Re: [Bitcoin-development] Proposal: Requiring a miner's signature in the block header

Re: [Bitcoin-development] Proposal: Requiring a miner's signature in the block header

[Ittay]

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A similar idea was proposed by Sirer and me as a part of two-phase proof of
work (2P-PoW) [1]. In 2P-PoW the first phase is Bitcoin's standard PoW and
the second phase requires the signature. This way Bitcoin doesn't lose its
mining power (read: security) in one day, but rather it is possible to
gradually switch from the current PoW to the signature-based one, slowly
phasing out the existing hardware and mining datacenters.

For a more general view of nonoutsourceable puzzles you can check out
Miller et al.'s paper [2].

Ittay

[1]
http://hackingdistributed.com/2014/06/18/how-to-disincentivize-large-bitcoin-mining-pools/

[2] https://cs.umd.edu/~amiller/nonoutsourceable.pdf

------------------------------
>
> Message: 2
> Date: Wed, 11 Feb 2015 08:54:15 +0000
> From: Hector Chu <hectorchu@gmail.com>
> Subject: [Bitcoin-development] Proposal: Requiring a miner's signature
>         in      the block header
> To: bitcoin-development@lists.sourceforge.net
> Message-ID:
>         <
> CAAO2FKEFxC_byt4xVJb0S-7yy0M7M-Av7MHUH-RBDuri_GAFtw@mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> A proposal for stemming the tide of mining centralisation -- Requiring a
> miner's signature in the block header (the whole of which is hashed), and
> paying out coinbase to the miner's public key.
>
> Please comment on whether this idea is feasible, has been thought of
> before,
> etc., etc. Thank you.
>
> Motivation
> ----------
>
> Mining is centralising to a handful of pool operators. This is bad for a
> number of political reasons, which we won't go into right now. But I have
> always believed that some years down the line, they could hold the users
> hostage and change the rules to suit themselves. For instance by
> eliminating
> the halving of the block reward.
>
> Solution
> --------
>
> Currently the block header is formed by the pool operator and distributed
> for
> hashing by the pooled miners. It is possible to divide the work among the
> miners as the only thing that is used to search the hash space is by
> changing
> a nonce or two.
>
> I propose that we require each miner to sign the block header prior to
> hashing. The signature will be included in the data that is hashed.
> Further,
> the coinbase for the block must only pay out to the public key counterpart
> of
> the private key used to sign the block header.
>
> A valid block will therefore have a signature in the block header that is
> verified by the public key being paid by the coinbase transaction.
>
> Ramifications
> -------------
>
> Work can no longer be divided among the pooled miners as before, without
> sharing the pool's private key amongst all of them. If the pool does try to
> take this route, then any of the miners may redeem the coinbase when it
> matures. Therefore, all miners will use their own key pair.
>
> This will make it difficult to form a cooperating pool of miners who may
> not
> trust each other, as the block rewards will be controlled by disparate
> parties
> and not by the pool operator. Only a tight clique of trusted miners would
> be
> able to form their own private pool in such an environment.
>
> Attacks
> -------
>
> Pooled hashpower, instead of earning bitcoins legitimately may try to break
> the system instead. They may try a double-spending attack, but in order to
> leverage the pool to its full potential the pool operator would again have
> to
> share their private key with the whole pool. Due to the increased
> cooperation
> and coordination required for an attack, the probability of a 51% attack is
> much reduced.
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> Message: 3
> Date: Wed, 11 Feb 2015 10:25:27 +0100
> From: Natanael <natanael.l@gmail.com>
> Subject: Re: [Bitcoin-development] Proposal: Requiring a miner's
>         signature in the block header
> To: Hector Chu <hectorchu@gmail.com>
> Cc: bitcoin-development@lists.sourceforge.net
> Message-ID:
>         <CAAt2M1_qj0r03=
> Ref9mN7bJLg-odep3m5teZ7JWDLC+zknQdQQ@mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Den 11 feb 2015 09:55 skrev "Hector Chu" <hectorchu@gmail.com>:
> >
> > A proposal for stemming the tide of mining centralisation -- Requiring a
> > miner's signature in the block header (the whole of which is hashed), and
> > paying out coinbase to the miner's public key.
> >
> > Please comment on whether this idea is feasible, has been thought of
> before,
> > etc., etc. Thank you.
> >
> > Motivation
> > ----------
> >
> > Mining is centralising to a handful of pool operators. This is bad for a
> > number of political reasons, which we won't go into right now. But I have
> > always believed that some years down the line, they could hold the users
> > hostage and change the rules to suit themselves. For instance by
> eliminating
> > the halving of the block reward.
>
> [...]
>
> > I propose that we require each miner to sign the block header prior to
> > hashing. The signature will be included in the data that is hashed.
> Further,
> > the coinbase for the block must only pay out to the public key
> counterpart of
> > the private key used to sign the block header.
>
> [...]
>
> > This will make it difficult to form a cooperating pool of miners who may
> not
> > trust each other, as the block rewards will be controlled by disparate
> parties
> > and not by the pool operator. Only a tight clique of trusted miners would
> be
> > able to form their own private pool in such an environment.
>
> People already trust things like cloud mining, so your solution with
> increasing technical trust requirements won't help. But you will however
> break P2Pool instead.
>
> Also, note that threshold signatures (group signatures) could probably be
> used by an actual distrusting pool's miners. There are already a proof of
> concept for this implemented with secp256k1 that works with Bitcoin clients
> silently. This wouldn't prevent such a pool from working.
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Re: [Bitcoin-development] Proposal: Requiring a miner's signature in the block header

