[Bitcoin-development] BIP: Voluntary deposit bonds

[Sergio Lerner <sergiolerner@certimix.com>]

I propose to allow miners to voluntarily lock funds by letting miners
add additional inputs to the coinbase transaction. Currently the
coinbase transaction does not allow any real input  to be added (only a
pseudo-input).
This is a hard-fork, and we could include it the next time a hardfork is
made.
The modifications to the code are minimal (no more than 12 lines
modified where IsCoinBase() is called), and they generally involve
removing code, not adding.

Why ?

Because sometime in the future (maybe 5-10 years) we may have to deal
with problems of securing the blockchain, as the subsidy is lowered. We
don't want the number of confirmation blocks to be increased in
compensation because Bitcoin won't be able to compete with other payment
networks.
Then by having this hardfork now, we will be able to soft-fork later to
any rule we may came come up with involving deposit bonds,
proof-of-stake, and the penalization of double-mining (mining two blocks
at the same height) to prevent short-range attacks.

Can it hurt?

No. I doesn't not change the incentives or the security in any way, as
adding additional inputs to the coinbase transaction would be voluntary
until the time for a soft-fork comes.
We shouldn't hard-fork for this change only, but maybe we could do this
change when the next hard-fork is scheduled (when we increase the block
size?).

Regards, S.