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[SapphireSpire]

nothing  to see

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[DannyHamilton]

For Bitcoin to be sustainable indefinitely, it can't have a blockchain that keeps growing forever

Why not?

or a money supply that shrinks to nothing.
- snip -
it's reasonable to predict that the entire money supply will eventually be lost.

Actually, that isn't very likely to happen.

In order to preserve the money supply, there must be a way to recover lost or abandoned values and I can't see a way of doing this without putting expiration dates on UTXOs to make owners spend them at least once within a period of time to prove to the network that they aren't lost or abandoned.

You are welcome to go create your own altcoin if you want to be able to steal from people.  I ireally don't think you're going to be able to get a consensus on your idea.  Without consensus, it isn't going to happen.

[theymos]

This is a very old idea which has been discussed to death.

People joined Bitcoin knowing that bitcoins would gradually be lost over time. This is an important part of how the Bitcoin currency works. Therefore, reassigning "lost" BTC would be extremely similar to increasing the money supply beyond 21 million, and so it is an absolutely prohibited change. Nothing that does this can ever rightly be called Bitcoin, no matter how much consensus it has. If we ever run low on satoshi, the solution will be to increase precision, not to add more satoshi.

Expiring very old UTXOs but not reassigning their value is acceptable, though. In fact, this can be done in a softfork. I think that doing this would be a good idea:
- If apparently-lost BTC is at risk of being recovered illegitimately due to cryptographic weaknesses. The release of so many lost coins would be a major blow to the the economy. Once it looks like ECDSA will only be secure for 5 more years or so, I think that a timer should be started to expire all ECDSA-secured UTXOs at the expected point at which they will become too insecure.
- If storing the UTXO set becomes a very major bottleneck for full nodes and there are no other good alternatives to UTXO expiration on the table. Several years of advance warning should be given before the first expiration.

[Duomo]

^ Hi theymos  

I agree, there isn't a point of allocation of lost bitcoins. The expansion and making up for the lost private keys of specific stated 21 million seems contrary to the values of what bitcoin was define as from the beginning, a finite source.  Instead of increasing the supply, adaptations should be made in order to deal with the issues that come in the future. The likelihood that all bitcoins will be and not regularly available in the market is false. There will be limited supply that is shrinking, but to say at some at time in the future, the use of bitcoin due to supply and demand constraints makes it useless is the polar opposite to the situation occurring presently right now before our eyes.

[Dabs]

How big is too big? By the time the blockchain is 1 terabyte, we would all be using 16 TB solid state drives or larger, like the one Samsung showed off this year.

People heavily invested into bitcoin will be running a separate server just to host their own full node.

[achow101]

How big is too big? By the time the blockchain is 1 terabyte, we would all be using 16 TB solid state drives or larger, like the one Samsung showed off this year.

People heavily invested into bitcoin will be running a separate server just to host their own full node.

The Bitcoin network can currently handle 7 transactions per second. At 250 bytes per transaction on average, the blockchain is growing at 1.75KB/s- easy peasy. But if we want a network that can handle a million transactions per second, the blockchain will grow at 250MB/s, 15GB/m, 900GB/h, 21.6TB/d. That's way too much data for most PCs and way beyond the typical bandwidth of most cable ISPs.

We aren't going to handle a million transactions per second. Not even visa, one of the biggest payment processors, handles that much. They only handle around 3000 transactions per second, so we should target that.

[Dabs]

We're not going to hit as much as Visa or Mastercard or any of the other credit cards anytime soon, at least not the main blockchain. Remember, there will be off-chain transactions as well, like with those online wallets and bitgo and even side chains.

What will most likely happen is that more people will switch to light SPV clients, or mobile clients that work with servers, or some other solution that does not required the whole blockchain on your device.

If a business or enterprise wants their own full node, they will have their own server, or have it hosted. The blockchain is only 60 GB today. It will probably be double that by the end of 2016 (120 GB), and maybe double that by end of 2017 (240 GB). We'll have more space by then, faster, and I predict the death of mechanical platter spinning hard drives too (especially when SSD prices come close to HDD prices.)

Samsung already sells 2TB SSDs.

Most enterprise servers now or dedicated solutions have terabytes of space available in multiple 15k RPM drives running on some form of RAID for speed and redundancy.

When those enterprises switch to SSDs, they will sell their HDDs cheaply (or destroy them, but they can always have the drives wiped and still sold.)

I'm actually looking to buy some off-leased servers for myself, I mean, they come with 32GB to 64GB DDR3 RAM, dual quad core Xeon processors (16 threads with hyper threading), all for below $800. Stuff that cost $5000 about 5 years ago.

[larry_vw_1955]

Expiring very old UTXOs but not reassigning their value is acceptable, though.

Well you're half way there. you just need to realize that reassigning their value is perfectly fine and in line with satoshi's vision of having a fixed supply. no more and no less. the original poster deserves more credit than he got. that's for sure.

[DannyHamilton]

satoshi's vision of having a fixed supply. no more and no less.

(emphasis added by me)

I don't see why we should care at all what "Satoshi's Vision" was.  He's not a god, and he hasn't been involved in Bitcoin for over a decade now.