[Mike Hearn]

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If you're interested in working on mining decentralisation, chipping away
at getblocktemplate support would be a better path forward. It's possible
to have decentralised pooled mining - I know it sounds like a contradiction
but it's not.

I wrote about some of the things that can be done in this blog post:

https://blog.bitcoinfoundation.org/mining-decentralisation-the-low-hanging-fruit/

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Re: [Bitcoin-development] Proposal: Requiring a miner's signature in the block header

[Natanael]

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Den 11 feb 2015 09:55 skrev "Hector Chu" <hectorchu@gmail.com>:
>
> A proposal for stemming the tide of mining centralisation -- Requiring a
> miner's signature in the block header (the whole of which is hashed), and
> paying out coinbase to the miner's public key.
>
> Please comment on whether this idea is feasible, has been thought of
before,
> etc., etc. Thank you.
>
> Motivation
> ----------
>
> Mining is centralising to a handful of pool operators. This is bad for a
> number of political reasons, which we won't go into right now. But I have
> always believed that some years down the line, they could hold the users
> hostage and change the rules to suit themselves. For instance by
eliminating
> the halving of the block reward.

[...]

> I propose that we require each miner to sign the block header prior to
> hashing. The signature will be included in the data that is hashed.
Further,
> the coinbase for the block must only pay out to the public key
counterpart of
> the private key used to sign the block header.

[...]

> This will make it difficult to form a cooperating pool of miners who may
not
> trust each other, as the block rewards will be controlled by disparate
parties
> and not by the pool operator. Only a tight clique of trusted miners would
be
> able to form their own private pool in such an environment.

People already trust things like cloud mining, so your solution with
increasing technical trust requirements won't help. But you will however
break P2Pool instead.

Also, note that threshold signatures (group signatures) could probably be
used by an actual distrusting pool's miners. There are already a proof of
concept for this implemented with secp256k1 that works with Bitcoin clients
silently. This wouldn't prevent such a pool from working.

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[Bitcoin-development] Proposal: Requiring a miner's signature in the block header

[Hector Chu]

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A proposal for stemming the tide of mining centralisation -- Requiring a
miner's signature in the block header (the whole of which is hashed), and
paying out coinbase to the miner's public key.

Please comment on whether this idea is feasible, has been thought of before,
etc., etc. Thank you.

Motivation
----------

Mining is centralising to a handful of pool operators. This is bad for a
number of political reasons, which we won't go into right now. But I have
always believed that some years down the line, they could hold the users
hostage and change the rules to suit themselves. For instance by eliminating
the halving of the block reward.

Solution
--------

Currently the block header is formed by the pool operator and distributed
for
hashing by the pooled miners. It is possible to divide the work among the
miners as the only thing that is used to search the hash space is by
changing
a nonce or two.

I propose that we require each miner to sign the block header prior to
hashing. The signature will be included in the data that is hashed. Further,
the coinbase for the block must only pay out to the public key counterpart
of
the private key used to sign the block header.

A valid block will therefore have a signature in the block header that is
verified by the public key being paid by the coinbase transaction.

Ramifications
-------------

Work can no longer be divided among the pooled miners as before, without
sharing the pool's private key amongst all of them. If the pool does try to
take this route, then any of the miners may redeem the coinbase when it
matures. Therefore, all miners will use their own key pair.

This will make it difficult to form a cooperating pool of miners who may not
trust each other, as the block rewards will be controlled by disparate
parties
and not by the pool operator. Only a tight clique of trusted miners would be
able to form their own private pool in such an environment.

Attacks
-------

Pooled hashpower, instead of earning bitcoins legitimately may try to break
the system instead. They may try a double-spending attack, but in order to
leverage the pool to its full potential the pool operator would again have
to
share their private key with the whole pool. Due to the increased
cooperation
and coordination required for an attack, the probability of a 51% attack is
much reduced.

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