Re: [bitcoin-dev] Year 2038 problem and year 2106 chain halting

[Kate Salazar <mercedes.catherine.salazar@gmail.com>]

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Hi yanmaani

On Sun, Oct 17, 2021 at 5:28 PM yanmaani--- via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> What, no. The `k` value is calculated implicitly, because there's only
> one value of it that could ever be valid - if `k` is 1 too small, we're
> 70 years too far back, and then the block will violate median of last
> 11. If `k` is 1 too large, we're 70 years too far in the future, then
> the block will violate 2 hour rule. Nothing is added to coinbase or
> anywhere else.
>
> It's possible that you'd need some extra logic for locktime, yes, but it
> would only be a problem in very special cases. Worst-case, you'll have
> to use block time locking in the years around the switch, or softfork in
> 64-bit locking.
>
> But unless I'm missing something, 32-bit would be enough, you just
> wouldn't be able to locktime something past the timestamp for the
> switch. After the switchover, everything would be back to normal.
>
> This is a hardfork, yes, but it's a hardfork that kicks in way into the
> future. And because it's a hardfork, you might as well do anything, as
> long as it doesn't change anything now.
>

"Anything" is quite a word.
Ideally, hard fork requires upgrading every node that can be upgraded,
or at least have the node operator's consent to lose the node (for every
node that can't be upgraded).


>
> On 2021-10-15 22:22, vjudeu@gazeta.pl wrote:
> > Your solution seems to solve the problem of chain halting, but there
> > are more issues. For example: if you have some time modulo 2^32, then
> > you no longer know if timestamp zero is related to 1970 or 2106 or
> > some higher year. Your "k" value representing in fact the most
> > significant 32 bits of 64-bit timestamp has to be stored in all cases
> > where time is used. If there is no "k", then zero should be used for
> > backward compatibility. Skipping "k" could cause problems related to
> > OP_CHECKLOCKTIMEVERIFY or nLockTime, because if some transaction was
> > timestamped to 0xbadc0ded, then that transaction will be valid in
> > 0x00000000badc0ded, invalid in 0x0000000100000000, and valid again in
> > 0x00000001badc0ded, the same for timelocked outputs.
> >
> > So, I think your "k" value should be added to the coinbase
> > transaction, then you can combine two 32-bit values, the lower bits
> > from the block header and the higher bits from the coinbase
> > transaction. Also, adding your "k" value transaction nLockTime field
> > is needed (maybe in a similar way as transaction witness was added in
> > Segwit), because in other case after reaching 0x0000000100000000 all
> > off-chain transactions with timelocks around 0x00000000ffffffff will
> > be additionally timelocked for the next N years. The same is needed
> > for each OP_CHECKLOCKTIMEVERIFY, maybe pushing high 32 bits before the
> > currently used value will solve that (and assuming zero if there is
> > only some 32-bit value).
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