However, since you seem to care so much about what Satoshi would think...  You're wrong.

6. When someone loses his wallet, will there be a way to recreate the lost coins in the system ? Else the 21 million maximum will not be correct.

6:
Those coins can never be recovered, and the total circulation is less.  Since the effective circulation is reduced, all the remaining coins are worth slightly more.  It's the opposite of when a government prints money and the value of existing money goes down.

(emphasis added by me)

Clearly, Satoshi INTENDED for lost coins to remain lost, and was NOT in favor of reassigning that value.

[Dabs]

The question now is, define "very old", and at what threshold or age do "old coins" expire and are no longer redeemable or spendable?

Most fiat bank accounts of the world have some sort of 10 year time limit on "dormant" accounts, but 10 years might be too short. Some have even shorter time periods, 3 years, 2 years, 1 year. Perhaps there could be some sort of fork (soft or hard) where "very old" unspent UTXOs are expired after a certain future time, like 10 years from now, but only if they are still stuck in legacy addresses. I think any coins in newer segwit addresses (or future taproot addresses) should never expire as some people may be holding on to them for the next several decades.

It is good practice for wallets to move coins every year or two but that's besides the point.

[DannyHamilton]

10 years might be too short.

Much too short.  There are a variety of very good reasons someone might not touch their bitcoins for more than a decade.

Perhaps there could be some sort of fork (soft or hard) where "very old" unspent UTXOs are expired

Like, an altcoin?  Sure.  Go ahead and create a steal-a-coin cryptocurrency where you lose your coins after a while.  Let see how many people actually want to use it.

but only if they are still stuck in legacy addresses. I think any coins in newer segwit addresses (or future taproot addresses) should never expire as some people may be holding on to them for the next several decades.

Why should legacy addresses be treated any differently?

It is good practice for wallets to move coins every year or two but that's besides the point.

Every year or two?  Why would that be a good practice?  Sounds like a bad idea to me.

[Dabs]

Like, an altcoin?  Sure.  Go ahead and create a steal-a-coin cryptocurrency where you lose your coins after a while.  Let see how many people actually want to use it.

Not an altcoin. Not a steal-a-coin crypto. A can-not-spend-very-old-coin bitcoin for really very old addresses which are not double hash protected. No one is stealing the coins, just marking them as unspendable after they have not been spent 10 years from now (so, some really old coins not moved in 20 years). It was just a suggestion and I have no problem with no one doing anything about them as the coins are unlikely to be spent at all if no one has moved them in the past 10, 11, or 12 years.

This would of course, require consensus and that means everyone agrees to it.


The longest time frame I've seen for fiat banks is 15 years of inactivity, they then mark those as dormant and can "escheat" the money to the state or central bank or whatever. There are procedures for claiming that money. Imagine your great grandfather opened an account in your name when you were a child, put in a few thousand dollars, and you never knew about it until today, some 50 years later.

Why should legacy addresses be treated any differently?

There are some early addresses older than the most recent legacy addresses that were not protected behind a hash of a hash, so those coins can be stolen if enough computing power is put to them. The later legacy addresses are protected by a hash of a hash, so the public keys are unknown until they are spent, for those addresses which are re-used, which is not recommended these days.

I think the earliest addresses have their public keys known? Kindly correct me if I am mistaken. My own first addresses were those hash behind a hash types.

It is good practice for wallets to move coins every year or two but that's besides the point.

Every year or two?  Why would that be a good practice?  Sounds like a bad idea to me.

Yeah, so you know those coins are still spendable, and maybe to consolidate them as needed. Maybe you don't actually have to spend the coins, but just make sure you can restore from backup any cold storage you have, so you know you can spend them in the future. Of course, this is done either offline or with proper security practices.

I'm of the assumption that these coins are either in cold storage or protected behind a hardware wallet (which is = cold storage too.) If not, and you're still using hot wallets, then it would be wise to move any coins you don't need to spend immediately to cold storage.

Finally, if you suspect that someone may have access to your coins or your wallet could be compromised, you create a new wallet and move your coins there, then you know the new address is secure.

I do have some coins that have not moved in 8 years. They were paper wallets to begin with, I don't think they are moving on their own any time soon.

[BlackHatCoiner]

No one is stealing the coins, just marking them as unspendable after they have not been spent 10 years from now (so, some really old coins not moved in 20 years). It was just a suggestion and I have no problem with no one doing anything about them as the coins are unlikely to be spent at all if no one has moved them in the past 10, 11, or 12 years.

Actually, quite the opposite. Everyone's stealing the coins as they become slightly richer due to this feature. They become richer due to the user's inability to spend their funds.

The longest time frame I've seen for fiat banks is 15 years of inactivity, they then mark those as dormant and can "escheat" the money to the state or central bank or whatever. There are procedures for claiming that money.

I think that you should think of Bitcoin as cash; it has been told hundreds of times. What would happen if you left your cash or gold buried in the ground for over two decades? Would you be unable of spending them?

I think that you're trying to find a solution to a problem (Satoshi's rewarded addresses whose public key is exposed) and you introduce others by doing so. Of course, consensus is required to enable this. What I'm telling you is that the users will never come in an agreement for it due to its utopianism.

