktop hard drive (2 TB), and would take only 4.5 hours to download (once a year, mind you) assuming a steady common residential Internet download speed of 10 Mbit/s. Heck, a dedicated computer on a common residential Internet connection could still run as a full node and handle an average block size 100x larger that today (~40 MB per block, 2 TB growth per year = 0.5 Mbit/s continuous download). I would hardly describe something an enthusiast can do as a thing that "only large service providers can do". And keep in mind by the time 100x growths happens, CPUs/HDDs/Internet speeds will be much faster than today. Bitcoin's scalability has already been benchmarked pretty well: https://en.bitcoin.it/wiki/Scalability https://en.bitcoin.it/wiki/Scalability - no immediate bottlenecks are in sight. "high fees in its transactions" Fees are optional, and typically 0.0001 BTC (3 cents). "up to 15 minutes for the transaction to be approved" No, transactions are typically "received" instantly within seconds, and take 10-60 minutes on average to "settle" (be confirmed by 1 to 6 blocks). This is a lot faster than credit cards or ACH which both take 24h (or more if this is a weekend) to be received (ie. dollars available in the recipient's account), or bank wires which take days (or end-of-business-day if your are lucky).

jafaku 12y ago

"Hi everyone, I just heard about Bitcoin... And I'm here to fix it"

IkmoIkmo 12y ago

Yes, it's called pruning, it's in development and not finished. The basic idea is that bitcoins are actually units of money that are in your wallet. Rather bitcoin works by chaining transactions (put into blocks, hence the blockchain). Thus if you give me $1, I don't have $1, I actually have a record that you gave me $1 so that must mean I have $1 to spend. That's the simplistic idea. That is the reason why instead of storing account numbers with money numbers in them, bitcoin stores transactions. By now it's probably obvious to you that the vast majority of those transactions don't need to be stored. If I give you $1 and you give it back, repeat 1 million times, we end up with exactly the same amount of money. And all but the last few transactions can be reasonable deleted. (pruning) As for syncing, syncing up a wallet is much, much faster now that it's headers first. But most users never sync, they either use 3rd party wallets like Coinbase, or they use wallet software that plugs into various nodes and APIs, so that no blockchain has to be present on-disk. The blockchain is really stored mostly by nodes, dedicated servers, businesses, a few enthusiasts. That doesn't mean someone else manages the wallet by the way, like you mentioned for 'consumer devices', it just means that someone else manages the node. But the node doesn't control your money, your private keys do, and those are just a few bytes of storage. And as there are thousands of nodes and many APIs, trust of nodes isn't any different as when running your own node (which gets and sends data to other nodes, requiring the exact same amount of trust which is zero when it comes to controlling your money). As for transaction fees being expensive, they're extremely cheap? Pennies to send thousands or millions, and as it's an open protocol anyone can build free centralized payment networks on top of it, like Changetip. Conversion with other currencies is also cheaper than most fiat conversions (e.g. dollar to euro), and in fact some companies already offer it for free (e.g. bitcoin/usd is completely free and pretty much instant with Circle, founded by Jeremy Allaire who founded Coldfusion). The 15minute thing might be a deal-breaker for some. There are lots of solutions though that can remove that timer, built on top of bitcoin. Sidechains, treechains, payment channels etc. Anyway time will tell if these things work well but there don't seem to be any dealbreakers yet on the horizon.

Procrastes 12y ago

There are a couple of good options for working with truncated blockchains to a checkpoint without reducing the security of the blockchain. Likely one or the other with settle out as the common practice, and the blockchain growth problem will be solved. Power consumption, on the other hand, may not be solvable even in theory, and it also seems likely to drive mining to just large service providers. The current pools aren't a solution in this case because the startup cost to even participate meaningfully will grow too large. Maybe this could be solvable with a different proof mechanism. A few have been suggested and tried (PPC etc.), but I don't think it's solvable for BTC as it's currently defined. I'm happy to be proven wrong.

deleted 12y ago

[deleted]

imaginenore 12y ago

What are you talking about? Blockchain is now 30GB. A 4TB drive costs around $120. So it literally costs you 90 cents to store that data. If 30GB bothers you, use MultiBit or Electrum.