Topic: Strange Timestamp Argument - page 2. (Read 312 times)

It doesn't. We consider the median timestamp of the last 11 blocks, and not all of the miners.

There is also the point about network adjusted time, which prevents the timestamp from drifting uncontrollably; nodes wouldn't accept your block if your timestamp deviates too far from the network adjusted time. Even if there were two miners, it doesn't mean that they can set their timestamp arbitrarily. The blockchain doesn't necessarily provides for an indisputable or concrete "timestamp" but rather it provides an environment where you are required to expend far more to re organize the blocks.

If I remember correctly, the time stamp of a block comes from the average of all of the miners.
If there were only two miners, they could use any forward time stamp that they'd want.
And as gmaxwell said, assuming the average of the miners is correct, the block numbers becomes a near indisputable time stamp for
the transactions that come on chain.. with enough miners and within a small error.

Block chain is one of the few things that can give a near indisputable time stamp.

I see, thank you for that insight. But you haven't denied whether these "erroneous" timestamps are possible. So let me ask you directly:

Is it possible for miners to include erroneous timestamps, regardless of how important they are?

If yes, can these timestamps have a negative effect on the inflation schedule or locktimes?

What do you mean by erroneous?

The protocol requires that timestamps be greater than the median of the last 11 blocks and less then 2 hours into the future from your own perspective.  If you get a block more than 2 hours in the future you won't accept it until its within 2 hours.  Any timestamp that passes these criteria is valid, anything else will be ignored.

Time based locktimes aren't based on the time on the current block anymore, but instead are based on the median of the last 11 blocks (the lowest timestamp the block could have).

The allowed 2 hour difference on the blocks timestamp allows a one time 2hr/2week = 0.5% difference in inflation, -- utterly irrelevant and well below the noise.

If yes, can these timestamps have a negative effect on the inflation schedule or locktimes?

Bitcoin's requirement for accurate time is *extremely* loose.  A sundial and an almanac is pretty much sufficient.


It's likely that the person you're quoting is confusing multiple different uses of the word 'clock'.

Bitcoin only has a timestamp in it at all to keep the inflation schedule on track and make the infrequently used time-relative locktimes work.  If we didn't care about those features it could just exclude the timestamp entirely-- and it would still be a clock, one that just ticks in the form of blocks.

People talk as if blockchains can function as trustless clocks, but this is simply not the case.

The idea of Bitcoin is that anyone who has knowledge of the protocol can log on and determine the correct state of the ledger trustlessly. I ask my peers for the current blockchain and choose the one that is both valid and has the most work.

However, this ideal is not entirely achieved. A block is only valid if its timestamp is close enough to the actual time. This means that malicious miners can confirm blocks with erroneous timestamps, and there would be no way for someone logging on for the first time to detect that this has happened. This is in stark contrast to the case of malicious miners confirming blocks with erroneous transactions, for these erroneous transactions can be detected using only the information internal to the blockchain.

Malicious miners can validate a block with an erroneous timestamp. If they are in the majority, their chain will have the most work. Anyone logging onto the network for the first time will not be able to detect that the time stamps are erroneous. There may be nodes running with no downtime who claim that the time stamps are indeed erroneous, but there is no way to confirm who is telling the truth.

The implication is precisely that the timestamps may have been forged and there is no way to detect this trustlessly. People talk as if blockchains can function as trustless clocks, but this is simply not the case.