[n0nce]

I think that you're trying to find a solution to a problem (Satoshi's rewarded addresses whose public key is exposed) and you introduce others by doing so. Of course, consensus is required to enable this. What I'm telling you is that the users will never come in an agreement for it due to its utopianism.

I think stealing non-moved coins is really dumb and not needed, and nobody will agree to this idea.

However, I think it might be interesting to explore the idea of 'empty blocks' in the sense that if all utxos are spent, you don't have to keep them in the Blockchain.

But in general, all this topic is really 'trying to find an idea to a nonexistent problem'. Recently, someone brought to my attention how many people now have a 256GB phone. While the Blockchain is sitting at a bit over 300 gigs. The 'flippening' () is probably happening very soon where it will be normal to have enough space on your mobile phone to store the entire Bitcoin blockchain if you wanted. At that point, it will be an absolute no brainer to just run a full node on your multi-TB all-SSD PC or laptop at home.

As long as the Blockchain grows slower than storage for a given price (which it is) we don't have an issue to try to solve here.

Edit: I just realized this topic is 6 years old. I respect OP for thinking about blockchain size issues and potential solutions in a time where it wasn't yet clear that fast storage will be so cheap so soon. Prices fell from ~35ct/GB to ~8ct/GB. To get a 1TB SSD in 2015 cost ~350 bucks vs. 80 bucks now.

[BlackHatCoiner]

However, I think it might be interesting to explore the idea of 'empty blocks' in the sense that if all utxos are spent, you don't have to keep them in the Blockchain.

I've probably misunderstood what you said, but:  If you don't keep the spent transaction outputs, but rather dump them later instead, how will you maintain the chain? The PoW was done with these included.

[n0nce]

However, I think it might be interesting to explore the idea of 'empty blocks' in the sense that if all utxos are spent, you don't have to keep them in the Blockchain.

I've probably misunderstood what you said, but:  If you don't keep the spent transaction outputs, but rather dump them later instead, how will you maintain the chain? The PoW was done with these included.

No you're right, I didn't think this through at all so far, I don't think OP's idea would work without the 'deleting old utxos' part, I was just thinking maybe it could be possible but it's indeed not going to happen..

[larry_vw_1955]

I don't see why we should care at all what "Satoshi's Vision" was.

How can you say something like that? Of course we should care what his vision was. Now about that little quotations you provided. All I can about that is "my bad". 

[pooya87]

Not an altcoin.

It would be an altcoin.

There are some early addresses

They are using P2PK scripts where the output contains the public key instead of the hash of it and there is no "address" defined for these scripts, they are just outputs without a corresponding human readable string (aka an address).

so those coins can be stolen if enough computing power is put to them.

If by enough you mean a million+ years worth of computing power, then you are right.
Also your argument do not justify your idea simply because if ECC could be broken and bitcoin were still using it, then it would become obsolete as a whole.

[larry_vw_1955]

10 years might be too short.

Much too short.  There are a variety of very good reasons someone might not touch their bitcoins for more than a decade.

YOu are actually right. The correct timeframe could be more like 200 years.

I had been thinking about this issue and instead of creating a new thread, I decided to just add my proposal to the OP's since he and I have similar ideas. Hopefully satoshi if he is reading this would not only reward the OP but me as well.

Sweeping stale bitcoin utxos and putting them back into circulation

UTXOs older than a certain number of blocks are allowed to be mined by a miner and put into a block which will then delete the utxo and transfer a certain percentage of it's value to the miner that mined it. The other part will be distributed in a somewhat unpredictable/random fashion to some known active bitcoin addresses.

The UTXO set contains unspendable outputs. It also contains outputs that are theoretically spendable but can't be spent due to various reasons. Both of these problems could be resolved by adopting this practice of getting rid of stale utxos.

[Dabs]

Guys, I'm not talking about an altcoin, or if a fork is made and it turns out to be an altcoin that no one uses. We stick to bitcoin and if no one likes the idea, and no consensus is reached, then there are no changes. I don't agree with everything the OP said, except the part where unspent coins will remain unspendable.

Currently, they are unspent because they have not been spent, but can one day be spent. Whether ECC is broken or not, the concern is the public keys of those early addresses (P2PK) are known and exposed.

It also doubles as a Canary ... because then everyone will see that those coins get spent one day and we all suspect it's probably not Satoshi who moved them.

My idea was just building up on the OP, who said, if it's not been spent, let's make sure it never gets spent.

I have no issues leaving it the way it is, and this idea is not new, it has been brought up before by other people. We don't want reclaiming coins (and a lot do not want that), but I think unspent coins in P2PK addresses that have remained unspent for 20 years ought to become unspendable in the future.

By the way, does anyone have an idea how much BTC there are in P2PK addresses that have not moved since maybe 2011? (or when did we start not using P2PK addresses?). I read some estimates of about 2 million bitcoin in P2PK addresses that have not moved.

Relevant link: https://bitcoinist.com/bitcoin-worth-usd-40-billion-vulnerable-to-quantum-attacks/